Morphology and NMR Self-Diffusion in PBA/PEO Miktoarm Star Copolymers

Monika Makrocka-Rydzyk 1 , Katarzyna Wegner 2 , Kosma Szutkowski 3 , Maciej Kozak 4 , Stefan Jurga, Haifeng Gao 5  and Krzysztof Matyjaszewski 6
  • 1 Adam Mickiewicz University, Department of Macromolecular Physics, Poznán, Polen
  • 2 Adam Mickiewicz University, NanoBioMedical Centre, Poznán, Polen
  • 3 Adam Mickiewicz University, Department of Macromolecular Physics, Poznán, Polen
  • 4 Adam Mickiewicz University, Department of Macromolecular Physics, Poznán, Polen
  • 5 Carnegie Mellon University, Department of Chemistry, Pittsburgh, Pennsylvania, U.S.A.
  • 6 Carnegie Mellon University, Department of Chemistry, Pittsburgh, Pennsilvania, U.S.A.

Abstract

Morphology and NMR self-diffusion of two miktoarm star copolymers differing in fraction of poly(n-butyl acrylate) and poly(ethylene oxide) (PBA and PEO) arms were under investigation. Structural characteristics of copolymers was obtained on the basis of Small Angle X-Ray Scattering (SAXS) investigations. The phase separated nanoscale morphology of the miktoarm star copolymer with a high fraction of PEO arms was confirmed by Scanning Probe Microscopy (SPM) studies. The modified Avrami approach was used to obtain the information on the non-isothermal crystallization kinetics of the studied systems. It was observed that the crystallization in the system with a higher content of PBA, occurring at higher undercooling, was characterized by a higher crystallization rate. It was also found that increase in PBA arms fraction leads to the reduction in the size of PEO domains. The activation energy of the crystallization process, estimated with Kissinger's method, is lower for miktoarm star copolymer with higher PBA content, which results from facilitation of the transport of PEO chains in the direction of the growing crystal due to the presence of mobile PBA arms. The self-diffusion studies of miktoarm star copolymers melts, carried out with the Pulsed-Gradient STimulated-Echo (PGSTE) Nuclear Magnetic Resonance (NMR) technique, reveals the existence of at least two types of diffusion mechanisms in these systems.

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Founded in 1887, the Zeitschrift für Physikalische Chemie covers the main developments in physical chemistry, placing with an emphasis on experimental research. It represents a combination ofdiscusses reaction kinetics and spectroscopy, surface research and electrochemistry, thermodynamics and the structure analysis of matter in its various conditions, among other topics.

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