Open Access Published by De Gruyter

Volume 2013 Issue 1

August 2013

Issue of e-Polymers

Submit manuscript

Contents
Journal Overview

Open Access August 21, 2013

Modulation of the electrochemical properties of SBS-based anionic membranes by the amine molecular structure

Antonio Filpi, Massimiliano Boccia, Andrea Pucci, Francesco Ciardelli

Page range: 1-14

More Download PDF

Abstract

In this work, different amines (bifunctional, as diazabicyclo[2.2.2]octane (Dabco) and monofunctional, as N-methylimidazole or trimethylamine) were utilized for the amination of benzyl chloride-grafted polystyrene-b-poly(butadiene)-bpolystyrene triblock copolymers (SBS-g-VBC). The use of Dabco solutions in mixture with variable amounts of monoamine or at different concentration allowed to modulate the degree of crosslinking of the SBS-based membranes and their electrochemical parameters. More specifically, tuning Dabco concentration permitted the reduction of water uptake without significantly affecting ionic conductivity.

Open Access August 21, 2013

Effect of an anionic surfactant upon the viscosity of poly(ethylene glycol) in dilute solution

Xiaoming Chen, Yi Ding, Mingdi Yang

Page range: 15-19

More Download PDF

Abstract

The reduced viscosity of poly(ethylene glycol) in solutions containing a certain concentration of sodium bis(2-ethylhexyl) sulfosuccinate (AOT) was measured. It has been found that the Huggins coefficient k H and the intrinsic viscosity [η] of polymer solution are very sensitive to the concentration of surfactants, CAOT, in solution. If CAOT is less than CMC, the critical micelle concentration of AOT, k H decreases and [η] increases rapidly with CAOT. On the other hand, if CAOT is greater than CMC, k H increases and [η] decreases rapidly with CAOT. The experimental results indicate that the inter- and intra-molecular association of poly(ethylene glycol) in solution is greatly associated with AOT interacted with polymer chain.

Open Access August 21, 2013

Synthesis, characterization, and drug delivery property of 2-N-carboxymethyl-6-O-diethylaminoethyl-chitosan

Aidi Zhang, Derun Ding, Jicun Ren, Xiangli Zhu, Youhong Yao

Page range: 20-31

More Download PDF

Abstract

A novel route is demonstrated for the synthesis of 2-N-carboxymethyl-6- O-diethylaminoethyl-chitosan (DEAE-CMC) by incorporation of carboxymethyl groups as hydrophilic moieties to the C2-NH 2 , and diethylaminoethyl groups as hydrophobic moieties to the C6-CH 2 OH of the structural unit of chitosan, via a protection-graft-deprotection procedure with benzaldehyde as protective agent. The structure, morphology, and thermal properties of the chitosan graft copolymers were characterized by means of FT-IR, 1 H NMR, SEM, TGA and DSC. Chitosan and its derivatives were used as carrier of model drug-Vitamin B 12 (VB12), and their controlled delivery behaviour in phosphate buffer solution (pH 7.4) were studied. The results show that the release rate of VB12 from the carrier of DEAE-CMC copolymer becomes much slower than that of chitosan in phosphate buffer solution.

Open Access August 21, 2013

Molecular dynamics simulations on dextran hydrogels

Jun Chen, Si-Min Zhou, Bao-Guang Ma, Li-Ming Zhang, Ju-Zhen Yi

Page range: 32-39

More Download PDF

Abstract

To probe the detailed structure of dextran hydrogels, periodical models for three dextran hydrogel systems with different dextran contents have been constructed and compared using molecular dynamic simulations. The software packages of Amorphous and Discover in Material Studio with COMPASS force field were used for the simulation. Energy minimization and geometry optimization were used to refine the models. In particular, the structure and dynamic movement of dextran chains which impose on water in the dextran hydrogel systems have been studied. The results show that in the physically crosslinked dextran hydrogels, KCl served as the crosslinker and it interacted with dextran via the oxygen atoms of hydroxyl groups in dextran ring. With increasing dextran content, the free volumes of the hydrogels and the diffusion coefficients of water in the hydrogel decrease. By the radial distribution analysis, the water in the hydrogel networks was found to interact with dextran via hydrogen bond and there are at least three kinds of water in the physically crosslinked dextran hydrogels. These results have a great significance for understanding the structure and properties of the hydrogel.

