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Volume 5 Issue 1

Issue of e-Polymers

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Journal Overview

Publicly Available August 31, 2013

Wear of thermoplastics determined by multiple scratching

M. Dolores Bermúdez, Witold Brostow, Francisco J. Carrión-Vilches, Juan J. Cervantes, Dorota Pietkiewicz

Article number: 001

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Abstract

We studied wear resistance in sliding by multiple scratching along the same groove for a variety of thermoplastics: polystyrene, styrene-acrylonitrile, polyamide 6 and polysulfone. Constant-load experiments were carried out with a micro scratch tester for several loads between 2.5 and 15 N; each time 15 scratches were performed. Except for polystyrene, all materials show an asymptotic residual depth as a function of the number of scratch tests performed. In contrast to other materials, polystyrene exhibits brittleness and debris formation. Scanning electron microscopy and scanning probe microscopy were used to characterize the deformation and wear mechanisms and were connected to the wear data obtained by multiple scratching. At 15 N we found a viscoelastic recovery for polystyrene of 27.8% while for polyamide 6 the corresponding value is 80.2%.

Publicly Available August 31, 2013

Poling of β-poly(vinylidene fluoride): dielectric and IR spectroscopy studies

Victor Sencadas, Carlos M. Costa, Victor Moreira, Jorge Monteiro, Sushil K. Mendiratta, João F. Mano, Senentxu Lanceros-Méndez

Article number: 002

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Abstract

β-Poly(vinylidene fluoride) (β-PVDF) exhibits ferroelectric properties due to the special arrangement of the chain units in the crystalline phase. The piezoelectric properties of the material can be optimised by poling the original stretched film. The main effect of the poling process is the alignment of the randomly organised dipolar moments against the applied field. In this work, poled and non-poled β- PVDF from the same batch are characterised by dielectric spectroscopy. The origin of the electrical and mechanical response of poled and non-poled β-PVDF were further explored by far IR spectroscopy and discussed on a molecular level. The main effect of the poling process on the dielectric response of the material is a small increase of the dielectric constant due to the preferential alignment of the main dipolar contribution and a slight decrease of the dielectric loss, due to the more organized amorphous structure. The conductivity is strongly increased by poling, especially the high-temperature conductivity, ascribed mainly to hopping conductivity due to free charges induced during poling. FTIR experiments indicate that the origin of these effects and also of the variations in the thermo-mechanical response of the material can be found in the reorientation of the crystalline dipoles along the poling field, together with a partial reduction of the amount of α phase and an increase of the amount of β phase. The α to β transformation, mainly due to the stretching process, seems to be optimized by the poling process.

Publicly Available August 31, 2013

Scratch velocity and wear resistance

M. Dolores Bermúdez, Witold Brostow, Francisco J. Carrión-Vilches, Juan J. Cervantes, Gowrisankar Damarla, Jose M. Perez

Article number: 003

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Abstract

Using a micro-scratch tester we have determined the influence of scratch velocity on the sliding wear resistance of several thermoplastics: polystyrene (PS), styrene-acrylonitrile, polyamide 6, polyethersulfone and polysulfone. Variable velocities (from 1 to 15 mm/min) were applied under two different load configurations: progressively increasing loads from 0.03 to 30 N and multiple scratching under constant loads from 2.5 to 10 N. Penetration and residual depth were measured along a 5 mm length. In the case of PS the scanning electron microscopy images of the progressive load scratch reveal a transition from shear yielding to crazing at low velocity. In multiple scratching tests the residual depths obtained at 1 mm/min are substantially higher than those at 15 mm/min for all thermoplastics tested. This result is explained by contact heating at higher speeds resulting in increased chain relaxation capability and thus more viscoelastic recovery. Scanning probe microscopy was used in order to observe surface damages. Except for PS, all other materials at all velocities exhibit asymptotic behaviour of the residual depth as a function of the number of tests.

Publicly Available August 31, 2013

Microwave dielectric properties of glass-reinforced polymers

Luís Cadillon Costa, Susana Devesa, Paulo André

Article number: 004

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Abstract

The well-balanced combination of properties of some polymers makes them good materials for industrial microwave applications, such as telecommunications or microwave ovens. Particular electrical properties are usually needed and can be controlled by additives. In this work, we present the results of complex dielectric permittivity measurements, ε* = ε’ - iε’’, in the microwave frequency region (2.7 and 12.8 GHz), at constant temperature 300 K, on different glass-reinforced and pigmented plastics (poly(butylene terephthalate), polypropylene and acrylonitrile- butadiene-styrene), using the resonant cavity method. We measured the shift in the resonant frequency of the cavity, Δ f , caused by the insertion of the sample, which can be related to the real part of complex permittivity, ε’, while the change in the inverse of the quality factor of the cavity, Δ(1/ Q ), gives the imaginary part, ε’’.

Publicly Available August 31, 2013

Rheological characterization of polymer-based nanocomposites with different nanoscale dispersions

Dong Gi Seong, Tae Jin Kang, Jae Ryoun Youn

Article number: 005

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Abstract

Polyamide 6 - clay nanocomposites with different nanoscale dispersions were prepared by melt compounding via twin-screw extrusion and their internal structures were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The rheological behaviour of these nanocomposites in shear and extensional flow were investigated using an Advanced Rheometric Expansion System and an Elongational Melts Rheometer in connection with the analysis by XRD and TEM. Nanocomposites with fully exfoliated structure and with poorly dispersed structure showed very different rheological behaviour. In general, addition of clay increased the viscosity and the storage modulus of nanocomposites, but different rheological behaviours were observed depending upon the degree of clay dispersion in the polymer matrix. In shear flow, only the exfoliated nanocomposite showed solid-like plateau behaviour in storage modulus and strong shear-thinning behaviour in shear viscosity. In extensional flow, only fully exfoliated nanocomposites showed strain-hardening behaviour, which is caused by the interaction between nanoparticles as well as between polymer molecules and nanoparticles.

Publicly Available August 31, 2013

Influence of adding poly(vinyl alcohol) fibres to poly(methyl methacrylate) matrix on the fracture behaviour of fibrereinforced composites

Vladimir Pavelka, Josef Jancar, Eva Nezbedova

Article number: 006

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Abstract

This paper reports on the relationship between structure and mechanical properties of poly(methyl methacrylate) (PMMA) reinforced with randomly oriented short poly(vinyl alcohol) (PVA) fibres. Special focus was on the effect of fibre content on the impact resistance of PMMA/PVA composites. Instrumented Charpy impact tests were carried out to characterize the impact resistance of PMMA/PVA composites. Linear elastics fracture mechanics was used to determine the dynamic critical strain energy release rate ( G Id ) and the critical stress intensity factor ( K Id ). Fracture surfaces were observed using scanning electron microscopy (SEM). Dynamic mechanical analysis was carried out to describe the viscoelastic response of the material. Finally, the behaviour of PMMA/PVA composites was interpreted using current short-fibre composite models. It was shown that a small amount of added PVA fibres (0.42 - 1.68 vol.-%) led to an increase of elastic modulus and yield stress under impact conditions. G Id was also slightly increased, but K Id remained unchanged. Good agreement was found between SEM observations and fracture toughness measured under impact loading.

Publicly Available August 31, 2013

Calorimetric investigation of the phase behaviour of the binary system 7-mPEG 5000-succinyloxymethyloxycarbonyl- Paclitaxel (PP7)/water

Jung-Sun Sohn, Soo-Kyung Choi, Byung-Wook Jo, Kirsten Schwark, Michael Hess

Article number: 007

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Abstract

Paclitaxel is an antineoplastic agent derived from the bark of the Pacific Yew Tree ( Taxus brevifolia ). Oral administration of the pure drug is problematic as it has a poor absorption due to its poor solubility in aqueous media. A specific water-soluble prodrug - PP7 - has been introduced by coupling the drug with a water-soluble polymer. For any kind of medical application and administration, knowledge of the binary isobaric phase-diagram is important since it gives information about solubility, phase transitions and the corresponding compositions. The system PP7 + H 2 O was studied calorimetrically from -20°C and shows the typical behaviour of an eutectic system. The properties of the phase diagram are discussed in view of other solution properties of the system presented earlier.

Publicly Available August 31, 2013

Degradation of polymeric systems aimed at temporary therapeutic applications: Structure-related complications

Michel Vert

Article number: 008

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Abstract

The number of degradable or biodegradable polymers that are aimed or claimed as aimed at therapeutic purposes is rapidly increasing in literature. In most cases, contributions deal primarily with synthesis. However it is the matching of degradation characteristics to application requirements that is important. This contribution, based on personal experience, is aimed at discussing some of the structure-related complications that can be expected when a polymeric therapeutic device degrades in an aqueous medium or in an animal organism. It is shown that dramatic changes can be observed because of selective degradation of some parts leading to the formation of undesired degradation by-products or undesired changes of properties.

Publicly Available August 31, 2013

Curing behaviour of epoxy resins with a diamine bearing an azobenzene group

Ewa Schab-Balcerzak, Henryk Bednarski, Henryk Janeczek, Danuta Sęk

Article number: 009

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Abstract

N , N -Diglycidylaniline (DGA) has been cured with the new chromophore 2,4-diamino-4'-methylazobenzene (DMAB). The curing kinetics of this aminophenyl epoxy resin/DMAB system was studied in isothermal experiments by means of differential scanning calorimetry. Autocatalytic behaviour is seen in the first stage of the cure and can be described by a model proposed by Kamal. The later stage is practically diffusion-controlled (beyond the glass transition). The diffusion effect is introduced into Kamal’s equation. Parameters such as rate constants and activation energies are calculated. Good agreement between calculations and experimental data is found. The curing kinetics of bifunctional DGA is compared with that of trifunctional N , N -diglycidyl-4-glycidyloxyaniline (DGOA) with the same tetrafunctional curing agent DMAB. The rate constants for DGA + DMBA are slightly higher than those for the DGOA + DMAB system. The activation energy for the former ( E 1 = 64.1 kJ/mol, E 2 = 56.2 kJ/mol) is lower than for the latter system ( E 1 = 71.6 kJ/mol, E 2 = 70.5 kJ/mol). DGA needs to be cured at a lower temperature than DGOA. The relationships between glass transition temperature, T g , and rate of conversion and time of curing is discussed as well. DGA cured with DMAB exhibits a lower T g (220°C) and thermal stability than DGOA + DMAB ( T g = 240°C) because of the lower functionality of the DGA resin. Preliminary investigations of optical grating recording in the new material were carried out. The presence of azobenzene groups in such epoxy systems enables their application as potential materials for holography.

Publicly Available August 31, 2013

Characterisation of ‘wet’ polymer surfaces for tissue engineering applications: Are flat surfaces a suitable model for complex structures?

