Copolymerization behaviour of pentadiene-functional macromonomers obtainedby free radical addition-fragmentation

Pentadiene-functional macromonomers based on poly (methyl methacrylate) (PM MA) and polystyrene (PS). obtained through a free radical addition-fragment ation reaction were copolymerized with styrene, methyl methacrylate (MMA) a nd methacrylic acid (MAA) to synthesise well defined graft copolymers. Thus , PMMA-g-PS, PS-g-PMMA and PS-g-PMAA of varying compositions and graft leng ths were synthesised. The copolymerization kinetics revealed diminished rea ctivity of the pentadiene function of the macromonomer towards a given como nomer vis-a-vis the reactivities of the pentadiene monomer or the pentadien e function on the addition-fragmentation agent used to prepare the macromon omers. Methacrylic acid showed apparently reduced reactivity than MMA and t he copolymerization of the former with PS-based macromonomer gave amphiphil ic graft copolymers with different solubility characteristics. The reactivi ty of the terminal pentadiene-function of the macromonomer was found to be independent of its molar mass, although its reactivity was marginally dimin ished in comparison with pentadiene monomer. Low concentrations of high mol ar mass macromonomer led to the concomitant formation of homopolymers of th e small monomer in the case of copolymerization with reactive monomers like MMA and MAA. The graft copolymers have been characterized by chemical meth ods and by GPC using multiple detectors. (C) 1999 Elsevier Science Ltd. All rights reserved.