Cationic polymerization of isobutylene by complexes of alkylaluminum dichlorides with diisopropyl ether: An activating effect of water

Abstract

The RAlCl2 × OiPr2-co-initiated (R = iBu or Et) cationic polymerization of isobutylene in the presence of externally added water (0.016–0.1 mM) in nonpolar n-hexane at 10 °C and high monomer concentration ([IB] = 5.8 M) has been investigated. It was shown that the sequence of H2O introduction into the system had the crucial effect on the polymerization rate, saturated monomer conversion, and, to a lesser extent, the content of exo-olefin end groups. Particularly, the highest polymerization rate (>70% of monomer conversion in 10 min) and acceptable exo-olefin end groups content (∼83%) were observed when iBuAlCl2 × 0.8OiPr2 reacted with suspended in n-hexane H2O before the monomer addition. Better functionality can be obtained when H2O is introduced into the system in the course of the polymerization (after 3–10 min since the initiation of reaction). Under these conditions, highly reactive polyisobutylenes (exo-olefin content is 86–89%) with desired low molecular weight (Mn = 1000–2000 g mol−1) in a high yield (75–90% of monomer conversion in 20 min) were readily synthesized. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 2386–2393