Laleh Safinia, Jonny J. Blaker, Véronique Maquet, Aldo R. Boccaccini, Athanassios Mantalaris, Alexander Bismarck

Article number: 010

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Abstract

Tissue engineering scaffolds are 3D constructs that simulate the growth environment in vivo . The present work aims to address the question of whether thin films, i.e., flat surfaces, are a suitable model for more complex 3D structures? With this in mind a complete study of the morphology and surface chemistry of poly(D,Llactide) (PDLLA) substrates, fabricated into two different structures, is presented. The polymer structures studied include a 3D, porous, foam-like scaffold prepared by the thermally induced phase separation (TIPS) method and flat polymer thin films made by solvent casting. Based on the maximum bubble point test, a new method to assess the wettability of wet pore wall surfaces inside highly porous 3D structures was developed and tested. The maximum pore diameter determined using the maximum bubble point test for the total wetting liquids was confirmed through image analysis of scanning electron micrographs. The method allows the determination of the contact angle between the wet pore wall and a contacting liquid. The captive bubble method was employed to characterise the wettability of flat polymer films in contact with water. Both structures were further characterised using zeta- (ζ-) potential measurements to assess the surface chemistry of the polymer. The results demonstrate that PDLLA contains acidic functional groups and is hydrophobic. In order to evaluate the sensitivity of the test methods, the polymer surfaces were modified by protein adsorption using fibronectin and collagen. ζ-Potential and wettability measurements show that proteins indeed adsorb on virgin PDLLA surfaces. Protein adsorption causes the wettability of the PDLLA for water to improve. Our results strongly indicate that flat surfaces are not a suitable model for surfaces in complex 3D structures such as highly porous tissue engineering scaffolds. Such scaffolds must be characterised as a 3D system.

Publicly Available August 31, 2013

Porous polymeric scaffolds for bone regeneration

Katarzyna Filipczak, Ireneusz Janik, Marek Kozicki, Piotr Ulanski, Janusz M. Rosiak, Leonardo A. Pajewski, Radoslaw Olkowski, Piotr Wozniak, Anna Chroscicka, Malgorzata Lewandowska-Szumiel

Article number: 011

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Abstract

Solvent casting/particulate leaching has been used to synthesize highly porous polymeric scaffolds of controlled pore size, based on poly(methyl methacrylate) (PMMA) and poly(ε-caprolactone) (PCL). Obtained structures have a total porosity of c. 60%, with good interconnections between the pores. Porous scaffolds prepared using the greatest size of NaCl particles have the best mechanical properties. Both PMMA- and PCL-based materials can be sterilized by ionizing radiation. In the case of PCL-based scaffolds, irradiation causes cross-linking of polymer chains, which leads to an improvement of the mechanical properties of the scaffold. The compressive elastic modulus for non-porous samples increases with irradiation dose from 1.5 MPa for 0 kGy to 1.9 MPa for 280 kGy. Preliminary in vitro studies indicate good biocompatibility of both materials.

Publicly Available August 31, 2013

In vivo wear of polyethylene glenoid components in total shoulder arthroplasty

Wojciech Swieszkowski, Mark Frankle, Harald E. N. Bersee, Krzysztof J. Kurzydlowski

Article number: 012

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Abstract

Loosening of the glenoid component after a total shoulder arthroplasty, leading to pain and the need for a revision operation, accounts for one third of all shoulder replacement complications. It has been shown that glenoid loosening could be a result of osteolysis of periprosthetic bone induced by polymeric wear debris. The aim of this study was to determine the amount and pattern of in vivo wear of polyethylene glenoid components by examining a set of so-called retrievals. Six glenoid components were retrieved and examined (5 all-polyethylene and 1 metal-backed). The average time of functioning of these components in human bodies was 10 years with the shortest time of 7 and longest 14 years. Four components were scanned using a laser scanner. The results of measurements have been used to generate geometrical models of the retrievals using CAD software. These models have been subsequently used to determine the maximum depth and volumetric wear rate for each component. All six retrievals were examined using scanning electron microscopy (SEM). The maximum volumetric wear rate and wear depth for the analyzed retrievals was 30 mm 3 /year and 0.2 mm/year, respectively. From SEM analysis of the retrievals it was found that at macroscopic level the worn surfaces consist of (a) polished and (b) scratched regions. Intensive wear areas and fine multidirectional scratches were dominant in all retrievals. Random scratches were also observed, most probably due to third body wear (cement particles). In two implants pitting areas and surface micro-cracks have been observed, which most likely result from subsurface fatigue.

Publicly Available August 31, 2013

Optical methods to study the behaviour of supported metallocene catalysts during olefin polymerisation

Yong-Jun Jang, Kirsten Bieber, Corinna Naundorf, Nikolay Nenov, Markus Klapper, Klaus Müllen, Daniela Ferrari, Stefan Knoke, Gerhard Fink

Article number: 013

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Abstract

It is demonstrated that modern optical methods allow for a very fast study of the behaviour of supported metallocene catalysts. By videomicroscopy several polymeric supports functionalised with cyclopentadiene units or poly(ethylene oxide) and poly(propylene oxide) chains and loaded with a metallocene were simultaneously studied. In this example it is shown that this method allows for a direct comparison of different catalysts under identical conditions in a single experiment. In addition by this experiment more detailed information on the behaviour of the supports can be obtained by studying the growth kinetics of single grains. As a second tool, laser scanning confocal fluorescence microscopy (LSCFM) was applied. Using dye-labelled supports LSCFM can be used as a very rapid tool to study the fragmentation of supports. This is demonstrated by 3D images showing the distribution of different support fragments in the polyethylene product particles.

Publicly Available August 31, 2013

Interfacial studies of carbon fibre / polycarbonate composites using dynamic mechanical analysis

Maria C. Paiva, João F. Mano

Article number: 014

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Abstract

Unidirectional composite material samples with ultrahigh modulus carbon fibres, treated and untreated by oxygen plasma, and a polycarbonate matrix were prepared and tested. Dynamic mechanical analysis (DMA) was used to study interfacial fibre/matrix interaction and the fragmentation test method was applied to determine interfacial shear strength. For the composite samples with treated carbon fibres, analyzed by DMA, a consistent shift of the loss modulus peak toward higher temperature was observed. The damping ratio was highly affected by residual stresses along the carbon fibre direction due to the large difference of thermal expansion coefficients of matrix and fibres. Critical fibre length and interfacial shear strength, obtained from the fragmentation test, showed substantial improvement for treated fibres as compared to the untreated ones. Plasma oxidation of the fibre surface improved considerably the fibre-matrix interaction. Care must be taken interpreting the DMA results, due to specific characteristics of the system studied.

Publicly Available August 31, 2013

Radical crosslinking during polyhydrosilylation between fluorinated and silicone molecules: a model study

Claire Longuet, Amédée Ratsimihety, Francine Guida-Pietrasanta, François Ganachaud, Bernard Boutevin

Article number: 015

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Abstract

The present study deals with an explanation for crosslinking reactions that occur during the polyhydrosilylation of telechelic Si-H silicones with divinylperfluoro molecules. For a better understanding of the chemical process, a model reaction was performed and characterized by a full battery of techniques, including the different nuclei NMR analyses. Even if hydrosilylation occurs, side methyl groups on the silicon atoms also react with tert -butoxy radicals. Abstraction of a hydrogen radical from the methyl side group of the silicone chains allows the vinyl fluorinated molecules to add on polydimethylsiloxane and to bridge chains together.

Publicly Available August 31, 2013

Unsteady bi-directional heat transfer with heat generation by crystallization in high-density polyethylene

Wadou Baré, Carmen Albano, José Papa, Luis León

Article number: 016

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Abstract

A method of coupling the heat transfer during the cooling process of a molten sample of high-density polyethylene (HDPE) and the heat released by crystallization is presented. From the simulated temperature profiles it is possible to obtain the thermal diffusivity, which is one of the physico-chemical properties characterizing heat transfer under non-stationary conditions. Using suitable initial and boundary conditions, it was possible to solve the heat equation analytically. The results obtained for HDPE, using the diffusivity α = 0.00197 cm 2 /s, show an increase in the temperature profile when the term due to crystallization is taken into account, compared to the temperature profiles without heat generation between 140 - 110°C. This temperature range, where crystallization of HDPE occurs, was determined using differential scanning calorimetry. A cylindrical conductivity cell was constructed with a thermocouple placed at varying positions. Comparing the simulated temperature profiles including heat generation by crystallization with the experimental data, we find that in the latter case the increase in the temperature profile was less significant; this is probably due to the assumptions made in the development of the kinetic equation.

Publicly Available August 31, 2013

Synthesis and characterization of highly branched polymethacrylates via self-condensing oxyanionic copolymerization

Zhifeng Jia, Wei Huang, Deyue Yan

Article number: 017

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Abstract

Highly branched polymethacrylates were successfully synthesized by the self-condensing vinyl copolymerization of 2-dimethylaminoethyl methacrylate (DMAEMA) and methacrylic inimer containing a vinyl group and an oxyanionic active site, which was formed via the in situ reaction of 2-hydroxyethyl methacrylate (HEMA) with potassium hydride. Depending on the comonomer ratio, γ = [DMAEMA] 0 /[HEMA] 0 , branched poly(DMAEMA)s with number-average molecular weights between 4800 and 22 000 and degree of branching between 0.09 and 0.38 were obtained, as evidenced by gel permeation chromatography and NMR analysis. Thermally reversible phase transitions were observed for the branched poly(DMAEMA)s produced at higher comonomer ratio (γ ≥ 5). Quaternization of the branched poly(DMAEMA)s with methyl iodide led to cationic polyelectrolytes with branched structure.

Publicly Available August 31, 2013

Use of mesoporous silica as a reinforcing agent in rubber compounds

Betty L. López, León Dario Pérez, Mónica Mesa, Ligia Sierra, Eric Devaux, Mauricio Camargo, Christine Campagne, Stéphane Giraud

Article number: 018

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Abstract

Mesoporous silica is used as filler for styrene-butadiene rubber (SBR); filler-polymer interactions are compared with those exhibited when Ultrasil silica (VN3) is used. A silane coupling agent is added to improve filler dispersion and its influence on the bound-rubber formation is also investigated. The bound-rubber content is higher for the mesoporous silica and increases further for the sample containing silane. The increase is explained by chemical interactions between filler and rubber and penetration of the rubber chains into the mesopores. This is confirmed by 13 C solid-state NMR, IR spectroscopy and differential scanning calorimetry. Dynamic mechanical thermal analysis shows higher storage modulus for the rubber filled with mesoporous silica.

Publicly Available August 31, 2013

Relationship between structural evolution and rheological measurements for polymer + organoclay nanocomposites

Hee Bong Kim, Yang Hoon Hyun, Sung Taek Lim, Hyoung Jin Choi, Myung S. Jhon

Article number: 019

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Abstract

Nanocomposites with synthetic biodegradable aliphatic polyesters (BAP) were synthesized by the solution intercalation method with addition of organically modified montmorillonite. The hybrid structural evolution, caused by nanoscopic interaction between matrix polymer and layered silicate, was analyzed using viscoelastic properties obtained from oscillatory rheological measurements. Changes of viscoelastic properties to more solid-like, especially in the terminal region, were explained by both formation of specific BAP chain mesostructures with organoclay incorporated and a rheological percolation threshold. This behaviour was analyzed via a modified Cole-Cole plot evaluating the structural changes with filler concentration as well as the frequency dependence of dynamic modulus, complex modulus, and phase angle. Furthermore, the stress relaxation behaviour successfully demonstrated structural changes and critical concentration of nanocomposites with a jump shift of the longest relaxation time towards longer time.