Open Access August 21, 2013

Evaluation of poly(methyl methacrylate) latex nanoparticles used in water-based drilling fluids

Xiaodong Bai, Xu Wang, Xiaolin Pu

Page range: 40-48

More Download PDF

Abstract

In the prospecting and drilling processes of gas and oil, if added into the drilling fluids, the latex nanoparticles can improve the performance of the drilling fluids. In this paper, methyl methacrylate (MMA) acts as a monomer and the combination emulsifier is a certain proportion of OP-10, RH and T-80. PMMA latex nanoparticles have been polymerized through the method called microemulsion polymerization. The conditions of methyl methacrylate microemulsion polymerization have been discussed and optimized. The dosage of emulsifier is 5 wt.%, polymerization temperature is 75 °C, and the stirring rate is 100 rpm. The particle shape, granularity distribution and molecular weight have been characterized by transmission electron microscope, laser particle size analysis device and gel permeation chromatography, respectively. The results indicate that the PMMA particles are ball like, showing average particle size of 65 nm, and that the MW is about 437,140. Results show that PMMA latex has strong inhibitive function on the shale swelling. When the latex is added into the drilling fluids, the filter loss decreases dramatically; and the PMMA latex drilling fluids system can be used when the temperature is below 180 °C.

Open Access August 21, 2013

A numerical study on deformation of Newtonian droplets through converging cylindrical dies

M. Mostafaiyan, M.R. Saeb, Z. Ahmadi, H.A. Khonakdar, U. Wagenknecht, G. Heinrich

Page range: 49-66

More Download PDF

Abstract

In this work, the dynamic deformation of a viscose Newtonian droplet passing through cylindrical converging dies has been studied. The changes in the interfacial area between two immiscible Newtonian fluids have been considered as a variable representing the time-dependent deformation of a circular droplet along converging dies. To do so, a surface tracking method has been incorporated into a finite element code, developed by the authors, which quantifies the deformation of the droplet through the converging path, and where the surface area of the deformed drop has been consequently chosen as a criterion for a two-phase interface. In this study, it has been revealed that by changing both rheological and geometrical parameters it is possible to manage the value of interface area between two phases. Ultimately, a unique curve is developed for each droplet to primary phase viscosity ratio which can correlate drop deformation with geometrical parameters.

Open Access August 21, 2013

Conductive regenerated silk fibroin composite fiber containing MWNTs

Negin Piri, Vahid Mottaghitalab, Shahram Arbab

Page range: 67-81

More Download PDF

Abstract

The electrically conductive regenerated silk fibroin (RSF) fiber containing multiwalled carbon nanotubes (MWNTs) was developed through wet spinning process. A general scheme used for extraction of RSF powder as biopolymer matrix for MWNTs conductive filler. The MWNTs inclusion demands for a sophisticated approach to prepare stable, exfoliated and well distributed filler in matrix solution. Dynamic Light Scattering (DLS) was utilized to show the ability of RSF in stabilizing of MWNTs throughout spinning solution. A non-Newtonian shear thinning behavior observed for RSF/MWNTs according to strong chain entanglement, whereas, the neat RSF solution shows a lower dependence on the shear rate. The scanning electron microscopy (SEM) images also confirmed the proper distribution of MWNTs as a continuous fibril media in the RSF matrix. The Fourier transform infrared spectroscopy (FTIR) demonstrated the role of MWNTs inclusion for increasing of the crystalinity compared to bare RSF fiber. The Raman spectra also confirmed the domination of RSF signatures by strong Raman bands of MWNTs most specifically in RBM region regarding to superior nanotube exfoliation. Moreover, the measurement of four-point probe electrical conductivity for different MWNTs content shows a maximum conductivity of 0.12 S/cm at percolation threshold. The higher thermal stability and greater crystalinity were also evidenced by DSC thermal analysis.

Open Access August 21, 2013

Application of high-resolution transmission electron microscopy and electron energy-loss spectroscopy in the characterization of polymer nanotubes

Lei Shang, Xiaoru Li, Yiqian Wang

Page range: 82-89

More Download PDF

Abstract

Polyamide 6 (PA6) and polystyrene (PS) nanotubes were successfully fabricated by polymer solution-wetting method. High-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD) and electron energy-loss spectroscopy (EELS) techniques were employed to investigate their crystallization phenomena. It has been found in HRTEM images that the crystalline lattice fringes are observed in some regions of the nanotube walls. XRD analysis showed that these two kinds of polymer nanotubes have a higher degree of crystallinity than that of the bulk materials. PA6 nanotubes dominate in γ phase while bulk PA6 present mainly in α phase. EELS has been used to determine the ratio of C=C and C-C in PS nanotubes, and our result is consistent with the theoretical calculation. HRTEM and EELS will shed light on the microstructural characterization of polymer nanotubes.

