Glass temperatures of random copolymers of electron-donor and electron-acceptor monomers

Abstract

The composition dependence of the glass temperatures of copolymers containing monomeric units with electron-donor and/or electron-acceptor groups shows serious deviations from additivity. For electron-donor/electron-acceptor copolymers these deviations are more or less symmetric and, depending on the length of the spacer between the interacting groups and the methacrylic polymeric backbone, they vary from positive for the short ethyl spacer to negative for longer spacers. Glass temperatures of copolymers of methyl and n-butyl acrylates (methacrylates) with the respective electron-donor or electron-acceptor monomers always show asymmetric deviations from additivity. These deviations are mostly positive and situated on the donor-poor side for the donor copolymers and negative and situated on the acceptor-rich side for the acceptor copolymers. The deviations are more pronounced for the methacrylates and decrease from the methyl to the n-butyl ester.