Publicly Available August 31, 2013

Fast HPLC analysis of poly(ethylene oxide)s for highthroughput experimentation

Harald Pasch, Adele Brüll, Karin Cabrera

Article number: 020

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Abstract

Liquid chromatography of polymers is traditionally a slow technique with analysis times of typically 30 min per sample. For the application of liquid chromatographic techniques in combinatorial materials research the analysis time per sample must be reduced considerably. For fast high performance liquid chromatography (HPLC) small columns and new stationary phases with improved separation efficiencies can be used. HPLC separations of poly(ethylene oxide)s with different end groups can be conducted in less than 4 min. Accordingly, with new column technology and optimized separation methods time savings of more than 90% can be achieved as compared to conventional technology.

Publicly Available August 31, 2013

Thermo-responsive polymers and hydrogels in tissue engineering

Dirk Schmaljohann

Article number: 021

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Abstract

Various aspects of synthetic polymers and hydrogels in tissue engineering are discussed. A series of graft copolymers based on either N -isopropylacrylamide or N , N -diethylacrylamide as polymer backbone, and on poly(ethylene glycol) as side chain were prepared and characterized. These polymers were then used for the preparation of surface-immobilized hydrogels. The thermo-responsive behaviour was studied on model substrates by ellipsometry. The use of thermoresponsive polymers for in vitro studies allows the control of surface properties and thus the stimulation of cell adhesion and detachment through temperature changes. The cellular response was investigated by cultivation of mouse fibroblasts on surface-immobilized, thermo-responsive hydrogels. It was demonstrated that mouse fibroblasts adhere and detach as a function of the temperature, which then could be related to the change in surface properties. The concept is finally extended to the preparation of patterned hydrogels, which were studied by imaging ellipsometry.

Publicly Available August 31, 2013

Effects of photo-oxidation on tensile deformation behaviour in low-density polyethylene

Eiichi Miyagawa, Koh-hei Nitta, Akira Tanaka

Article number: 022

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Abstract

Quenched low-density polyethylene (LDPE) films were photo-oxidized with a xenon arc lamp at 63°C for 12 days. The effects of photo-oxidation on the deformation behaviour of LDPE films were investigated by a rheo-optical method in which IR dichroism was examined under uniaxial extension. The orientations of the oxidized segments introduced by photo-irradiation as well as of LDPE crystals were measured simultaneously with tensile deformation. The crystalline parts dominate the deformation before yielding but the orientation of oxidized segments gradually increases after yielding and has a maximum just before the break point.

Publicly Available August 31, 2013

Wetting of bioactive glass surfaces by poly(α-hydroxyacid) melts: interaction between Bioglass® and biodegradable polymers

Jonny J. Blaker, Véronique Maquet, Aldo R. Boccaccini, Robert Jérôme, Alexander Bismarck

Article number: 023

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Abstract

The interfacial characteristics between bioactive glass (45S5 Bioglass ® ) surfaces and poly(α-hydroxyacid) melts have been assessed by direct wetting measurements. In particular, the wettability of Bioglass ® powder by poly(D,Llactide) (PDLLA) and poly(D,L-lactide -co- glycolide) (PLGA) was assessed by imbibition measurements. Additionally, the equilibrium contact angles of PDLLA and PLGA melts on a sintered Bioglass ® surface were measured. The surface energy of the bioactive glass and the polymers was determined from contact angles measured using various test liquids on PDLLA, PLGA and Bioglass® solid substrates. There are sufficient adhesive interactions between the polymers and Bioglass ® . A simple heat treatment of the bioactive glass in an inert gas atmosphere leads to an improved wetting behaviour, indicating increased adhesive interactions. Scanning electron micrographs of the polymer + Bioglass ® composites formed by polymer penetration into the powder bed show the formation of a ‘good quality’ interface.

Publicly Available August 31, 2013

Modification of polymers by ultrasound treatment in aqueous solution

Bozena Rokita, Renata Czechowska-Biskup, Piotr Ulanski, Janusz M. Rosiak

Article number: 024

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Abstract

Ultrasound treatment, as an alternative to chemical and radiation-based processes, is an interesting technique for the modification of average molecular weights of natural and synthetic polymers in aqueous solution. Degradation is the observed main effect for strongly hydrophilic compounds - poly(acrylic acid) and chitosan. It is demonstrated that this process is caused by OH radicals as well as mechanochemical effects. Studies on more hydrophobic polymers - poly(ethylene oxide) and poly(ethylene glycol)s - indicate that here cross-linking and degradation occur side-by-side. The net effect of these competing reactions depends on the length of the polymer chains.

Publicly Available August 31, 2013

Synthesis and characterization of poly(methyl methacrylate) obtained by ultrasonic irradiation

Cristina Parra, Gema González, Carmen Albano

Article number: 025

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Abstract

We have studied the influence of surfactant nature and concentration, and monomer concentration on the synthesis of poly(methyl methacrylate) (PMMA) using high-frequency ultrasound. Polymerization was carried out via free radicals from aqueous solutions with several concentrations of an anionic (sodium lauryl sulfate, SLS) or a cationic surfactant (cetyltrimethylammonium bromide, CTAB) and different concentrations of the insoluble monomer methyl methacrylate (MMA) as the dispersed phase. The polymer particles obtained were characterized by FTIR, differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). The IR spectra show the presence of the characteristic absorption bands for PMMA when SLS was used. When CTAB was employed, for all surfactant concentrations and high monomer concentration (14% v/v), PMMA was obtained. However, bands of the surfactant were present for lower monomer concentrations. The glass transition temperature measured by DSC was in the range 106 - 126°C characteristic of PMMA. Maximum conversion was obtained when the anionic surfactant was employed. SEM studies show the formation of sub-micrometric PMMA latex spheres with average particle size from 65 to 100 nm when the anionic surfactant was used and 65 nm - 0.3 μm for the cationic surfactant.

Publicly Available August 31, 2013

Potentials of solvation of macromolecules as a measure of intermolecular interactions under viscous flow conditions

Anatoliy Filimoshkin, Sergey Safronov, Marina Safronova, Eugene Chernov

Article number: 026

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Abstract

Viscous flow of polymer solutions is depicted as a combined totality of elementary acts of flow within the bounds of the thermodynamic Joule cycle. Intrinsic viscosity of polymer solutions is represented as an energetical function of intermolecular interactions rather than a measure of additional loss of energy due to the rotational and viscoelastic deformations of macromolecules in the flow. A new theoretical concept in the light of the thermodynamic cycle analogous to that of Joule is brought forward to describe the viscous flow of polymer solutions. The concept is represented as a sequence of elementary cyclic processes described by equations, which establish a relationship between solvation potentials ( E ) and thermodynamic parameters such as temperature and volume. Solvation potentials are identified with the value of maximal solvation work and allow evaluating the energy of the corresponding intermolecular interactions via E , individually of electrostatic ( E a ) and covalent ( E b1 , E b2 ) nature.

Publicly Available August 31, 2013

Magnetic colloids: preparation and biomedical applications

Abdelhamid Elaissari

Article number: 027

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Abstract

Increasing interest has been focused on the preparation of magnetic latex particles and their use in biomedical diagnostics. All elaborated magnetic colloidal particles or latexes are principally used as a solid support of biomolecules involved in the specific capture of targeted biomolecules such as antigens in immunoassays (i.e., ELISA) and nucleic acid detection in ELOSA. Nowadays, the main objective in biomedical diagnosis is to enhance the sensitivity and to accelerate the procedure by elaborating new magnetic colloidal particles and diagnostic methods. The general problem in this field is related to the limited sensitivity. One possibility to partially solve it is to increase the concentration of captured targets (antigens, nucleic acids, etc.) before the specific detection step. Thus, the use of appropriate magnetic colloidal particles and methods for extraction and concentration of biomolecules is of extreme interest.

Publicly Available August 31, 2013

Alginate hydrogel – candidate support for cell transplantation

Piotr Woźniak, Marek Kozicki, Janusz M. Rosiak, Jacek Przybylski, Malgorzata Lewandowska-Szumieł

Article number: 028

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Abstract

Human cartilage derived cells were encapsulated in alginate hydrogel beads. Viability of the cells was determined using both qualitative (microscopy) and quantitative (MTT and NR assays) examination. Microscopy indicated that encapsulated cells remained viable during the 7-days experiment. The quantitative tests failed to give reliable results. Possible factors affecting the results of the quantitative study are discussed.

Publicly Available August 31, 2013

Carbon composite material and polysulfone modified by nano-hydroxyapatite

Barbara Szaraniec, Patrycja Rosół, Jan Chłopek

Article number: 029

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Abstract

This paper reports on mechanical and biological properties of carboncarbon 1 composites and polysulfone modified by hydroxyapatite (HAP), both natural (nano-particles) and synthetic (micro-particles) minerals. Results show that carbon-HAP composites have mechanical properties similar to carbon-carbon composites, while addition of HAP to polysulfone causes advantageous growth of Young’s modulus and limitation of creep, and disadvantageous decrease of tensile strength. Tests performed in simulated body fluid for carbon-HAP and polysulfone- HAP composites prove that the process of hydroxyapatite build-up becomes most intensive in the case of composites with nano-particles originating from natural hydroxyapatite.

Publicly Available August 31, 2013

Sulfonated poly(arylene thioether ketone ketone sulfone)s for proton exchange membranes with high oxidative stability

Liping Shen, Guyu Xiao, Guoming Sun

Article number: 030

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Abstract

Sulfonated poly(arylene thioether ketone ketone sulfone)s (SPATKKS) were synthesized by nucleophilic polycondensation of various amounts of 1,3- bis(4-fluorobenzoyl)benzene, 1,3-bis(3-sodium sulfonate-4-fluorobenzoyl)benzene, and 4,4’-dichlorodiphenylsulfone with 4,4’-thiobisbenzenethiol. Sulfonated poly- (arylene ether ketone ketone sulfone)s were also prepared in order to compare their oxidation resistance to peroxides with that of SPATKKS. SPATKKS show high oxidation resistance to peroxides. The resulting ionomers with moderate ion exchange capacity present excellent thermal stability (the 5% weight loss temperature is about 500°C) and low water uptake and swelling ratio until 85°C. The materials hold promise for application as proton exchange membranes in fuel cells.

Publicly Available August 31, 2013

Simulation of the shrinkage of dental polymeric composites

Tomasz Boguszewski, Wojciech Swieszkowski, Malgorzata Lewandowska, Krzysztof J. Kurzydlowski

Article number: 031

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Abstract

The aim of this study was to investigate the influence of size and shape of ceramic filler in dental composites on polymerization shrinkage. Moreover, the influence of resin shrinkage itself on the whole composite shrinkage was investigated. In 3D linear elastic finite element analyses, the process of shrinkage of dental resin/ceramic composites during polymerization was simulated using the ANSYS software. Composites were modelled with volumetric content of ceramics ranging from 0 up to 45%. Aggregates with different shape and size were analysed. Quantitative estimates have been obtained of the reduction in composite shrinkage with increasing content of ceramic aggregate or decreasing shrinkage of the resin. It has been found that by adjusting aggregate size and resin shrinkage a lower shrinkage of the dental composite may be obtained.

