Synthesis of Poly(cyclohexyl vinyl ether-b-isobutylene-b-cyclohexyl vinyl ether) Triblock Copolymer by Living Cationic Sequential Copolymerization
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- Zhou, Y. & Faust, R. Polym. Bull. (2004) 52: 421. doi:10.1007/s00289-004-0306-9
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The living cationic polymerization of cyclohexyl vinyl ether (CHVE) and sequential block copolymerization of isobutylene with CHVE were carried out by the so-called capping-tuning technique in hexanes/CH3Cl solvent mixtures at –80 °C. It involves capping the initiator, 2-chloro-2,4,4-trimethylpentane (TMPCl), or the living polyisobutylene (PIB) chain end with 1,1-ditolylethylene in the presence of titanium(IV) (TiCl4), followed by fine-tuning of the Lewis acidity with the addition of titanium(IV) isopropoxide (Ti(OIp)4) to match the reactivity of CHVE. Well-defined PCHVE, PIB-b-PCHVE and PCHVE-b-PIB-b-PCHVE with predesigned molecular weights and narrow molecular weight distributions (Mw/Mn<1.1) were thus prepared with [Ti(OIp)4]/[TiCl4] ratios of 1.6–1.8. Differential scanning calorimetry of the triblock copolymers showed two Tgs (–62 °C for PIB and 61 °C for PCHVE) suggesting a microphas-separated morphology of the triblock copolymers and the potential use of them as thermoplastic elastomers.