Open Access August 21, 2013

Synthesis of binary-patterned brushes by combining atom transfer radical polymerization and ring-opening polymerization

Aurore Olivier, Franck Meyer, Jean-Marie Raquez, Philippe Dubois

Page range: 90-98

More Download PDF

Abstract

This paper report the synthesis of binary-patterned brushes, combining two distinctive surface initiated-polymerizations (SIP) on the basis of different propagating species: the SI Ring Opening Polymerization (ROP) of L-Lactide (LLA) and SI atom transfer radical polymerization (ATRP) of N,N’-dimethylaminoethyl methacrylate (DMAEMA) on gold surface. First of all, a careful study of surfaceinitiated ROP of L-Lactide from hydroxyl end-group of thiol monolayer on gold surface as catalyzed by metal-free catalyst was carried out. The PLLA brushes synthesis was evaluated using two types of thiol monolayer and revealed the influence of ROP initiator chain length on the final thickness of the PLLA film. Combining the soft lithographic technique, microcontact printing, and the liquid phase deposition, the deposition onto specific micro-domains of both initiators was performed. The growth of PDMAEMA brushes and PLLA brushes was conducted by successive ATRP and ROP.

Open Access August 21, 2013

Effect of the boron presence on the properties of polyurethane foams obtained with hydroxypropyl derivatives of oxamide as the polyol components

Iwona Zarzyka

Page range: 99-114

More Download PDF

Abstract

The results of esterification of N,N'-bis(2-hydroxypropyl)oxamide (BHPOD) with the use of boric acid (BA) have been described. Subsequently hydroxypropyl derivatives of oxamide (OD) modified with boron as products of the reaction of BHPOD esterified boric acid with an excess of propylene carbonate (PC) have been obtained. Foamed polyurethane materials received with the use of these derivatives as polyol components and diisocyanate 4,4'-diphenylmethane exhibited higher thermal stability and compressive strength compared to the foams obtained with hydroxypropyl derivatives of OD which do not contain boron.

Open Access August 21, 2013

Preparation of poly(vinyl alcohol)/silica nanocomposties by sol-gel method

Yan-Na Zhao

Page range: 115-123

More Download PDF

Abstract

The poly(vinyl alcohol)/silica nano-composities hybrid membranes were prepared by co-hydrolysis and co-condensation of γ-glycidyloxypropyl trimethoxysilane (GPTMS) and tetraethoxysilane (TEOS) in poly(vinyl alcohol)(PVA) aqueous solution. The mechanical properties of hybrid membranes was studied, the result indicated that the well dispersion of nanoparticles was beneficial to the enhancement of the mechanical properties, and GPTMS could increase the miscibility of the polymer and SiO 2 . The membranes were characterized by scanning eletron microscopy (SEM) equipped with energy dispersive X-ray spectrometry (EDS), 29Si CP/MAS solid-state nuclear magnatic resonance (NMR). The EDS of poly(vinyl alcohol)/silica nano-composities showed that Si element had been grafted onto the chain of PVA. The 29 Si CP/MAS solidstate NMR spectra, 13 C CP/MAS Solid-state NMR spectrum and EDS confirmed that silica had been introduced into the chain of PVA. Latex particle size and morphology was observed by transmission electron microscopy (TEM) and dynamic light scattering (DLS). The TEM and DLS indicated that silica nanoparticles well and regularly dispersed in PVA solution and the average diameter of silica nanoparticles dispersed in PVA solution was about 58 nm.

Open Access August 21, 2013

Synthesis and characterization of novel polysiloxane based ABA-type triblock copolymers using ATRP

Rajan B. Bodkhe, Dean C. Webster

Page range: 124-134

More Download PDF

Abstract

Novel polysiloxane based ABA-type triblock copolymers having a secondary amine at the junction point were synthesized using a combination of ring opening equilibration polymerization (ROEP), Michael addition and atom transfer radical polymerization (ATRP). Polysiloxane based bifunctional ATRP macroinitiators were synthesized and subsequently used for controlled radical polymerization of t-butyl acrylate (t-BA) and sulfobetaine methacrylate (SBMA). Gel permeation chromatography (GPC) analysis of the triblocks based on t-BA showed high chain end functionality, due to the disappearance of peaks related to the macroinitiator. ROEP can be used to control the block length of the polysiloxane while ATRP can be used to control the chain length of the outer blocks, making the ABA- type triblock a unique material with secondary amine functionality which can be used for further reaction.

