One‐pot synthesis of isocyanate and methacrylate multifunctionalized polyisobutylene and polyisobutylene‐based amphiphilic networks

Abstract

AbstractAmphiphilic polymer networks consisting of hydrophilic poly(2‐hydroxyethyl methacrylate) (PHEMA) and hydrophobic polyisobutylene (PIB) chains were synthesized from a cationic copolymer of isobutylene (IB) and 3‐isopropenyl‐α,α‐dimethylbenzyl isocyanate (IDI) prepared at −50 °C in dichloromethane in conjunction with SnCl4. The isocyanate groups of this random copolymer, PIB(NCO)n, were subsequently transformed in situ to methacrylate (MA) groups in the dibutyltin dilaurate‐catalyzed reaction with 2‐hydroxyethyl methacrylate (HEMA) at 30 °C. The resulting PIB(MA)n with number–average molecular weight 8200 and average functionality Fn ∼ 4 per chain was in situ copolymerized radically with HEMA at 70 °C, giving rise to the amphiphilic networks containing 41 and 67 mol % HEMA. PHEMA–PIB network containing 43 mol % HEMA was also prepared by radical copolymerization of PIB(MA)n precursor with HEMA using sequential synthesis. An amphiphilic nature of the resulting networks was proved by swelling in both water and n‐heptane. PIB(NCO)n and PIB(MA)n were characterized by FTIR spectroscopy, SEC and the latter also by 1H NMR spectroscopy. Solid state 13C NMR spectroscopy was used for characterization of the resulting PHEMA–PIB networks. Whereas single glass‐transition temperature, Tg = −67.4 °C, was observed for the rubbery crosslinked PIB prepared by reaction of PIB(NCO)n with water, the PHEMA–PIB networks containing 67 and 41 mol % HEMA showed two Tg's: −70.4 and 102.7 °C, and −63 and 107.2 °C, respectively. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2891–2900, 2006