The influence of ester groups on the stereocomplex formation between different polyalkylmethacrylates

Isotactic poly(ethyl methacrylate) (it-PEMA) and syndiotactic poly(isobutyl-methacrylate) (st-PiBMA) were synthesized to investigate the stereocomplex formation with syndiotactic and isotactic poly(methyl methacrylate) (st- and it-PMMA) respectively. A d.s.c. study pointed out that it-PEMA and st-PMMA form incompatible mixtures whereas st-PiBMA and it-PMMA form compatible mixtures in which stereocomplex formation can occur as indicated by viscometry and X-ray diffraction. These results confirm the idea that the methyl ester groups of the isotactic chain and the α-methyl groups of the syndiotactic chain are responsible for stereocomplex formation.