Polyisobutylene RAFT CTA by a Click Chemistry Site Transformation Approach: Synthesis of Poly(isobutylene-b-N-isopropylacrylamide)

A novel block copolymer, composed of polyisobutylene (PIB) and poly(N-isopropylacrylamide) (PNIPAM) segments, was synthesized The PIB block was prepared via quasiliving cationic polymerization and end-functionalized by in-situ quenching to yield telechelic halogen-terminated PIB Azido functionality was obtained by displacement of the terminal halogen through nucleophilic substitution. which was confirmed by both H-1 and C-13 NMR Coupling of an alkyne-functional chain transfer agent (CTA) to azido PIB was successfully accomplished through a copper-catalyzed click reaction Structure of the resulting PIB-based macro-CTA was verified with H-1 NMR FTIR and GPC, whereas coupling reaction kinetics were monitored by real-time variable temperature (VT) H-1 NMR. Subsequently, the function of this macro-CTA was demonstrated by RAFT polymerization of NIPAM for synthesis of the second block RAFT kinetics was investigated under a variety of reaction conditions using VT NMR, and the resulting block copolymers were characterized by H-1 NMR and GPC Aqueous Solution properties were probed by dynamic light scattering confirming the presence of self-assembled aggregates with reversible temperature-sensitive responsiveness