Living cationic polymerization of vinyl ethers in the presence of a strong base: Poisonous or helpful?

Abstract

A quite small dose of a poisonous species was found to induce living cationic polymerization of isobutyl vinyl ether (IBVE) in toluene at 0 °C. In the presence of a small amount of N,N-dimethylacetamide, living cationic polymerization of IBVE was achieved using SnCl4, producing a low polydispersity polymer (weight–average molecular weight/number–average molecular weight (Mw/Mn) ≤ 1.1), whereas the polymerization was terminated at its higher concentration. In addition, amine derivatives (common terminators) as stronger bases allow living polymerization when a catalytic quantity was used. On the other hand, EtAlCl2 produced polymers with comparatively broad MWDs (Mw/Mn ∼ 2), although the polymerization was slightly retarded. The systems with a strong base required much less quantity of bases than weak base systems such as ethers or esters for living polymerization. The strong base system exhibited Lewis acid preference: living polymerization proceeded only with SnCl4, TiCl4, or ZnCl2, whereas a range of Lewis acids are effective for achieving living polymerization in the conventional weak base system such as an ester and an ether. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 6746–6753, 2008