Open Access August 21, 2013

High performance of amidoxime/amine functionalized polypropylene for uranyl (VI) from aqueous solution

Fangting Chi, Jie Xiong, Sheng Hu, Jingwei Hou, Mei Gu, Jun Han

Page range: 135-143

More Download PDF

Abstract

Amidoxime-based adsorbents are widely investigated as the main adsorbent in the recovery of uranium from seawater. However, the adsorption rate and loading capacity of such adsorbents should be further improved due to the economic viability consideration. In this paper, the adsorption properties of amidoxime-based adsorbent were enhanced through the cografting of amino groups. The acrylonitrile (AN) and glycidyl methacrylate (GMA) were firstly cografted onto polypropylene fibers by preirradiation grafting technique. Then the cografted fibers were treated with ethylenediamine to convert GMA to amino group, following treated with hydroxylamine to convert AN groups to amidoxime (AO) group. Fourier transform infrared spectroscopy, scanning electron microscopy and contact angle measurement were used to characterize the structure of the adsorbent. The results showed that the amidoxime and amino groups had been successfully grafted onto the polypropylene fibers. For AO fiber, high adsorption rate was observed within the first 30 min and the plateau value of 42.3% uranium loading (0.0904mg/g) was reached at around 30 min. The AO/amine fibers exhibited a higher adsorption rate. The adsorption equilibrium for AO/amine fiber was attained within 20 min, resulting in the adsorption of 93.3% uranium loading (0.191mg/g). Additionally, AO/amine fibers can avoid pH reducing for better adsorption efficiency.

Open Access August 21, 2013

Unperturbed dimensions of polymers revisited through the blob theory: the viscometric expansion factor

Anastasios Dondos

Page range: 144-152

More Download PDF

Abstract

Plotting log([η]/M 1/2 ) versus log(N/N c ) where [η] is the intrinsic viscosity of the macromolecular chain of molecular mass equal to M and N/N c is the number of blobs of which this chain consists (N: the number of statistical segment of the chain and N c : the number of statistical segment of one blob), we obtain the unperturbed dimensions parameter of the blob, K θb . This graphical representation in this article is based on a modified, original equation of Han [6] based on the blob theory. The obtained value of K θb for a given polymer, dissolved in a good solvent, is lower than the unperturbed dimensions parameter, K θ , obtained for the same polymer in the Flory’s theta conditions. Having K θb < K θ we obtain for the viscometric expansion factors of a polymer, based on K θb or K θ , α ηb > α η . With the obtained values of αηb we find α ηb 3 /α s 2 α H ≈ 1, as predicted by Weill and des Cloizeauz [1], where using αη we obtain α η 3 /α s 2 α H ≈ 0.85 (α s and α H are the static and dynamical expansions factors).

Open Access August 21, 2013

Permeability characterization of hydroxypropylcellulose/ polyacrylonitrile blend membranes

Hui Li, Guo-li Gong, Tai-sheng Gong

Page range: 153-162

More Download PDF

Abstract

A series of blend membranes were prepared by immersion precipitation phase inversion method using hydroxypropylcellulose and polyacrylonitrile as raw materials. The effects of casting conditions on membrane’s characterization were studied. The properties of resulting blend membranes were that water flux decreased from 489 L·h -1 ·m -2 to 312 L·h -1 ·m -2 ; retention rate increased from 80.1% to 91.8%; and corresponding porosity presented increasing trend but changed little within the range of casting solution concentrations from 10 wt % to 16 wt %. The greater the mass fraction of HPC in casting solution, the greater the water flux of blend membranes. Prolonging the atmosphere exposing time, water flux increased from 268 L·h -1 ·m -2 about 20s to 372 L·h -1 ·m -2 about 60 s, then decreased to 340 L·h -1 ·m -2 about 75s. In addition, retention rate decreased from 91.2% to 81.3%. Porosity tend to decrease but changed a little. With the coagulation bath temperature rising, water flux of blend membranes increased from 306 L·h -1 ·m -2 about 20 °C to 429 L·h -1 ·m -2 about 35 °C, and corresponding retention rate decreased from 87.9% to 82.5%, porosity decreased from 80.23% to 68.26%.

