| Abstract: | Statistical copolymers of styrene and ortho-vinylbenzaldehyde (o-VBA) have been prepared by free radical solution polymerization using azodiisobutyronitrile initiator. Subsequent “grafting from” reactions could be induced through photolytic excitation of the pendant aldehyde carbonyl functionality in the presence of methyl methacrylate monomer; however, actual grafting of polymethylmethacrylate (PMMA) to the copolymer backbone was shown to be quite low (< 6% graft-on). Another more promising route involved abstraction of labile benzylic hydrogens of the copolymer by chemical methods [e.g., dibenzoyl peroxide or α,α′-di-(t-butylperoxy)diisopropylbenzene] to produce potential graft sites. Graft copolymers prepared by this procedure had PMMA content ranging up to about 30% (by weight), depending upon polymerization conditions. Higher grafting levels were generally observed with increasing reaction temperature and prolonged reaction times. While some grafting evidently originated from the copolymer backbone, the presence of the o-VBA moiety significantly enhanced the ultimate percent grafting. The resulting multicomponent polymer systems displayed substantial miscibility as evidenced by the transparency of their cast films as well as by their glass transition behavior. |
