Star polymer synthesis using trithiocarbonate functional β‐cyclodextrin cores (reversible addition–fragmentation chain‐transfer polymerization)

Abstract

Polystyrene stars were synthesized with reversible addition–fragmentation chain‐transfer (RAFT) polymerization. The core of the stars comprised a trithiocarbonate heptafunctional β‐cyclodextrin ring. Polymerizations were performed at 100 and 120 °C in the absence of an extraneous initiator and at 60 °C in the presence of a radical initiator. Monofunctional trithiocarbonate was also synthesized and used to make linear polystyrene to allow direct a comparison with the star synthesis. In all cases, the polymerization kinetics conformed to pseudo‐first‐order behavior. The measured molecular weights of the stars were found to deviate from those predicted on the basis of the monomer/trithiocarbonate group ratio. The extent of this deviation was dependent on the polymerization temperature, RAFT agent concentration, and conversion. Despite the low radical concentrations, termination reactions are suggested to play a significant role in the seven‐arm polystyrene star syntheses. The synthetic method was found to be suitable for generating star block structures. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 4498–4512, 2002