Open Access August 21, 2013

Tuning of heavy metal removal efficiency from water via micro algae/hydrogel composites

Demet Aydınoğlu, Sinan Şen, Ekmel Helvacıoğlu, Turgut Nugay, Nihan Nugay

Page range: 163-179

More Download PDF

Abstract

A series of micro algea-based hydrogel composites were prepared from polyacrylamide and Spirulina (PAAm-sp). Free radical polymerization of acrylamide (AAm) in the presence of N,N-methylene bis-acrylamide (BAAm), as a crosslinker, and Spirulina microalgae in different loadings was conducted. Chromium metal adsorption capacity was determined with UV-VIS spectroscopy whereas mechanical performance of the resultant hydrogel composites was followed with uniaxial compression experiments. It has been found that efficiency can be tuned by Spiriluna composition in hydrogel. PAAm hydrogel composite having 0.5 % Spirulina had the maximum compression strength, good swelling in water as well as improved thermal stability due to the special and beneficial ‘fishnet morphology” observed via scanning electron microscopy (SEM). The observed high performance of this composition is proved to be due to this morphology where all potential binding sites are under receptive position for metal adsorption. Spirulina by itself in water can remove only about 2 % of its weight of Cr+3 ion , however in the hydrogel structure this removal increases up to 200 % which makes this biotechnological approach superior in the metal removal from the water.

Open Access August 21, 2013

Enantioselective analysis of naproxen using chiral molecular imprinting polymers based thin-layer chromatography

Fengyun Huangfu, Bing Wang, Juanjuan Shan, Zhiliang Zhang

Page range: 180-188

More Download PDF

Abstract

This paper describes a rational design and testing of molecularly imprinted polymers (MIPs) as chiral stationary phases of thin-layer chromatography (TLC) for enantiomeric purity of naproxen. Using D-naproxen as template, MIPs with particle size between 10~90 μm were prepared by precipitation polymerization in acetonitrile/methanol mixed solvent. The interactions between functional monomers and template were verified by UV absorption spectrometry. The morphology, particle size distribution and specific surface area of MIPs were also observed by scanning electron microscopy, particle size distribution meter and liquid nitrogen adsorption instrument, respectively. Binding capacities of MIPs had been studied by equilibrium binding assay. Preparation conditions of TLC and impact of acetic acid content on the separation of enantiomers were investigated. The results indicated that when acetic acid content was 4%, the racemates of templates were completely separated, and the chiral separation factor α was 1.58.

Open Access August 21, 2013

Controlled release of Capreomycin sulfate from pH-responsive nanocapsules

Olessya P. Loiko, Alex M. van Herk, Syed I. Ali, Meiram Zh. Burkeev, Yerkeblan M. Tazhbayev, Lyazzat Zh. Zhaparova

Page range: 189-202

More Download PDF

Abstract

The synthesis of polymeric nanocapsules loaded with the antituberculosis drug Capreomycin sulphate is presented in this work. The pHresponsive polymeric nanocapsules were successfully synthesized using the RAFT-based vesicle templating approach in the presence of Capreomycin sulphate. Anionic small polyelectrolytes comprising randomly distributed butyl acrylate and acrylic acid units were adsorbed on cationic vesicles of dimethyldioctadecyl ammonium bromide (DODAB). N,N-(dimethylamino)ethyl methacrylate (DMAEMA) and methyl methacrylate (MMA) or tertiary butyl methacrylate (tBMA) and MMA were used for the formation of the polymeric shells. Subsequently the tBMA was hydrolyzed to obtain negatively charged nanocapsules. The nanocapsule morphology for both approaches was characterized by DLS and TEM. The most stable hollow latex particles were obtained with the monomer composition of DMAEMA:MMA = 1:1. These nanocapsules were found to be colloidally stable and pH-responsive. The entrapment efficiency of drug determined by UV-Vis-spectroscopy was 70 %. The drug release rate from nanocapsules at pH 6.5 was found to be relatively fast (substantial release within one hour already), however we believe slower release can be achieved by using a thicker polymer shell.

Open Access August 21, 2013

Determination of the melting enthalpy of β phase of poly(vinylidene fluoride)

Arkadiusz Gradys, Pawel Sajkiewicz

Page range: 203-216

More Download PDF

Abstract

Wide Angle X-ray Scattering (WAXS), Differential Scanning Calorimetry (DSC) and Fourier Transform Infrared spectroscopy (FTIR) analyses of phase composition and of thermal properties of PVDF samples, crystallized at temperatures 27 - 155 °C by casting from N,N-dimethyl formamide (DMF) solution, are reported. Samples obtained at 27 oC contain only β crystal phase and with increase of casting temperature content of β phase decreases in favor of α phase. Evaluation of combined: phase content (WAXS) and melting heat (DSC), leads to two fold higher than for 100 % α phase value of 100% β melting enthalpy, ΔH β 0 = 219.7 J.g-1, which may be justified by strong polar interactions in β phase TTT conformation. The relation ΔHβ 0 > ΔH α 0 leads either to the thermodynamic stability of β phase in whole temperature range (if T mβ 0 ≥ T mα 0 ) or to the limited temperature range of thermodynamic stability of α phase (if T mβ 0 < T mα 0 ).