Publicly Available August 31, 2013

Kinetic investigation of styrene emulsion polymerization with surface-active polyelectrolytes as emulsifier, 1 Kinetic study

Satoshi Kato, Kiyoshi Suzuki, Mamoru Nomura

Article number: 032

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Abstract

A copolymer of methyl methacrylate and methacrylic acid to be used as a polymeric surfactant was synthesized by emulsifier-free semi-batch emulsion copolymerization. Emulsion polymerization of styrene was carried out at 50°C utilizing the ammonium salt of the copolymer as the polymeric emulsifier and potassium persulfate as the initiator, respectively. Both the number of polymer particles produced and the rate of polymerization were proportional to the 0.6 power of the initial emulsifier concentration, to the 0.4 power of the initial initiator concentration, and independent of the initial monomer concentration, respectively. These relationships are almost the same as those observed in the emulsion polymerization of styrene conducted using conventional surfactants like sodium dodecyl sulfate as the emulsifier and potassium persulfate as the initiator.

Publicly Available August 31, 2013

Cyclodextrin in polymer chemistry: Kinetic studies on the free-radical polymerization of cyclodextrin-complexed styrene from homogeneous aqueous solution

Helmut Ritter, Christopher Steffens, Joachim Storsberg

Article number: 033

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Abstract

Styrene was encapsulated by an equimolar amount of randomly methylated β-cyclodextrin (CD) in water resulting in a water-soluble CD complex. Polymerization of this complex was carried out at 50°C using different amounts of the water-soluble azo-initiator 2,2’-azobis[ N , N ’-dimethyleneisobutyramidine] dihydrochloride. Unthreading of CD during polymerization led to water-insoluble polystyrene. Analysis of the polymers obtained showed that the polymerization from homogenous aqueous solution can be described by an equation similar to the classical polymerization in solution (number-average degree of polymerization vs. initiator concentration: P n -1 ~ [I] 0.5 ).

Publicly Available August 31, 2013

Atom transfer radical polymerization of styrene initiated by the novel initiator 2-bromo-2-nitropropane

Gang Wang, Xiulin Zhu, Cheng Zhengping, Jian Zhu

Article number: 034

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Abstract

Heterogeneous atom transfer radical polymerization (ATRP) of styrene initiated by 2-bromo-2-nitropropane in bulk was carried out with CuCl/2,2′-bipyridine as the catalyst. The kinetics was first order in monomer and the numberaverage molecular weight of the polymer increased linearly with monomer conversion, indicating the ‘living’/controlled nature of the polymerization. However, the number-average molecular weight was usually higher than the theoretical one. The nitro group might react with the Cu complex, resulting in insufficient initiation. The amount of catalyst has no effect on the controllability of this catalyst system for the ATRP of styrene. The presence of a halide end group in the obtained polymer was confirmed by both 1 H NMR and chain-extension reaction.

Publicly Available August 31, 2013

Synthesis, characterization and ring-closing depolymerization of furanic polyesters

Wided Kamoun, Slim Salhi, Souhir Abid, Martine Tessier, Rachid El Gharbi, Alain Fradet

Article number: 035

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Abstract

Furanic polyesters were prepared by the bulk polycondensation of 5,5'- isopropylidene-bis(2-furoic acid) with 1,2-ethanediol, 1,4-propanediol and 1,6- hexanediol, and were characterized by size exclusion chromatography, NMR and MALDI-TOF MS. The ring-closing depolymerization of these polyesters was then investigated at 10 g/L concentration in 1-methylnaphthalene at 130 - 240°C. Chain flexibility, the use of zinc diacetate catalyst and, particularly, the presence of hydroxy end-groups were found to be favourable factors for the formation of high yields of cyclic oligoesters. A side reaction leading to the formation of non-reactive furyl-terminated species took place when the reactions were carried out at high temperature (240°C), limiting the yield of cyclic oligoesters.

Publicly Available August 31, 2013

Novel, biocompatible polyether(meth)acrylate-based formulations for stereolithography – A new flexible material class for three-dimensional applications

Arthur Thomas Bens, Carsten Tille, Günter Bermes, Moritz Emons, Hermann Seitz

Article number: 036

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Abstract

Herein we present a novel polyether(meth)acrylate-based resin material for stereolithography and other photolithographic applications with outstanding flexible material characteristics. This group of photopolymeric resin products combines the advantages of a non-toxic (meth)acrylate-based process material with a broad spectrum of adjustable low Young’s modulus material characteristics. In contrast to the mostly rigid and non-flexible process materials used at the moment in the engineering world, these formulations are able to fulfil the extended need for a very flexible and also biocompatible engineering material, especially for threedimensional models or prototypes in the medical technology area. A short overview over the bandwidth of possible material characteristics is given in this publication.

Publicly Available August 31, 2013

Poly(vinyl alcohol) nanofibres by electrospinning: influence of molecular weight on fibre shape

Zeng Jun, Haoqing Hou, Joachim H. Wendorff, Andreas Greiner

Article number: 037

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Abstract

Poly(vinyl alcohol) (PVA) nanofibres were obtained by electrospinning of PVA/water solutions. Formation of beaded fibres combined with decreased fibre diameters was observed for low PVA concentrations. Electrospinning of blends of PVA of different molecular weight resulted in less bead formation and smaller fibre diameters as compared to corresponding homopolymers of similar viscosity.

Publicly Available August 31, 2013

Scanning electron microscopy investigation of tooth/filling bonding

Joanna Siejka-Kulczyk, Małgorzata Lewandowska, Marta Raczyńska, Elżbieta Jodkowska, Krzysztof J. Kurzydłowski

Article number: 038

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Abstract

Scanning electron microscopy (SEM) investigations have been conducted to determine the influence of selected material on tissue/material bonding. Extracted human teeth were used in this study. Several resin composites were tested as dental fillings. To reveal the structure of the tissue/filling interface, the teeth were cut parallel to the long axis. Bonding quality was determined by direct SEM observation and microanalysis with X-ray energy spectrometry (EDX). The investigated materials show good bonding with enamel.

Publicly Available August 31, 2013

Comparison of two algorithms for calculation of the apparent rate constant in the kinetic modelling of diallyl terephthalate bulk polymerization

Iztok Hace

Article number: 039

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Abstract

In the present study a comparison was made of two most frequently used algorithms for calculation of the apparent rate constant in the kinetic modelling of bulk cross-linking diallyl terephthalate (DAT) polymerization with four different peroxide initiators, bis(4 -tert- butylcyclohexyl) peroxydicarbonate, dicyclohexyl peroxydicarbonate, benzoyl peroxide and dicumyl peroxide, in the temperature range from 50 to 150°C and at three different initiator loadings. The first algorithm is the CCS algorithm developed by Chiu, Carratt and Soong and the second is the S algorithm developed by Smoluchowski. Only two kinetic parameters had to be found by fitting a previously proposed kinetic model for bulk DAT polymerization, developed by Hace et al. , to measured conversion points. Conversions and other necessary physico-chemical properties used for kinetic modelling were obtained from our previous kinetic studies on DAT polymerization.

Publicly Available August 31, 2013

A facile method to prepare methylcellulose from annual plants and wood using iodomethane

Daiyong Ye, Xavier Farriol

Article number: 040

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Abstract

A novel facile method was developed to prepare methylcellulose from miscanthus, cardoon and eucalyptus. Pulps were obtained by the impregnation rapid steam pulping process (IRSP). A total-chlorine-free (TCF) method was used to bleach the pulps with hydrogen peroxide. Bleached pulps were mercerized in 40% NaOH solution for one hour at ambient temperature. Mercerized cellulose reacted with iodomethane in 2-propanol slurry at 60°C for 22 h. Mercerization and methylation were repeated. Intrinsic viscosities of methylcellulose were measured in 4% NaOH solution. Super-molecular substitution patterns of methylcellulose were determined by 13 C NMR. Molecular weights of methylcellulose were measured in dimethyl sulfoxide by gel permeation chromatography. Pulping severity is a key factor influencing the properties of the methylcellulose prepared.

Publicly Available August 31, 2013

High-throughput screening of the chemical composition distribution of random styrene-butyl acrylate copolymers

Iván García Romero, Harald Pasch

Article number: 041

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Abstract

The development of high-throughput liquid chromatographic techniques for the analysis of styrene-butyl acrylate (SBA) copolymers is discussed. The analysis time in size-exclusion chromatography (SEC) can be reduced to about 3 min per sample when high-throughput SEC columns and high flow rates are used. In gradient HPLC, small columns with improved separation efficiencies can be applied. The time requirements can be decreased to less than 2 min per sample. Using the high-throughput HPLC technique, the chemical composition distribution of high-conversion SBA copolymers can be analyzed in a fast and efficient way. The calibration of HPLC separation is conducted by coupling the HPLC system with FTIR through the LC-transform interface. A comparison of the chemical compositions of the copolymers obtained by 1 H NMR, off-line FTIR and coupled HPLCFTIR verifies the accuracy of the high-throughput copolymer analysis approach.

Publicly Available August 31, 2013

SEC/MALDI-TOF Mass spectrometry study of hydroxy-, carboxy- and methyl ester-terminated aliphatic polyesters

Slim Salhi, Martine Tessier, Jean-Claude Blais, Rachid El Gharbi, Alain Fradet

Article number: 042

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Abstract

Poly(ethylene adipate) (PEA) and poly(ethylene dodecanedioate) (PED) with dicarboxy-, dihydroxy-, dimethyl ester- and hydroxy-carboxy end-groups were synthesized and characterized by 13 C NMR and MALDI-TOF MS. Size-exclusion chromatography (SEC) fractions of these polyesters were analyzed by MALDI-TOF MS and used as standards to obtain SEC calibration curves leading to the absolute molar masses of the unfractionated polyesters. PEA and PED calibration curves were different from each other, but the same calibration curve was obtained for each type of polyester, irrespective of the nature of end-groups, showing the predominant role of the nature of repeating units on the hydrodynamic volume of oligoesters. The study also shows that the conventional SEC calibration method using polystyrene standards leads to a significant overestimation of polyester average molar masses.

Publicly Available August 31, 2013

Self-ignition of polymerization fronts with convection: the ‘rainstorm effect’

Simone Bidali, Arnaud Ducrot, Alberto Mariani, Mauro Rustici

Article number: 043

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Abstract

This work is devoted to an experimental and numerical study on the influence of natural convection on the ignition of polymerization reaction fronts. Numerical simulations confirm experimental findings. Indeed, it has been observed that under the same initial and boundary conditions the front ignition can occur either in the centre of the reactor or at the top. The difference between these two cases is determined by the viscosity of the medium and by other parameters that can influence the convective motion of a liquid monomer. If the viscosity is low, weak convective motion in the beginning of the development of the reaction will lead to the accumulation of the hotter monomer at the top of the reactor. In this case, front ignition occurs at the top and propagates downwards ( rainstorm effect ). If the viscosity is sufficiently high, the convective motion does not essentially change the position of the emerging hot spot; the front appears at the centre of the reactor and propagates almost spherically outwards.

