Depletion effect on partial organization of atactic polymer chain segments in microcells
Department of Polymer Science and
Engineering, Chemistry Building, Nanjing University, Nanjing 210093, PRC
2 The State Key Laboratory of Polymer Physics and Chemistry at Changchun, Changchun 130022, PRC
Published online: 11 June 2003
Glass transition for atactic poly(methyl methacrylate) (a-PMMA) prepared in nano-cells by microemulsion polymerization was measured at a faster heating rate after slow cooling of the sample from a temperature above T g. An additional enthalpy relaxation and glass transition were observed at higher temperatures for the a-PMMA sample due to the partial organization of the chain segments which occurred during microemulsion polymerization. The re-precipitated a-PMMA did not show any self-organization under the same thermal conditions, although there are no changes in molecular weight or tacticity of the polymer chains. A depletion-interaction phenomenon was understood to provide entropic force for the self-organization of polymer chains inside the walls of the microemulsion cells.
PACS: 64.75.+g Solubility, segregation, and mixing; phase separation – / 64.70.Pf Glass transitions – / 82.35.-x Polymers: properties; reactions; polymerization –
© EDP Sciences, Springer-Verlag, Società Italiana di Fisica, 2003