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Highly reactive polyisobutylenes via AlCl3OBu2-coinitiated cationic polymerization of isobutylene: Effect of solvent polarity, temperature, and initiator

Authors

  • Irina V. Vasilenko,

    1. Research Institute for Physical Chemical Problems of the Belarusian State University, 14 Leningradskaya St., 220030 Minsk, Belarus
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  • Dmitriy I. Shiman,

    1. Research Institute for Physical Chemical Problems of the Belarusian State University, 14 Leningradskaya St., 220030 Minsk, Belarus
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  • Sergei V. Kostjuk

    Corresponding author
    1. Research Institute for Physical Chemical Problems of the Belarusian State University, 14 Leningradskaya St., 220030 Minsk, Belarus
    • Research Institute for Physical Chemical Problems of the Belarusian State University, 14 Leningradskaya St., 220030 Minsk, Belarus
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Abstract

The cationic polymerization of isobutylene using 2-phenyl-2-propanol (CumOH)/AlCl3OBu2 and H2O/AlCl3OBu2 initiating systems in nonpolar solvents (toluene, n-hexane) at elevated temperatures (−20 to 30 °C) is reported. With CumOH/AlCl3OBu2 initiating system, the reaction proceeded by controlled initiation via CumOH, followed by β-H abstraction and then irreversible termination, thus, affording polymers (Mn = 1000–2000 g mol−1) with high content of vinylidene end groups (85–91%), although the monomer conversion was low (≤35%) and polymers exhibited relatively broad molecular weight distribution (MWD; Mw/Mn = 2.3–3.5). H2O/AlCl3OBu2 initiating system induced chain-transfer dominated cationic polymerization of isobutylene via a selective β-H abstraction by free base (Bu2O). Under these conditions, polymers with very high content of desired exo-olefin terminal groups (89–94%) in high yield (>85%) were obtained in 10 min. It was shown that the molecular weight of polyisobutylenes obtained with H2O/AlCl3OBu2 initiating system could be easily controlled in a range 1000–10,000 g mol−1 by changing the reaction temperature from −40 to 30 °C. The MWD was rather broad (Mw/Mn = 2.5–3.5) at low reaction temperatures (from −40 to 10 °C), but became narrower (Mw/Mn ≤ 2.1) at temperatures higher than 10 °C. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012

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