Direct synthesis of highly reactive polyisobutylenes via cationic polymerization of isobutylene co‐initiated with TiCl4 in nonpolar hydrocarbon media

Abstract

ABSTRACTLiving cationic polymerization of isobutylene (IB) with 1‐chlorine‐2,4,4‐trimethyl pentane (TMPCl)/TiCl4/isopropanol (iPrOH) or isoamylol (iAmOH) has been achieved in the presence of 2,6‐di‐tert‐butylpyridine (DtBP) at −80°C. Polyisobutylenes with nearly theoretical Mn based on TMPCl molecules and more than 90% of tert‐chlorine‐end groups could be obtained at high [TMPCl]. The β‐proton elimination from CH3 in growing chain ends increased with increasing polymerization temperature and decreasing solvent polarity. A chain‐transfer‐dominated cationic polymerization process with H2O/TiCl4/iAmOH could be achieved in n‐hexane at −30°C. The monomer conversion and content of exo‐olefin end groups increased while molecular weight decreased with increasing [iAmOH]. To the best of our knowledge, this is the first example to achieve the direct synthesis of highly reactive polyisobutylene with low Mn of 1200∼1600, carrying more than 80% of exo‐olefin terminals by a single‐step process via cationic polymerization co‐initiated by TiCl4 in nonpolar hydrocarbon. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42232.