Thermal crosslinking of poly(methyl methacrylate) by reaction of methyl ester and quaternary ammonium salt and application to (meth)acrylate-based TPEs

Copolymers of N-vinylbenzyl N-methyl pyrrolidinium chloride (VBMPC) and met hyl methacrylate, PVBMPC-co-poly(methyl methacrylate) (PMMA), were synthesi zed by free-radical copolymerization and proved to be prone to crosslinking as a result of the reaction of methyl ester groups with benzyl methyl pyrr olidinium chloride (BMPC) moieties at temperatures higher than 110 degrees C. When the VBMPC content was lower than 20 wt %, these copolymers were mis cible with homo-PMMA. Blends of homo-PMMA and PVBMPC-co-PMMA fully could be cured above 150 degrees C, when the molecular weight of PMMA exceeded 10,0 00 and the VBMPC content of the copolymer was higher than 5 wt %. This reac tion was carried out to crosslink selectively the PMMA microdomains of PMMA -b-poly(isooctyl acrylate) (PIOA)-b-PMMA (MIM) triblock copolymers to expla in the mechanism for the mechanical failure of fully (meth)acrylic thermopl astic elastomers. Comparison of the ultimate tensile properties of MIM bloc k copolymers, when the dispersed PMMA phases and PIOA matrix were crosslink ed, led to the conclusion that the ductile failure of the hard PMMA microdo mains rather than the elastic failure of the PIOA matrix was the reason for the mechanical failure of MIM triblocks. (C) 1999 John Wiley & Sons, Inc.