Synthesis of graft copolymers by a transesterification method

Abstract

It is shown for the first time that mutual transesterification between carbochain polyesters (polymethyl methacrylate) and heterochain polyesters may be used for synthesizing graft copolymers. The graft copolymers obtained from polymethyl methacrylate and crystalline polyesters are crystalline have high softening temperatures. The grafting of amorphous polyesters yields amorphous graft copolymers. An increase in the number of graft side chains is accompanied by a decrease in intrinsic viscosity of the copolymer and by a rise in value of the Huggins constant. The decrease in the intrinsic viscosity is not the result of a degradation process, since polymethyl methacrylate may be regenerated by methanolysis of the graft copolymers. The intrinsic viscosity of the regenerated polymethyl methacrylate is equal to that of the initial polymer. Graft copolymers from polymethyl methacrylate and heterochain polyesters possess a lower tensile strength and higher ultimate elongation than polymethyl methacrylate. It was also established that on heating mixtures of methyl methacrylate and ω‐hydroxyacids in the presence of a catalyst graft copolymers form by simultaneous polymerization, polycondensation, and mutual transesterification reactions. Some correlations in this process and the properties of the resultant graft copolymers have been studied.

Direct access to functional (Meth)acrylate copolymers through transesterification with lithium alkoxides

“…To optimize and increase the efficiency of transesterification reactions a variety of suitable catalysts, ranging from organic and inorganic bases, to Lewis acids, and N ‐heterocyclic carbenes, have been developed . For polymer chemists, transesterification is a useful tool for the synthesis of polyesters, for example, poly(ethylene terephthalate) through transesterification of dimethyl terephthalate with ethylene glycol or for reactive compatibilization of polymer blends by the in‐situ formation of copolymers in the presence of transesterification catalysts …”

“…36,37 For polymer chemists, transesterification is a useful tool for the synthesis of polyesters, for example, poly (ethylene terephthalate) through transesterification of dimethyl terephthalate with ethylene glycol 37 or for reactive compatibilization of polymer blends by the in-situ formation of copolymers in the presence of transesterification catalysts. [38][39][40][41][42][43][44] Herein we report the combination of transesterification and side chain modification for the development of a robust and versatile strategy for PMMA modification. Unfortunately, previous attempts at PMMA functionalization have been problematic due to the steric hindrance surrounding the ester groups with only a limited number of examples being reported in the literature.…”