Publicly Available August 31, 2013

Separation of linear and star-shaped polystyrenes by two-dimensional chromatography

Johannes Gerber, Wolfgang Radke

Article number: 044

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Abstract

Investigation of star-shaped polystyrenes using gradient chromatography shows a retention that only depends on the total molecular weight and not on the number or molecular weight of the arms. In contrast, size-exclusion chromatography (SEC) separates according to hydrodynamic volume. For a mixture of a star polymers having an arm molecular weight of 4800 and a linear polystyrene a direct 2-dimensional separation using gradient chromatography as a first dimension and SEC as a second dimension resulted in a clear separation of the different topologies. Star polymers of higher arm molecular weight could not be separated from their linear analogues by direct coupling of gradient chromatography and SEC.

Publicly Available August 31, 2013

‘Surfactant-free’ stable nanoparticles from biodegradable and amphiphilic poly(ε-caprolactone)-grafted dextran copolymers

Isabelle Ydens, Philippe Degée, Cécile Nouvel, Edith Dellacherie, Jean-Luc Six, Philippe Dubois

Article number: 045

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Abstract

A variety of poly(ε-caprolactone)-grafted dextran copolymers were synthesized with a controlled architecture through a three-step procedure: partial protection of the dextran hydroxyl groups by silylation, ring-opening polymerization of ε-caprolactone initiated from remaining free hydroxyl groups on partially silylated dextran, and silyl ether deprotection under mild conditions. The potential of these amphiphilic grafted copolymers as surfactants was investigated by water/toluene interfacial tension measurements. Since each copolymer showed noticeable surfactant properties, their ability to form ‘surfactant-free’ nanoparticles was evaluated using the nanoprecipitation method. It was found that remarkably stable core (polyester) - shell (polysaccharide) nanoparticles with a mean diameter around 200 nm were formed.

Publicly Available August 31, 2013

The effect of curing on sorption and diffusion of a brake fluid in EPDM elastomer

Tahereh Darestani Farahani, Gholam Reza Bakhshandeh

Article number: 046

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Abstract

The effect of a poly(ether glycol) brake fluid on cured EPDM (ethylenepropylene- diene monomer) elastomer based on 5-ethylidene-2-norborene has been studied. Different amounts of dicumyl peroxide (DCP) curing agent were used and the effect of ageing in a brake fluid (at 100°C for 70 h) on technical properties of EPDM have been investigated. By increasing the amount of DCP, significant changes were not observed. Tensile strength and modulus increased but elongation at break and abrasion loss decreased due to oxidative degradation and crosslinking. Hardness was constant due to the replacement of plasticizer with brake oil.

Publicly Available August 31, 2013

New supramolecular crystalline polymer structure of syndiotactic polystyrene

Mark van Heeringen, Bob Vastenhout, Rudy Koopmans, Ludo Aerts

Article number: 047

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Abstract

Semi-crystalline polymers such as polyethylene and isotactic polypropylene are known to yield lamellar meso-structures through macromolecular chain folding upon solidification from the molten state. The lamellae typically assemble to form microscopic spherulitic or ‘shish-kebab’ super structures depending on the cooling condition being either quiescent or induced during flow. Cooling experiments with concentrated solutions of syndiotactic polystyrene, however, unexpectedly yielded a novel microscopic superstructure resembling a ‘bird nest’. These super structures can be made reproducibly under specific conditions. They reflect the impact of a chiral centre on the molecular organisation on the meso and micro level during a solidification process.

Publicly Available August 31, 2013

A new approach to multiblock copolymers using atom transfer radical coupling

René Nagelsdiek, Helmut Keul, Hartwig Höcker

Article number: 048

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Abstract

Atom transfer radical coupling (ATRC) is a method for chain extension of styrene homopolymers prepared by atom transfer radical polymerization (ATRP). This concept is used to produce multiblock copolymers from block copolymers prepared via ATRP of styrene using various macroinitiators. ATRC comprises the reactivation of the dormant species at the chain ends. In the absence of monomer, the active radical species recombine to give chain extension (from polystyrene, PS) or multiblock copolymers (from block copolymers). The application of ATRC to PS block- poly(bisphenol A carbonate) -block- PS (PS -b- PC -b- PS) was not successful because chain degradation of the PC block occurs. However, poly(phenylene oxide) -block- PS (PPO -b- PS) and PS -b- PPO -b- PS were successfully transformed into tri- and multiblock copolymers by ATRC, although the coupling efficiency is not as high as observed for PS oligomers under similar conditions.

Publicly Available August 31, 2013

Enhancement of sensitivity and selectivity in surface plasmon resonance detection of a DNA point mutation by polymeric microspheres

Haruma Kawaguchi, Yasunobu Sato, Aya Okumura, Motoki Kyo

Article number: 049

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Abstract

Polymeric microspheres were used to enhance sensitivity and selectivity in the detection of DNA point mutations with a surface plasmon resonance (SPR) biosensor. First, single-strand DNA probes were immobilized onto epoxy group derivatized gold surfaces and the hybridization of DNA targets was monitored. SPR response was small. The subsequent interaction with DNA-carrying microspheres enhanced the response due to a significant increase of mass bound to the targets. After this, the flow rate of the buffer solution was increased during dissociation. An increase in shear stress resulted in the detachment of DNA-carrying microspheres hybridized with mismatched pairs and so the increasing ability to discriminate the point mutation. The same effect was reached by an increasing viscosity of the buffer solution.

Publicly Available August 31, 2013

Synthesis of fructooligosaccharide-based plastic films starting from inulin

Gerlinde Grandtner, Nicolas Joly, Jean-Paul Cavrot, Robert Granet, Geza Bandur, Lucian Rusnac, Patrick Martin, Pierre Krausz

Article number: 050

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Abstract

In this preliminary study, inulin, a fructooligosaccharide extracted from chicory roots, was converted into plastic films by acylation in homogeneous medium and under conventional heating, using methacryloyl and lauroyl chlorides as acylating reagents and N , N -dimethyl-4-aminopyridine as basic catalyst. Products were analyzed by FT-IR and 1 H NMR spectroscopies to confirm their structures. A preliminary study of their thermal properties was also achieved.

Publicly Available August 31, 2013

Silica-coating of fluorescent polystyrene microspheres by a modified Stöber method and their stability against photobleaching

Yoshio Kobayashi, Kiyoto Misawa, Masaki Kobayashi, Motohiro Takeda, Mikio Konno, Masanobu Satake, Yoshiyuki Kawazoe, Noriaki Ohuchi, Atsuo Kasuya

Article number: 051

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Abstract

Submicron-sized polystyrene spheres incorporating fluorescence dyes (fluorescent microspheres) were coated with silica by means of a seeded polymerization technique based on the Stöber method. Silica-coating of the fluorescent microspheres with a size of 100 nm was performed in the presence of 0 - 10 g/l polyvinylpyrrolidone (PVP), 1 - 13 mol/l water, 0 - 0.8 mol/l aq. ammonia and 0.00038 - 0.2 mol/l tetraethoxyorthosilicate (TEOS). The addition of PVP was found to suppress the generation of free silica particles and produced no shell-free fluorescent microspheres improving the uniformity of shell thickness of silicacoated fluorescent microspheres. Silica shell thickness increased from 11 to 63 nm with increasing TEOS concentration at 10 g/l PVP, 0.4 mol/l aq. ammonia and 11 mol/l water. Silica-coated fluorescent microspheres showed more stable fluorescence to laser-irradiation than uncoated fluorescent microspheres.

Publicly Available August 31, 2013

Three-dimensional numerical simulation of viscoelastic flow through an abrupt contraction geometry

Young Il Kwon, Dongjin Seo, Jae Ryoun Youn

Article number: 052

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Abstract

A numerical scheme for simulating three-dimensional viscoelastic flow was developed. The three-dimensional finite volume method (FVM) based on a non-staggered grid and the semi-implicit method for pressure-linked equations (SIMPLE) were adopted to solve the continuity and momentum equations. As we used a non-staggered grid, the momentum interpolation method (MIM) was employed to avoid checkerboard type pressure fields. Viscoelastic properties of the fluid were described by the Phan-Thien and Tanner (PTT) model, which was treated by the compressive interface capturing scheme for arbitrary meshes (CICSAM). The elastic viscous split stress scheme (EVSS) was used to decouple the velocity and the stress fields. Algebraic equations obtained by the above schemes were handled by an iterative solver and a multi-grid method was applied to accelerate convergence. In order to verify the scheme developed in this study, Newtonian flow in a rectangular duct was studied and the resulting velocity fields were compared with the analytical flow fields. Then viscoelastic flow in 4:1 contraction geometry, one of the most frequently used benchmarking problems, was predicted by applying the fully three-dimensional finite volume method.

Publicly Available August 31, 2013

Development of high-temperature separation techniques for the chemical composition analysis of ethylene - methyl methacrylate block copolymers

Lars-Christian Heinz, Sven Graef, Tibor Macko, Robert Brüll, Sven Balk, Helmut Keul, Harald Pasch

Article number: 053

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Abstract

Ethylene - methyl methacrylate block copolymers are semicrystalline polymers that dissolve in organic solvents only at high temperatures. Accordingly, microstructure analysis by solution methods must be conducted at temperatures above 130°C. For the analysis of block copolymers of different compositions several analytical techniques were used, including high-temperature size-exclusion chromatography (SEC), hyphenated SEC-FTIR, and CRYSTAF (crystallisation analysis fractionation). While SEC with refractive index detection indicated a certain multimodality of the samples, SEC coupled with FTIR revealed that the samples were chemically inhomogeneous and may contain homo- and copolymer fractions. The presence of polyethylene and poly(methyl methacrylate) homopolymers in the copolymer samples was confirmed by CRYSTAF analysis, when the total concentration as well as the carbonyl group distribution were monitored separately. Chromatographic separation of the different sample components was achieved when liquid chromatography at critical conditions (LC-CC) was used. For the first time, true high-temperature LC-CC methods were developed operating at a column temperature of 140°C. As the stationary phase, silica gel was used. Suitable mobile phases were binary mixtures of 1,2,4-trichlorobenzene or 1,2- dichlorobenzene with cyclohexanone. Using LC-CC, the samples were separated into the copolymer and the homopolymer fractions.

Publicly Available August 31, 2013

Starch-based multiphase polymer materials

Anna Kozłowska, Marek Kozłowski, Andrzej Iwańczuk

Article number: 054

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Abstract

Biocomposites prepared by melt blending were investigated. The blends were composed of synthetic and natural macromolecules, including poly(vinyl alcohol), aliphatic-aromatic polyester and thermoplastic starch. Mechanical properties of the composites, their microstructure, melt rheology and thermal characteristics are presented. Influence of water on the properties as well as the degradation rate of the materials has been estimated as a function of their composition. Such materials may find applications for packaging as well as in medicine and biology as polymeric scaffolds, drug delivery systems etc.

