Synthesis of random copolymer of isobutylene with p-methylstyrene by cationic polymerization in ionic liquids

Abstract

Poly(isobutylene-co-p-methylstyrene) (IB/p-MeSt) random copolymer is a new generation of polyisobutylene-based elastomer. The cationic copolymerization of IB with p-MeSt was thoroughly examined by using various initiating systems in [Hmim][NTf2] at-30°C. The effects of initiating systems and monomer feed ratio on the monomer conversion, molecular weight and copolymer composition are discussed. The polymers were characterized by 1H-nuclear magnetic resonance (NMR), Fourier transform infrared (FTIR) spectroscopy and matrix-assisted laser desorption/ionization-time-of-flight-mass spectroscopy (MALDI-TOF-MS) to determine their chemical composition and molecular structure. The results show that high polarity, high viscosity and ionic environment of ionic liquids (ILs) influenced the copolymerization. The corresponding mechanism of cationic copolymerization in ILs is also proposed.