ABSTRACT
Graft copolymers have been synthesized from the grafting vinyl monomer copolymerization onto polymers by radical, anionic, and cationic initiation processing. In general, there are three ways for synthesis of graft copolymers by radical initiation reaction: ( 1) chain-transfer reaction; (2) redox initiation with eerie salt, Ce(IV) ion, and photo-induced charge-transfer reaction; and (3) copolymerization of vinyl monomer with macromer [I ,2). However, these methods yield a mixture of homopolymer, graft copolymer, and ungrafted original polymer. Some systems such as high-impact polystyrene (HIPS), acrylonitrile-butadiene-styrene (ABS) polymer, and methyl methacrylate-butadiene-styrene (MBS) polymers have been commercialized. For characterization, the purification of graft copolymer is necessary and even the purification process is tedious. Furthermore, the free radical grafting reactions of polymers can proceed either along the main chain (backbone) of the polymer or from the pendant groups (side chain), these make it difficult to realize the grafting site in a graft copolymer. In our laboratory on the basis of investigation of vinyl radical polymerization initiation systems [3-7), i.e., Ce(IV) ion redox and amine-benzophenone photo-induced chargetransfer initiation systems, we have developed some techniques for graft copolymerization via initiation reaction of active pendant groups of polymers either by redox or photo-induced charge-transfer reaction. Theresults of our research work concerning the model compounds of active functional group for Ce(IV) ion redox
initiation systems and their initiation mechanism; the synthesis of macromolecules having active pendant group and its grafting reaction; and the grafting mechanism as well as the grafting site are reviewed in this chapter.