Open Access August 21, 2013

Rheological measurement of molecular weight distribution of polymers

Maryam Khak, Ahmad Ramazani

Page range: 217-228

More Download PDF

Abstract

This paper has described a method to obtain the molecular weight distribution (MWD) of polymeric materials from their rheological data. The method has been developed for linear polymers with log normal molecular weight distribution. The rheological data required to obtain the molecular weight distribution are the shear storage modulus,G' (ω) , and shear loss modulus,G" (ω) , extending from the terminal zone to the plateau region. For determining the molecular weight average, the method uses the relationship between stress moduli and relaxation spectrums, with the equation that connects dynamic rheological data with molecular weight distribution, and so it is not necessary to achieve the relaxation spectrums and the molecular weight distribution is obtained directly from dynamic shear experiments and it is one of the main advantageous of the proposed method. Comparison of calculated and experimental data obtained by GPC for five polypropylene samples produced in different conditions show that model can correctly predict molecular weight distribution for these types of polymers.

Open Access August 21, 2013

Electrospinning of polyvinyl butyral in different solvents

F. Yener, B. Yalcinkaya

Page range: 229-242

More Download PDF

Abstract

In this study we aimed at finding different solvents for PVB and determine the effect of concentration and solvents on electrospun polyvinyl butyral (PVB) nanofibers. Firstly, we solved PVB in isopropanol, n-butanol, dimethylformamide, ethanol and acetic acid in various concentrations. Later, we compared fiber characteristics for each solvent. We observed that with increasing concentration, the fiber diameter increased. Bead formation occurred in low concentrations and low viscosity of polymer solution. Each solvent has a different effect on nanofiber morphology. It is observed that fiber diameter and morphology is one of the parameters that can be controlled by solvent.

Open Access August 21, 2013

Intrinsic viscosity of PVP polymers in extremely diluted solutions

Jana Tothova, Vladimir Lisy

Page range: 243-248

More Download PDF

Abstract

In conventional viscometry studies an additional treatment of data is necessary in order to obtain the expected linear dependence of the reduced viscosity on concentration in extremely diluted polymer solutions. This work reports on the direct measurements of this dependence using a new Couette-type viscometer. The values of intrinsic viscosity and Huggins coefficient of the studied poly(N-vinyl-2-pyrrolidone) (PVP) water solution notably differ from the previous results obtained by the traditional capillary viscometers. From the obtained data the parameters used in the bead-spring theories of polymer universal behavior, such as the gyration radius and the longest relaxation time are calculated.

Open Access August 21, 2013

Condensation of α,ω-siloxane diols with aminoalkyl- (alkoxy)silanes

Magdalena Lubkowska, Wlodzimierz A. Stanczyk, Krystyna Rozga-Wijas

Page range: 249-260

More Download PDF

Abstract

Kinetics of condensation of individual siloxane diols HO[(CH 3 ) 2 SiO] x Si(CH 3 ) 2 OH (x=3,5,6 and 9) with aminoalkyl-alkoxysilanes (RO) 2 SiR’(CH 2 ) 3 NHR’’ (R = CH 3 , CH 2 CH 3 ; R’ = CH 3 , OR; R’’ = H, (CH 2 ) 2 NH 2 ) is described. The second order rate constants point to the significant effect of the siloxane diols chain length on reactivity, which increases for higher homologues (almost an order) of magnitude on coming from x=3 to x=9. The role of substituents at silicon atom is discussed. Three novel functional siloxane oligomers (substrates) are described and characterized.

Open Access August 21, 2013

Chain length distribution and kinetic characteristics of an enzymatically produced polymer

K.J.M. Mulders, H.H. Beeftink

Page range: 261-272

More Download PDF

Abstract

Non-processive enzymatic polymerization leads to a distribution of polymer chain lengths. A polymerization model was developed to investigate the relation between the extent of this distribution on one hand, and the polymerization start conditions and reaction kinetics on the other hand. The model describes changes in concentration of chains of length n as the result of two elongation reactions: elongation by monomer addition to length n-1 and elongation by monomer addition to length n. Polymerization reactions were assumed to be zero order in monomer concentration and to obey Michaelis-Menten kinetics with respect to polymer concentrations. In addition, the amount of enzyme available for each individual reaction (n → n+1) is assumed to be proportional to the concentration of polymer substrate of length n. The development of the shape of the chain length distribution was found to be independent of the value of the overall reaction rate constant; only the rate at which these shapes developed was influenced by the 1st-order rate constant. The value of the Michaelis parameter did affect the form of the chain length distribution curve since it affects the reaction order. An increase in reaction order was found to promote widening of the chain length distribution. Differences in kinetic parameters between the subsequent polymerization reactions, if any, were also found to have a large effect on the development of the chain length distribution. An increase in rate constants with chain length entailed a wider distribution; a more narrow distribution would require a decrease in rate constants with chain length.

