Controlled polymerization of methacrylates at ambient temperature using trithiocarbonate chain transfer agents via SET-RAFT–cyclohexyl methacrylate: A model study

Abstract

Controlled radical polymerization of cyclohexyl methacrylate (CHMA), at ambient temperature, using various chain transfer agents (CTAs) is successfully demonstrated via single electron transfer-radical addition fragmentation chain transfer (SET-RAFT). Well-controlled polymerization with narrow molecular weight distribution (M_w/M_n) < 1.25 was achieved. The polymerization rate followed first-order kinetics with respect to monomer conversion, and the molecular weight of the polymer increased linearly up to high conversion. A novel, fluorescein-based initiator, a novel fluorescent CTA and two other CTAs comprising of butane thiol trithiocarbonate with cyano (CTA 1) and carboxylic acid (CTA 3) as the end group were synthesized and characterized. The polymerization is observed to be uncontrolled under SET and less controlled under atom transfer radical polymerization (ATRP) condition. CTA 2 and 3 produces better control in propagation compared with CTA 1, which may be attributed to the presence of R group that undergoes ready fragmentation to radicals, at ambient temperature. The poly(cyclohexyl methacrylate) [P(CHMA)] prepared through ATRP have higher fluorescence intensity compared with those from SET-RAFT, which may be attributed to the quenching of fluorescence by the trithiocarbonate and the long hydrocarbon chain. It is observed that block copolymers P(CHMA-b-t-BMA) produced from P(CHMA) macroinitiators synthesized via SET-RAFT result in lower polydispersity index in comparison with those synthesized via ATRP. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010