Publicly Available August 31, 2013

Structural study of semi-crystalline blends of poly(vinylidene fluoride) and poly(methyl methacrylate) by means of linear correlation and interface distribution functions

Mohamed Fatnassi, Fadhel Ben Cheikh Larbi, André Dubault, Jean Louis Halary

Article number: 055

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Abstract

In this article small-angle X-ray scattering (SAXS) is used to characterize the structural parameters of semi-crystalline blends of poly(vinylidene fluoride) (PVDF) and poly(methyl methacrylate). Different blend compositions from 100 to 50 wt.-% of PVDF were investigated. The samples were considered to be isotropic. As two-dimensional SAXS patterns with cylindrical symmetry were examined, a single direction in the SAXS pattern plane was chosen to collect and plot absolute intensities versus the scattering vector. Using the one-dimensional (linear) electron density correlation and interface distribution functions obtained, respectively, from the Fourier-transformed Lorentz-corrected experimental scattering intensity and from the interference function, structural parameters such as the minimal value and the most probable value of the long period, the average lamellar thickness, and the volume crystallinity were determined.

Publicly Available August 31, 2013

Molar mass characterization of hydrophilic copolymers, 2 Size exclusion chromatography of cationic (meth)acrylate copolymers

Martina Adler, Harald Pasch, Christian Meier, Raimund Senger, Hans-Günter Koban, Michael Augenstein, Günter Reinhold

Article number: 056

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Abstract

A robust and reproducible method for the molar mass analysis of cationic copolymers based on dimethylaminoethyl methacrylate or trimethylammonioethyl methacrylate and different (meth)acrylates has been developed. Size exclusion chromatography (SEC) using a novel polyester-based packing as the stationary phase and dimethylacetamide (DMAC) as the mobile phase yields highly accurate results for copolymers with an amino comonomer content up to 50 wt.-%. To suppress the different polar and ionic interactions between sample molecules, stationary phase and eluent, DMAC was modified with LiBr and tris(hydroxymethylamino) methane (TRIS). Calibrating the SEC system with poly(methyl methacrylate) of narrow polydispersity, molar masses were obtained that are in good agreement with viscosity data. Reproducibility and robustness of the novel method were proven by running samples for an extended period of two weeks.

Publicly Available August 31, 2013

Macrocyclic oligomers of an aromatic polyetherketone based on bisphenol A and difluorobenzophenone

Inessa Blagodatskikh, Artur Sakunts, Vera Shaposhnikova, Sergey Salazkin, Inga Ronova

Article number: 057

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Abstract

Cyclization reactions accompanying the nucleophilic displacement polymerization of bisphenol A and difluorobenzophenone (DFB) were studied. Size distribution and amounts of cyclic species were determined depending on the concentration and isomerism in DFB. Experimental cyclization constants were found to be consistent with the values calculated using Jacobson and Stockmayer’s theory for a freely rotating chain of virtual bonds in the case of 4,4’-DFB. For 2,4’-DFB, hindered rotation around some virtual bonds should be taken into account.

Publicly Available August 31, 2013

Structure and thermodynamic modelling of Pluronic L64 solutions

Naoufel Ghaouar, Adel Aschi, Mohamed Mondher Jebari, Abedelhafidh Gharbi

Article number: 058

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Abstract

The aim of the present work is to model structure and thermodynamic properties of Pluronic L64 solutions (triblock copolymer with hydrophilic ends and a hydrophobic middle). We first determined the micelle size by dynamic light scattering at various temperatures. This helps to understand the particle formation mechanism in solution and the interparticle interactions by following the virial coefficient as well as its temperature dependence. Two semi-empirical intermolecular potentials were tested to predict sample properties. First, we used a pure Lennard- Jones pair potential and then we introduced the Lu and Marlow (LM) contribution in its repulsive part. All quantities of interest were computed using the integral equation scheme with hybridized mean spherical approximation. We found that the LM contribution corrects structure and thermodynamic properties of the system by taking into account the effect of particle size.

Publicly Available August 31, 2013

Plasma-bonding of poly(dimethylsiloxane) to glass

Frank Katzenberg

Article number: 059

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Abstract

For the purpose of bonding poly(dimethylsiloxane) (PDMS) to glass, both components’ surfaces were treated with low-pressure oxygen plasma, indirect corona or simply with an oxygen-rich butane gas flame. In the case of low-pressure oxygen plasma treatment, the process parameters were varied and optimized with the consequence that the achieved adhesion between PDMS and the glass substrate was so strong that the PDMS could not be peeled off the glass slide without damaging the elastomer.

Publicly Available August 31, 2013

Magnetic poly(glycidyl methacrylate) microspheres for Campylobacter jejuni detection in food

Daniel Horák, Igor Hochel

Article number: 060

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Abstract

A sandwich enzyme labelled immunoassay (ELISA) has been developed for the detection of Campylobacter jejuni in food using magnetic poly(glycidyl methacrylate) (PGMA) microspheres as an alternative solid phase. The microspheres ( c . 2.5 μm in diameter) were prepared by dispersion polymerization in the presence of carboxymethylcellulose-coated Fe 3 O 4 - obtained by precipitation of Fe(II) and Fe(III) salts with aqueous ammonia - finely dispersed in ethanol/water solution using poly(vinylpyrrolidone) and 2,2’-azoisobutyronitrile as stabilizer and initiator, respectively. PGMA microspheres were ammonolyzed and the antibody against Campylobacter jejuni was immobilized via the 2,4,6-trichloro-1,3,5-triazine method. The optimal concentration of the second hen IgY was 50 μg/ml and the optimal concentration of the labelled antibody (rabbit anti-hen IgY immunoglobulin-horseradish peroxidase complex) reached 4 μg/ml. The detection limit of the assay was 4.8⋅10 6 cfu/ml. A limited number of artificially contaminated and uncontaminated food samples have been tested. Only one false-negative and one false-positive result (out of 18) were observed.

Publicly Available August 31, 2013

Coagulation kinetics and the stability of surfactant-free emulsion-polymerised latexes

E. Rotimi Sadiku, Ron D. Sanderson

Article number: 061

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Abstract

The stability factor of styrene/sulfopropyl methacrylate (styrene/SPM) and styrene/3-[ N , N -dimethyl- N -(methacryloxyethyl)ammonium]propane sulfate (styrene/ SPE) latexes was studied using the classical Derjaguin-Landau-Verwey-Overbeek (DLVO) theory and the critical coagulation concentration, CCC, was deduced for the latexes. Photon correlation spectroscopy was used to study ionic stabilities. The stability factor was determined as the ratio of the rate constant for rapid coagulation to that of slow coagulation, obtained from the coagulation kinetics data. The log-log plot of the stability factor, W , as a function of NaCl electrolyte concentration shows an asymptotic decrease in W of both latexes. DLVO theory was successfully employed, whereby the characteristic properties of the diffuse electric double layers or the Stern layers around latex particles in terms of their Hamaker constants and diffuse potentials were determined. The electric double layer thickness decreases with increasing NaCl concentration. Stability curves revealed a higher CCC value for the styrene/SPM latex than for the styrene/SPE latex, which is in accordance with the higher surface charge density and an indication of a better stability.

Publicly Available August 31, 2013

Extraction and characterization of polysaccharides from Mesembryanthemum crystallinum

Nour H. M’sakni, Hamouda Zayane, Hatem Majdoub, Claudine Morvan, Sadok Roudesli, André Deratani

Article number: 062

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Abstract

Water-soluble polysaccharides were isolated from Mesembryanthemum crystallinum . Two methods were applied, based (i) on the extraction in hot water (for fresh and dry plants, FP and DP) and (ii) on freeze-thawing of fresh plants (FT). Each fraction was purified by precipitation in ethanol followed by ultrafiltration of recovered solids dissolved in water through a membrane with a molecular weight cut off of 100 000. Elemental analysis demonstrated that the extracted products were polysaccharides exempt from proteins. The yield relative to the corresponding dry matter varied from 1.6 to 3% depending on the starting sample and the extraction process. Obtained products were characterised by their structural (sugar composition, degree of methylation (DM) and acetylation, molar mass of acid equivalent unit) and macromolecular characteristics (molar mass and intrinsic viscosity). A galacturonic-acid content larger than 65% and a DM value of c . 40% showed that the isolated polysaccharides belong to the fairly methylated pectin class. FP and FT structures consisted of the two blocks homogalacturonan (HG) and rhamnogalacturonan-I (RG-I) with relative proportions of 62 - 68% and 29 - 34%, respectively. They showed very similar physicochemical behaviour. On the other hand, DP exhibited significant differences in the chemical structure (50% HG and 46% RG-I blocks) and physical properties, indicating that partial degradation of HG moieties occurred during plant drying.

Publicly Available August 31, 2013

Preparation of fluorescent polymer particles by emulsion polymerization

Shunchao Gu, Naoto Anzai, Daisuke Nagao, Yoshio Kobayashi, Mikio Konno

Article number: 063

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Abstract

Core-shell type fluorescent polymer particles were produced in multi-step emulsion polymerization. Cross-linking was introduced to the shell to suppress leakage of fluorescent dyes contained in the core particles. First, fluorescent polymer particles were synthesized by emulsion copolymerization of styrene (St) and butyl acrylate (BA) with an anionic surfactant (SE1025A) initiated by ammonium persulfate (APS) in the presence of pyrene. The concentrations of St, BA, SE1025A and APS were 550, 89, 8.2 and 5 mol/m 3 water, respectively. Then the fluorescent particles were covered with cross-linked polymer by emulsion copolymerization of St, BA and divinylbenzene (DVB) with SE1025A emulsifier. In the polymerization, a mixture of St, BA, SE1025A and DVB was added dropwise to the reaction system. The average size of cross-linked fluorescent particles ranged from 50 to 70 nm. The fluorescence intensity of the particles prepared in a pyrene concentration range of 8 - 20 mol/m 3 water increased linearly with pyrene concentration. Fluorescence intensities of the particles prepared with and without DVB were also measured. The cross-linked polymer formed by DVB addition drastically suppressed the intensity drop caused by dye leakage almost to one-third of the intensity drop measured for particles prepared without DVB addition.

Publicly Available August 31, 2013

Power-law distribution of molecular weights of nonlinear emulsion polymers

Hidetaka Tobita

Article number: 064

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Abstract

It is shown that power-law distributed polymers can be synthesized via nonlinear emulsion polymerization. Theoretical simulation results demonstrate that emulsion polymers formed with polymer transfer reactions during interval II approach a power-law distribution as polymerization proceeds. The exponent α of the weight fraction distribution, W ( M ) ~ M -α , satisfies the simple relationship α = 1/ P b , where P b is the probability that the chain end is connected to a backbone chain. This relationship can be used to estimate the polymer transfer constant on the basis of the measured molecular weight distribution. The branched polymer structure is significantly different from randomly branched polymers. The expected branching density of the large-polymer limit is equal to that for P b = 1 of randomly branched polymers, irrespective of the magnitude of P b in the emulsion polymers. A preliminary investigation shows that power-law distributed polymers can also be synthesized via crosslinking emulsion polymerization.