Open Access August 21, 2013

Preparation and characterization of poly(3-hydroxybutyrate)/ Cloisite25A nanocomposites

Matko Erceg, Dražan Jozić

Page range: 273-284

More Download PDF

Abstract

Poly(3-hydroxybutyrate)/Cloisite25A (PHB/25A) nanocomposites were prepared by solution-intercalation method. The intercalation of PHB chains between the layers of Cloisite25A was observed by X-ray diffraction (XRD). Differential scanning calorimetry (DSC) and non-isothermal thermogravimetry (TG) analysis were performed to study the thermal properties, crystallization and the thermal degradation of the prepared nanocomposites. DSC analysis indicates that Cloisite25A acts as a nucleating agent and increases the crystallization rate of PHB, but due to intercalation reduces its overall degree of crystallinity. TG analysis shows that addition of Cloisite25A enhances the thermal stability of PHB.

Open Access August 21, 2013

Hydrogen effects in the polymerization of propylene with C₂ symmetric metallocene catalysts

Ismael Amer, Albert van Reenen

Page range: 285-292

More Download PDF

Abstract

Propylene was polymerized with two C 2 symmetric metallocene catalysts, ethylene bis(indenyl)zirconium dichloride and dimethylsilyl bis(2-methylbenz( e) indenyl) zirconium dichloride, in the presence of increasing amounts of hydrogen. The hydrogen influenced the molecular weight significantly, as was expected. The degree of isotacticity of the polypropylene was influenced by the level of hydrogen added during polymerization, and the amount and type of stereoerrors as determined by 13 C NMR increased as hydrogen levels were increased. Results indicated that efficiency of enantiomorphic site control is dependent on the length of the growing polymer chain during polymerization.

Open Access August 21, 2013

Preparation of syndiotactic polystyrene using novel monotitanocene with ortho-substituted phenoxy ligands

Ling Zhang, Shanshan Xiao, Shaowen Huang, Fangming Zhu, Qing Wu

Page range: 293-299

More Download PDF

Abstract

Four new Cp*Ti compounds with ortho-substituted phenoxy ligands for the syndio- specific polymerization of styrene were prepared by the reaction of various kinds of ortho- substituted phenol with Cp*TiCl 3 in the presence of triethylamine. Their catalytic properties for syndiospecific polymerization of styrene were investigated at different AlMAO/Ti ratio, different AlTIBA/Ti ratio and different polymerization temperature. All four compounds in the presence of cocatalyst methylaluminoxane (MAO) and triisobutylaluminum (TIBA) showed good performance at lower concentrations of titanium, MAO, and TIBA. Especially, ( Cp*Ti(OPhMe) 3 )/MAO system afforded syndiotactic polystyrene (sPS) with the highest activity and high molecular weight

Open Access August 21, 2013

Acicular precipitated calcium carbonate as inorganic whisker for reinforcing of polypropylene fibers

Roland Vogel, Regine Boldt, Marijan Vučak

Page range: 300-309

More Download PDF

Abstract

Acicular precipitated calcium carbonate (PCC) was used as appropriate inorganic whisker for improving the mechanical properties of melt spun polypropylene fibers. Nucleation effects of the PCC in dependence to concentration, surface coating and pre-shearing were analyzed. Melt-spinning experiments were carried out in order to determine the reinforcing effect.

Open Access August 21, 2013

Encapsulation of human serum albumin in submicrometer magnetic poly(lactide-co-glycolide) particles as a model system for targeted drug delivery

Quazi T.H. Shubhra, Hana Macková, Daniel Horák, Andrea Fodor-Kardos, Judit Tóth, János Gyenis, Tivadar Feczkó

Page range: 310-318

More Download PDF

Abstract

Two types of iron oxide nanoparticles were synthesized by coprecipitation of Fe(II) and Fe(III) chlorides: water-dispersible γ-Fe2O3 and organic solvent-dispersible oleic acid-coated Fe3O4 particles. The nanoparticles, together with human serum albumin (HSA) serving as a model for a protein-type drug, were then incorporated in poly(lactide-co-glycolide) (PLGA) particles using double emulsion solvent evaporation technique. Morphology, size and particle size distribution of the resulting particles was analyzed by electron microscopy and dynamic light scattering. Iron oxide and HSA encapsulating efficiency was determined by Prussian Blue staining and micro-BCA assay, respectively.

