Synthesis of hybrid dendritic-linear block copolymers with dendritic initiators prepared by convergent living anionic polymerization

Hybrid dendritic-linear block copolymers were made in one-pot by convergent living anionic polymerization. Dendritic polystyrene macroinitiators were synthesized by slowly adding a mixture of either vinylbenzyl chloride (VBC) or 4-(chlorodimethylsilyl)styrene (CDMSS) and styrene (1 : 10 molar ratio of coupling agent to styrene) to a solution of living polystyryllithium. Th e addition was ceased prior to the addition of a stoichiometric amount of c oupling agent to retain a living chain end. To the living dendritically bra nched polystyrene was then added either styrene or isoprene to polymerize a linear block from the dendritic polystyrene. The resulting copolymers were characterized by gel permeation chromatography coupled with multiangle las er light scattering (GPC-MALLS), which clearly demonstrated the formation o f diblock copolymers, The diblock copolymers were further characterized by H-1 NMR, which showed the presence of the two blocks in the case of dendrit ic polystyrene-block-linear polyisoprene. The measurement of intrinsic visc osity showed that the dilute solution properties of the block copolymers ar e greatly influenced by the dendritic portion. (C) 2000 John Wiley & Sons, Inc.