From NMP to RAFT and thiol-ene chemistry by in situ functionalization of nitroxide chain ends

Abstract

A straightforward, novel strategy based on the in situ functionalization of polymers prepared by nitroxide-mediated polymerization (NMP), for the use as an extension toward block copolymers and post-polymerization modifications, has been investigated. The nitroxide end group is exchanged for a thiocarbonylthio end group by a rapid transfer reaction with bis(thiobenzoyl) disulfide to generate in situ reversible addition-fragmentation chain transfer (RAFT) macroinitiators. Moreover, not only have these macroinitiators been used in chain extension and block copolymerization experiments by the RAFT process but also a thiol-terminated polymer is synthesized by aminolysis of the RAFT end group and subsequently reacted with dodecyl vinyl ether by thiol-ene chemistry. A strategy based on the controlled addition of a disulfide during NMP is investigated for the synthesis of macro-CTA's. These compounds are subsequently used to obtain block copolymers by RAFT polymerization and also reduced to thiols for further functionalization of the polymer chain-ends by thiol-ene chemistry.