BLOCK-GRAFT COPOLYMERS ON THE BASIS OF A STYRENE-BUTADIENE DIBLOCK COPOLYMER

Grafting from the diblock copolymers alpha b beta leads to block-graft copolymers of the form alpha b beta g gamma, the chemistry and archit ecture of which can be varied over wide limits. A family of compatibil izers for polymer blends can be prepared from one anionically produced and thus expensive copolymer, by a radically initiated grafting proce ss, which is a comparatively cheap method. When alpha b beta is asymme tric, with the block b beta carrying the graft g gamma being short, th e resulting copolymer alpha b beta/g gamma is essentially a diblock co polymer alpha b gamma. The preparation of the block-graft copolymers S bBgX, where X is methyl methacrylate (MMA) or cyclohexyl methacrylate (CHMA) is discussed. These are based on a diblock copolymer SbB of sty rene and butadiene and are grafted with MMA or CMMA. These copolymers compatibilize blends of polystyrene (PS) (or poly(phenylene ether) and poly(vinyl chloride) (PVC) (or styrene-acrylonitile (SAN) copolymer). Attention is focused on the reaction kinetics as monitored by convent ional methods and by transmission electron microscopy. The microscopic analysis shows the ongoing progress of the grafting reaction as well as the mutual miscibility of all polymers in the system. Copyright (C) 1996 Elsevier Science Ltd.