POLYSTYRENE-B-POLYDIMETHYL SILOXANE (PDMS) MULTICOMPONENT POLYMER NETWORKS - STYRENE POLYMERIZATION WITH MACROMONOMERIC INITIATORS (MACROINIMERS) HAVING PDMS UNITS

A new macromonomeric initiator (macroinimer) was synthesized and evalu ated for the bulk polymerization of styrene at 60 and 80 degrees C. Th e macroinimer containing poly(dimethylsiloxane), PDMS, was synthesized via condensation reactions between 4,-4'-azobis-4-cyanopentanoyl chlo ride (ACPC), PDMS and methacryloyl chloride. The product (MIM I) was t hermally homopolymerized and copolymerized with styrene in bulk. Kinet ics of radical polymerization of styrene with MIM I at 60 degrees C an d at low conversion was studied. Rate constant K, k(p)(fk(d)/k(1))(1/2 ), was estimated from kinetic data as 1.15 x 10(-4) 1(1/2) mol(-1/2) s . Bulk polymerization of styrene with macroinimers at 80 degrees C gav e crosslinked block copolymers. D.s.c. measurements showed that crossl inked block copolymers had a glass transition temperature around 45 de grees C. This is evidence of a plasticizing effect of flexible polysil oxane segments in copolymers. Crosslinked PDMS-b-PS block copolymers o btained using macroinimers may be an interesting group of thermoplasti c elastomers. (C) 1997 Elsevier Science Ltd.