Publicly Available August 31, 2013

Synthesis and characterization of novel organosoluble aromatic copolyimides

Jintian Yang, Wei Huang, Yongfeng Zhou, Deyue Yan, Xiaohang Wang

Article number: 065

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Abstract

A series of novel aromatic copolyimides was synthesized from pyromellitic dianhydride with the commercial diamine 4,4’-methylenebisaniline (MBA) and the diamine 4,4’-methylenebis(2 -tert- butylaniline) (MBTBA) specially designed by ourselves. The solubility of the copolyimides in conventional solvents decreased with the mole ratio of MBTBA to MBA. When MBTBA/MBA was larger than 8/2, the copolyimides are soluble in low boiling point solvents (such as chloroform and tetrahydrofuran) and can form a transparent, flexible, tough film by solution casting. When MBTBA/MBA was between 7/3 and 5/5, the copolyimides are only soluble in dipolar aprotic solvents (such as dimethylformamide and N -methyl-2-pyrrolidone) and form films, too. The copolyimide was precipitated in m- cresol in the polymerization process when MBTBA/MBA was lower than 5/5. The number-average molecular weights of the soluble copolyimides measured by gel permeation chromatography were larger than 5.0·10 4 and the polydispersity index was higher than 1.5. Only one glass transition of these copolyimides was detected at around 350°C. The copolyimides did not show appreciable decomposition up to 400°C under air and 550°C under nitrogen, and their thermal stability increased a little with the introduction of MBA into the polymer chains.

Publicly Available August 31, 2013

Thermodynamic and electrochemical study of multicomponent polymer complexes of varying composition

Mamta Sharma nee Chhabra, Sandeep Sharma

Article number: 066

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Abstract

Multicomponent complexes of varying composition have been prepared from poly(methacrylic acid -co- acrylamide), poly(ethyleneimine) and poly(vinylpyrrolidone). Stability constants and related thermodynamic parameters have been determined. Interpretations have been sought in terms of secondary binding forces and their magnitude.

Publicly Available August 31, 2013

Adsorption of monodisperse polybutadienes on carbon black, 3 Displacement of pre-adsorbed molecules by the same polymer. Conformational and molecular weight effects

Kathy Vuillaume, Bassel Haidar, Alain Vidal

Article number: 067

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Abstract

Displacement of pre-adsorbed macromolecules by the same polymer, polybutadiene, of the same or of different molecular weight was studied in solution and in the bulk. The effect of polymer concentration on pre-adsorption and displacement processes was determined. Displacement was investigated by gel permeation chromatography and by determination of the amount of bound polymer before and after displacement. A conformational factor was established as a major driving force - besides molecular weight - in the displacement process. Polymer chains adsorbed in flat conformation had the highest adsorption stability and could not be displaced by any other molecular weight of the same polymer.

Publicly Available August 31, 2013

Microwave-assisted synthesis of channel-containing polymeric materials

Michael Klink, Ute Kolb, Helmut Ritter

Article number: 068

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Abstract

Iron shows fast heat development under microwave (MW) irradiation. This property was used to start polymerization reactions on the surface of iron fibres. MW irradiation of metal fibres, which are located in a monomer solution consisting of methyl methacrylate, ethylene glycol dimethacrylate, N , N’ -azoisobutyronitrile and toluene led to the formation of polymer on the metal fibre surface. After dissolving the covered iron component in hydrochloric acid, a channelcontaining polymeric material was obtained. Scanning electron microscopy showed a smooth material with rough inner channels. These internal surface structures were caused by the rough surface of the metal fibres.

Publicly Available August 31, 2013

Carbon-chain polymers ‘grafting from’ inorganic nanoparticles

Peng Liu

Article number: 069

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Abstract

‘Grafting from’ methods can achieve higher percentages of grafting than ‘grafting to’ methods in the preparation of carbon-chain polymer grafted inorganic nanoparticles (CCP-INs). ‘Grafting from’ methods - such as one-pot method, macro-monomer, macro chain transfer agent, macro-initiator, and macro-iniferter methods, used for the preparation of CCP-INs in our laboratory in the recent years - are reviewed and the grafting parameters are compared. Characterization of the CCP-INs is also described.

Publicly Available August 31, 2013

Microwave-assisted nitroxide-mediated polymerization of alkyl acrylates

Mark Leenen, Frank Wiesbrock, Richard Hoogenboom, Ulrich S. Schubert

Article number: 070

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Abstract

Nitroxide-mediated polymerizations of methyl and tert -butyl acrylate were performed in a single-mode microwave reactor at 120°C. The polymerizations could be carried out in a controlled way in concentrated solution (approx. 50 wt.-% of monomer) up to monomer conversions of around 90%. Monomer conversion followed first-order kinetics in the case of tert -butyl acrylate. For methyl acrylate, it seems that the kinetics obeyed the persistent radical effect. The polymers obtained from this controlled radical polymerization technique exhibited narrow molecular weight distributions (indicated by polydispersity indices below 1.3).

Publicly Available August 31, 2013

Drug-loaded ultrafine poly(vinyl alcohol) fibre mats prepared by electrospinning

Chunxue Zhang, Xiaoyan Yuan, Lili Wu, Jing Sheng

Article number: 071

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Abstract

Submicron poly(vinyl alcohol) (PVA) fibre mats embedded with Aspirin and bovine serum albumin (BSA) were prepared by electrospinning of their aqueous solutions. Fibre morphology was investigated by scanning electron microscopy. The composition of the fibre mats was characterized by Fourier transform IR spectroscopy and X-ray photoelectron spectroscopy. The in vitro drug release was investigated by immersing the fibre mats in phosphate buffer solution at 37°C. Results indicated that the morphology of fibre mats was influenced by the amount of drug, and more beaded and irregularly shaped fibres were found with increasing drug amounts. There were drug molecules distributed on the surface of the PVA fibres. Studies of in vitro drug release showed that both Aspirin and BSA were released more quickly from PVA fibre mats than from PVA films because of the large surface area and high porosity of the fibre mats.

Publicly Available August 31, 2013

COPOINT – a simple computer program to determine copolymerization parameters by numerical integration

Uwe Beginn

Article number: 072

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Abstract

A computer program is introduced that evaluates the parameters of binary copolymerizations from comonomer/copolymer composition data as obtained from polymerization experiments with finite monomer conversion. The program numerically integrates a given copolymerization equation in its differential form and can be applied to a broad variety of functions. Copolymerization parameters are obtained by minimizing the sum of square differences between measured and calculated polymer compositions with respect to the copolymerization parameters. Errors of the fitted parameters are estimated from the statistical error of the sum of square differences, as well as from a quadratic approximation of this sum in the vicinity of the optimized values of the copolymerization parameters.

Publicly Available August 31, 2013

Antimicrobial activity of polystyrene particles coated by photo-crosslinked block copolymers containing a biocidal polymethacrylate block

Sandrine Lenoir, Christophe Pagnoulle, Christophe Detrembleur, Moreno Galleni, Robert Jérôme

Article number: 073

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Abstract

A commercially available poly(ethylene -co- butylene) copolymer, endcapped by a short polyisoprene block and a hydroxyl group (PI -b- PEB-OH), has been derivatized into a macroinitiator for atom transfer radical polymerization (ATRP) by esterification of the hydroxyl end-group by an activated bromidecontaining acyl bromide. Two types of triblock copolymers, PI -b- PEB -b- poly- (dimethylaminoethyl methacrylate) (PDMAEMA) and PI -b- PEB -b- poly[2-( tert- butylamino) ethyl methacrylate] (PTBAEMA), have been synthesized and used to coat polystyrene particles. These coatings have been permanently immobilized by UV cross-linking of the isoprene units. They exhibit a biocidal activity against Gramnegative bacteria either intrinsically in case of the PTBAEMA block or upon quaternization of the PDMAEMA block by octyl bromide. The antimicrobial activity is directly related to the concentration of coated PS particles in the medium.

Publicly Available August 31, 2013

Surface functionalization by smart binary polymer brushes to tune physico-chemical characteristics at biointerfaces

Petra Uhlmann, Nikolay Houbenov, Sergiy Minko, Manfred Stamm

Article number: 074

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Abstract

Polymer brushes consist of an assembly of polymer chains that are attached by one end to the surface with sufficient grafting density. Binary brushes constituted from two incompatible polymers can be used in the form of ultrathin polymeric layers as a versatile tool for surface engineering to tune physicochemical surface characteristics as wettability, surface charge, chemical composition or morphology, and furthermore to create responsive surface properties. It is also possible to fix surface structures obtained in this way by (photo)crosslinking of the layers. Mixed brushes of oppositely charged polyelectrolytes are representing a special case of responding surfaces, which are sensitive to changes of the pH in aqueous environment. It is shown that structural changes occur in the plateau region of the adsorption isotherm of a model protein and that changes of the pH also cause changes in the structure of the adsorbed protein layer.

Publicly Available August 31, 2013

Self-organization of poly(N-isopropylacrylamide)-carrying microspheres into two-dimensional colloidal thin films

Sakiko Tsuji, Haruma Kawaguchi

Article number: 075

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Abstract

A simple method to fabricate colloidal thin films with periodical structures was investigated. In this study, poly( N -isopropylacrylamide) (PNIPAM) microgel and polystyrene particles with PNIPAM chains on the surface (hairy particles) are used as components. Aqueous dispersions of these PNIPAM-carrying particles spontaneously form monolayers as water evaporates. After the medium is completely evaporated, periodical structures remain on the substrate. This paper focuses on the effect of graft chain density of the hairy particles on film formation.

Publicly Available August 31, 2013

Surface sulfate groups on poly(methyl methacrylate) and poly(vinyl acetate) particles from soap-free emulsion polymerization

Tadanobu Saiga, Atsushi Suzuki, Kenji Kikuchi, Takuji Okaya

Article number: 076

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Abstract

The amounts of sulfate groups on the particle surfaces of poly(methyl methacrylate) (PMMA) and poly(vinyl acetate) (PVAc) obtained in soap-free emulsion polymerization were determined. Polymerization was carried out at low monomer concentration using ammonium persulfate as an initiator. After the ionexchange procedure, conductometric titration was carried out. Amounts of surface sulfate groups were lower and particle diameter was larger in the PMMA system compared with PVAc. A large and remarkable difference appeared in the ratio of surface sulfate groups to decomposed sulfate radicals, viz. 90% for the PVAc system and 50% for PMMA. The ratios of sulfate groups per polymer molecule on PMMA and PVAc particles (functionality) were calculated. The functionality of the PMMA system was 70% of the theoretical value, while it was close to 100% in the PVAc system. This large difference might arise from the weak reactivity of the sulfate radical with MMA compared with that of VAc, due to the strong electrophilic nature of the radical. A side reaction of the sulfate radical with MMA is assumed. On the basis of these experimental results, the instability of the emulsion polymerization of acrylic monomers using poly(vinyl alcohol) (PVA) as a protective colloid is discussed in terms of the instability of the soap-free particles formed after the consumption of free PVA in water by the grafting reaction.

