The preparation and characterization of a polyisobutylene-b-poly(ε-caprolactone) (PIB-b-PCL) diblock copolymer is reported. Terminally unsaturated PIB (> 85%) was hydroxy functionalized by hydroboration followed by oxidation to give hydroxyl terminated PIB(PIB-OH). The reaction of PIB-OH with ε-caprolactone, using stannous octoate as catalyst, gave the resulting PIB-b-PCL copolymer. 1H and 13C nuclear magnetic resonance (n.m.r.) spectroscopy was used to characterize the copolymers as well as determine their composition. In each case, the degree of polymerization (DP) of poly(ε-caprolactone) as well as the PIB/PCL ratio are reported. It was found that while copolymerization data essentially agree with the theoretical values based on PIB and ε-caprolactone stoichiometry, the amount of PIB in the diblocks deviates from the expected amounts with increasing caprolactone content. 1H n.m.r. also shows that the reactivity of PIB-OH with the ε-caprolactone monomer is restricted to only those polymer chains possessing a primary hydroxyl chain end since secondary hydroxyl functionality does not initiate lactone polymerization. Model studies involving the ring opening of ε-caprolactone by primary and secondary alcohols also support this finding.
|Original language||English (US)|
|Number of pages||4|
|Journal||Polymer communications Guildford|
|State||Published - Jul 1 1990|
All Science Journal Classification (ASJC) codes