Dielectric and molecular dynamics study of the secondary relaxations of poly(styrene-co-methylmethacrylate) copolymers: Influence of the molecular architecture.
作者： M. Encinar , M. G. Prolongo , R. G. Rubio , F. Ortega , A. Ahmadi
DOI: 10.1140/EPJE/I2011-11134-4
关键词: Methyl methacrylate 、 Methacrylate 、 Styrene 、 Molecular dynamics 、 Arrhenius equation 、 Crystallography 、 Materials science 、 Copolymer 、 Activation energy 、 Relaxation (NMR)
摘要: The effect of the structure copolymers (random, alternate or diblock) on their dynamics has been studied by dielectric spectroscopy. Six styrene and methyl methacrylate (three diblocks, one two random) have studied. results show that sub- Tg transitions diblock samples can be described asymmetric Havriliak-Negami (HN) function, while are necessary for rest (β γ relaxations). characteristic times relaxations an Arrhenius temperature dependence there is a strong coupling α β at high temperatures. deconvolution merging made in framework Williams Ansatz set out terms distributions. Because 2D 2H-NMR excluded any significant contribution from rotation methoxy group around C-OCH3 bond, relaxation may assigned to styrene-rich environment. Molecular Dynamics simulations poly(methyl methacrylate) homopolymer copolymer qualitative agreement with experimental results, although they predict smaller values activation energy relaxations.
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