Publicly Available August 31, 2013

Bis(vinylcyclopropane) and bis(methacrylate) monomers with cholesteryl group for dental composites

SooWhan Choi, Anahita Hessamian, Monir Tabatabai, Urs Karl Fischer, Norbert Moszner, Helmut Ritter

Article number: 077

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Abstract

Novel bis(vinylcyclopropane)-based monomers with cholesteryl group and high molecular weight were prepared. The phase behaviour of the synthesized monomers was investigated. The obtained macromonomers showed a polymerisation shrinkage that was significantly lower compared to dimethacrylates used in dental composites.

Publicly Available August 31, 2013

Determination of chemical composition and molar mass distribution of random styrene-ethyl acrylate copolymers by high-throughput liquid chromatography

Iván García Romero, Mubasher Ahmed Bashir, Harald Pasch

Article number: 078

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Abstract

Synthesis and characterization of random copolymers by spectroscopic and chromatographic techniques are normally slow and expensive because most measurements are conducted consecutively and no high-throughput techniques are used. In the present work parallel synthesis and high-throughput analytical techniques for random styrene-ethyl acrylate copolymers were developed. With combinatorial methods, high-throughput instruments and a better design of experiments, the molar mass and chemical composition analyses were carried out simultaneously with time savings of more than 90% as compared to conventional set-ups. The chemical heterogeneity of high-conversion styrene-ethyl acrylate copolymers was determined successfully by fast gradient HPLC. Determination of the average composition was carried out via selective UV detection in size exclusion chromatography. The results were verified by 1 H NMR and calculations based on the copolymerisation parameters. Differential scanning calorimetry and optical microscopy techniques were used for determination of the phase separation behaviour of the copolymers and correlated with the chemical heterogeneity.

Publicly Available August 31, 2013

Facile synthesis of potato starch sulfate magnesium salts

Hanna Staroszczyk, Piotr Tomasik

Article number: 079

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Abstract

Potato starch blended with MgSO 4 and conc. H 2 SO 4 - Mg(HSO 4 ) 2 generated in situ - forms directly starch sulfate magnesium salts. Properties of the products depend, first of all, on whether convectional heating (60 - 70°C for 1 h) or microwave heating for either 30 min at 180 W or 5 min at 300 W is applied. Starch monoester and crosslinking diester are formed. The products are up to 95% watersoluble. They were characterized by means of thermal gravimetry and differential thermogravimetry, FTIR spectroscopy, and elemental analysis for Mg. Resulting products are potential plasticisers for cement, mortar, concrete, or other products containing hydraulic binders.

Publicly Available August 31, 2013

Kinetics and mechanism of miniemulsion polymerization of a sparingly water-soluble fluoro monomer

Kiyoshi Suzuki, Yasutaka Yamada, Kazumi Fujita, Mamoru Nomura, Hideya Saito

Article number: 080

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Abstract

In order to clarify the kinetics and mechanism of miniemulsion polymerization of a sparingly water-soluble monomer, the miniemulsion polymerization of 1,1,2,2-tetrahydroperfluorodecyl acrylate was conducted at 50°C using potassium persulfate as initiator and sodium dodecyl sulfate as emulsifier, respectively. It was found that the rate of polymerization was proportional to the 0.65 power of the initial initiator concentration and to the 0.30 power of the number of miniemulsion droplets (latex particles). It is pointed out that the kinetics of this polymerization system may be subject to the modified case III kinetics of emulsion polymerization with predominant bimolecular termination in the aqueous phase.

Publicly Available August 31, 2013

Characterization, structural transitions and properties of a tightly crosslinked polythiourethane network for optical applications

Boris Jaffrennou, Nicolas Droger, Françoise Méchin, Jean-Louis Halary, Jean-Pierre Pascault

Article number: 081

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Abstract

A new polythiourethane thermosetting system based on a diisocyanate and a trithiol was studied. After characterization of the reactive species, two critical temperatures, namely T g∞ (maximum glass transition temperature of the thermosetting system) and gel T g ( T g of the material at the gel point), were determined. The conversion at gel point was also determined and compared to the theoretical prediction. Two different characteristics of the evolution of a reactive system, T g and conversion x as a function of time, were related. This is of particular interest for understanding the curing process, especially when non-isothermal cure schedules are used. Viscoelastic and plastic properties were investigated, with the aim of establishing connections between the chemical structure and properties through detailed analysis of the polymer chain motions (β and α relaxations). Measurements of the storage modulus at the rubbery plateau and of the critical strain intensity factor K Ic complete the study.

Publicly Available August 31, 2013

A highly efficient, solvent-free and energy-effective method of cellulose acetylation

Abdelmajid Memmi, Robert Granet, Yves Champavier, Pierre Krausz

Article number: 082

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Abstract

Acetylation of cellulose by acetic anhydride was found to be catalysed quantitatively by iodine under solvent-free conditions at room temperature. Cellulose acetates were characterised by 1H NMR spectroscopy.

Publicly Available August 31, 2013

Poly(L,L-lactide) and poly(L,L-lactide-co-glycolide) microparticles by dialysis

Mariusz Gadzinowski, Stanislaw Sosnowski, Stanislaw Slomkowski

Article number: 083

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Abstract

Formation of poly(L,L-lactide) (PLLA) and poly(D,L-lactide -co- glycolide) (PLGA) microparticles by dialysis from 1,4-dioxane, tetrahydrofuran (THF), acetonitrile, dimethyl sulfoxide (DMSO), and dimethylformamide (DMF) against water has been investigated. In some instances microparticles were obtained from a mixture of the above-mentioned polyesters and PLLA -block- polyglycidol -block poly( ethylene oxide) triblock copolymer containing a hydrophobic PLLA block as well as hydrophilic polyglycidol and poly(ethylene oxide) blocks, the former with functional -OH groups. The effects of the nature of polyester, solvent and concentration of triblock copolymer on particles morphology, size, size distribution, and degree of crystallinity have been determined. Dialysis of PLGA yielded particles in the form of microspheres regardless of the solvent. Diameters of these particles were in the range of 0.36 - 1.77 μm and particles’ diameter polydispersity (D w ̅/D n̅ ) varied from 1.37 to 2.04, depending on the solvent. In the case of PLLA, microspheres were obtained only by dialysis from 1,4-dioxane solutions. Dialysis of PLLA solutions in THF, acetonitrile and DMF yielded particles in the form of microcrystals. In the case of dialysis of PLLA solutions in DMSO, the product was in form of crystalline flakes of c . 1 μm thickness. Microspheres composed of PLGA were amorphous. The degree of crystallinity of microparticles from PLLA was in the range of 39% - 72%.

Publicly Available August 31, 2013

Synthesis and characterization of 4- and 6-arm star-shaped poly(ε-caprolactone)s

Michael A. R. Meier, Ulrich S. Schubert

Article number: 084

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Abstract

Star-shaped poly(ε-caprolactone) (PCL) polymers were synthesized and fully characterized by gel permeation chromatography, matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF MS) as well as 1 H NMR spectroscopy. First a series of four-armed PCLs with different molecular weights was prepared and analyzed with the mentioned analytical techniques revealing that the applied ring-opening polymerization was controlled and defined star-shaped polymers could be synthesized. Subsequently, also the synthesis of six-armed PCL polymers was investigated with the conclusion that also these starshaped polymers could be prepared in a controlled fashion.

Publicly Available August 31, 2013

Morphology of nanocomposites from ethylene-acrylic acid copolymers

Pierluigi Magagnini, Sara Filippi, Cristina Marazzato, Francesco P. La Mantia, Liliya I. Minkova

Article number: 085

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Abstract

New nanocomposites have been prepared by melt-compounding from commercial ethylene-acrylic acid copolymers (EAA) of different molar mass, molecular structure (branched or linear) and AA concentration, and a Zn-ionomer, with three commercial clays containing different proportions of the same organic modifier (dimethyldi(hydrogenated tallow)ammonium ion). Their morphology has been preliminarily investigated by X-ray scattering and transmission electron microscopy. The nanocomposites showed disordered intercalated morphology, with an expansion of the average gallery height, which appears to depend quite strongly on the molecular architecture of the EAA, whereas the other investigated variables, including the excess of surfactant used to organically modify the silicate, have negligible effect.

Publicly Available August 31, 2013

Gelation of thermoplastic polyurethane/2-butanone solutions

Sonia Florez, María Eugenia Muñoz, Anton Santamaría

Article number: 086

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Abstract

New features of thermoplastic polyurethane (PUR)/2-butanone gels are investigated, using dynamic viscoelastic measurements and differential scanning calorimetry. The work is focused on the effect of the hard-segments content on the gelation process. In the case of PUR with the highest hard-segment fraction (30%), soft segments are not able to crystallize on cooling from solution; consequently, gels are not formed. The copolymer with the lowest hard-segment content (12%) gives the shortest gel times. This is attributed to the low solution viscosity of this copolymer, which enhances the crystallization rate. All gels melt at 7°C, giving rise to a viscoelastic solution in a thermoreversible process. The critical gelation concentration is below the critical concentration for polymer chain entanglements.

Education

Publicly Available August 31, 2013

Continuous Addition Polymerization

Uwe Beginn

Article number: E_003

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Abstract

Free- and controlled radical polymerizations have become standard reactions in the research laboratory to prepare a large variety of homo- and copolymers. Hence, the synthetic polymer chemist is frequently asked to supply a colleague or a project partner with 10 - 20 g of some (co)polymer. The usual mode of action is the "batch polymerization": Solvent, initiator and monomers are mixed and heat under an inert atmosphere until (almost) full conversion of the monomer has been achieved. Sometimes the researcher is not aware the fact, that this simple procedure is ineffective when used to prepared larger quantities of homopolymers and it will produce a messy product in many copolymerization reactions.

About this journal

e-Polymers is an open access, single-blind peer-reviewed scientific journal. The aim of e-Polymers is to publish, in an ongoing way, pure and applied polymer-science-related original research articles, reviews, and feature articles. It includes synthetic methodologies, characterization, and processing techniques for polymer materials. Reports on interdisciplinary polymer science and on applications of polymers in all areas are welcome.

In 2013 e-Polymers has been transferred from the e-Polymer Foundation to the scientific publisher De Gruyter. Prof. Seema Agarwal and Prof. Andreas Greiner took over as Editors-in-Chief. e-Polymers is dedicated to serve the polymer community and will continue publishing scientific contributions on highest possible standards.

The present Editor-in-Chief, Prof. Seema Agarwal, would like to thank the authors, the reviewers, the editorial staff, the advisory board, and the supporting organization that made e-Polymers a successful and sustainable scientific journal of the polymer community. The Editors of e-Polymers feel very much engaged to provide best publishing services at the highest possible level.

Topics

Pure and Applied Polymer Science
Organic Chemistry
Industrial Chemistry
Polymer Science and Technology

Article formats
Research Article, Review Article, Rapid Communication, Erratum

Information on submission process

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Special Issues:

"Biodegradable and bio-based polymers: Green approaches"
Guest Editors: Dr. Kumaran Subramanian (Sathyabama Institute of Science and Technology, Jeppiaar Nagar, India), Prof. A. Wilson Santhosh Kumar (AMITY University, Mumbai, India), and　Dr. Venkatajothi Ramarao (The Copperbelt University, Ndola, Zambia)

Submission deadline: August 31, 2023

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