Cationic polymerization of isobutyl vinyl ether coinitiated with heteropolyacid or its salts in aqueous medium

Abstract

The suspension cationic polymerization of isobutyl vinyl ether (IBVE) in aqueous medium could be achieved by using H₃PW₁₂O₄₀, AlPW₁₂O₄₀, FePW₁₂O₄₀, K₃PW₁₂O₄₀, or Na₃PW₁₂O₄₀ as efficient water-tolerant coinitiators in the presence of HCl. The addition reaction of IBVE with H₂O occurred to form IBVE–H₂O adduct and then subsequent decomposition immediately took place or turned to acetaldehyde diisobutyl acetal (A) in the presence of AlPW₁₂O₄₀, and (A) decomposed rapidly to form 2-isobutanol (B) and acetaldehyde (C). Cationic polymerization of IBVE in aqueous medium was promoted greatly with increasing HCl concentration and proceeded extremely rapidly to get high polymer yield even at low concentration of AlPW₁₂O₄₀ of 0.3 mM. A sufficient amount of HCl was needed to decrease the hydrolysis of initiator IBVE–HCl and to accelerate the polymerization in aqueous medium simultaneously. The yield and molecular weight of poly(IBVE) increased with increasing concentrations of HCl and AlPW₁₂O₄₀ or with decreasing temperature. The isotactic-rich poly(IBVE)s with m diad of around 60%, having M_n of 1200–4500 g mol⁻¹ and monomodal molecular weight distribution could be obtained via cationic polymerization of IBVE in aqueous medium. This is the first example of cationic polymerization of IBVE in aqueous medium coinitiated by heteropolyacid and its salts. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013