Open Access August 21, 2013

Preparation of ciprofloxacin-encapsulated poly-ε- caprolactone microcapsules by the solvent evaporation technique

Marta Przybyslawska, Aleksandra Amelian, Katarzyna Winnicka

Page range: 319-330

More Download PDF

Abstract

The objective of this study was to prepare ciprofloxacin (CIP) encapsulated poly-ε-caprolactone (PCL) microcapsules by the single emulsion oilin- water (o/w) solvent evaporation method. The obtained microcapsules were characterized for size, morphology, drug loading and entrapment efficiency. The physical state of microcapsules was determined by differential scanning calorimetry (DSC) and thermogravimetric analysis (TG). Storage stability, the in vitro drug release and mathematical modeling of drug release were also tested. It was found that obtained microcapsules had spherical shape and their size range was from 57.5 μm to 234.7 μm. The drug loading of microcapsules was from 1.72% to 11.02%. The optimal conditions of the encapsulation process include the drug/polymer ratio 2/1, using homogenizer for 5 min at 15000 rpm to disperse CIP in PCL solution and aqueous phase at pH 5.5. The results of CIP release study indicate that obtained microcapsules might be successfully used for designing sustained release dosage forms.

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

Secure archiving by De Gruyter and the independent archiving service Portico

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

Volume 2013 Issue 1

Issue of e-Polymers

Modulation of the electrochemical properties of SBS-based anionic membranes by the amine molecular structure

Abstract

Effect of an anionic surfactant upon the viscosity of poly(ethylene glycol) in dilute solution

Abstract

Synthesis, characterization, and drug delivery property of 2-N-carboxymethyl-6-O-diethylaminoethyl-chitosan

Abstract

Molecular dynamics simulations on dextran hydrogels

Abstract

Evaluation of poly(methyl methacrylate) latex nanoparticles used in water-based drilling fluids

Abstract

A numerical study on deformation of Newtonian droplets through converging cylindrical dies

Abstract

Conductive regenerated silk fibroin composite fiber containing MWNTs

Abstract

Application of high-resolution transmission electron microscopy and electron energy-loss spectroscopy in the characterization of polymer nanotubes

Abstract

Synthesis of binary-patterned brushes by combining atom transfer radical polymerization and ring-opening polymerization

Abstract

Effect of the boron presence on the properties of polyurethane foams obtained with hydroxypropyl derivatives of oxamide as the polyol components

Abstract

Preparation of poly(vinyl alcohol)/silica nanocomposties by sol-gel method

Abstract

Synthesis and characterization of novel polysiloxane based ABA-type triblock copolymers using ATRP

Abstract

High performance of amidoxime/amine functionalized polypropylene for uranyl (VI) from aqueous solution

Abstract

Unperturbed dimensions of polymers revisited through the blob theory: the viscometric expansion factor

Abstract

Permeability characterization of hydroxypropylcellulose/ polyacrylonitrile blend membranes

Abstract

Tuning of heavy metal removal efficiency from water via micro algae/hydrogel composites

Abstract

Enantioselective analysis of naproxen using chiral molecular imprinting polymers based thin-layer chromatography

Abstract

Controlled release of Capreomycin sulfate from pH-responsive nanocapsules

Abstract

Determination of the melting enthalpy of β phase of poly(vinylidene fluoride)

Abstract

Rheological measurement of molecular weight distribution of polymers

Abstract

Electrospinning of polyvinyl butyral in different solvents

Abstract

Intrinsic viscosity of PVP polymers in extremely diluted solutions

Abstract

Condensation of α,ω-siloxane diols with aminoalkyl- (alkoxy)silanes

Abstract

Chain length distribution and kinetic characteristics of an enzymatically produced polymer

Abstract

Preparation and characterization of poly(3-hydroxybutyrate)/ Cloisite25A nanocomposites

Abstract

Hydrogen effects in the polymerization of propylene with C2 symmetric metallocene catalysts

Abstract

Preparation of syndiotactic polystyrene using novel monotitanocene with ortho-substituted phenoxy ligands

Abstract

Acicular precipitated calcium carbonate as inorganic whisker for reinforcing of polypropylene fibers

Abstract

Encapsulation of human serum albumin in submicrometer magnetic poly(lactide-co-glycolide) particles as a model system for targeted drug delivery

Abstract

Preparation of ciprofloxacin-encapsulated poly-ε- caprolactone microcapsules by the solvent evaporation technique

Abstract

Hydrogen effects in the polymerization of propylene with C₂ symmetric metallocene catalysts