TETRAPHENYLETHANE INIFERTERS - 9 - DIPHENYLMETHANE DIISOCYANATE-BASEDPOLYURETHANE-POLYSTYRENE BLOCK-COPOLYMERS THROUGH LIVING RADICAL MECHANISM

4,4'-Diphenylmethane diisocyanate-based polyurethane iniferters contai ning tetraphenylethane groups in between polyurethane blocks have been prepared by reacting isocyanate terminated prepolymers and 1,1,2,2-te traphenyl-1,2-ethanediol. Polymerization of styrene using these inifer ters yielded polyurethane-polystyrene block copolymers through a ''liv ing'' radical mechanism. The effect of changing polyol on T-g, thermal stability and molecular weight of polyurethane iniferters as well as block copolymers have been studied. The molecular weight of the block copolymers increased with increasing both polymerization time and conv ersion thereby proving ''living'' radical mechanism. (C) 1997 Elsevier Science Ltd.