Quantitative Synthesis of Star-Shaped Poly(vinyl ether)s with a Narrow Molecular Weight Distribution by Living Cationic Polymerization

• Published in: Journal of the American Chemical Society Vol. 128; no. 23; pp. 7497 - 7504
• Main Authors: Shibata, Takaho, Kanaoka, Shokyoku, Aoshima, Sadahito
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 14.06.2006
• Subjects: Applied sciences; Exact sciences and technology; Organic polymers; Physicochemistry of polymers; Polymerization; Preparation, kinetics, thermodynamics, mechanism and catalysts; Thermal properties; Atomic force microscopy; Molecular weight distribution; Molecular weight determination; Optical properties; Living polymer; Star polymer; Cationic polymerization; Isobutyl vinyl ether polymer; Polymer structure; Gel permeation chromatography
• ISSN: 0002-7863; 1520-5126
• DOI: 10.1021/ja057611h

Star-shaped poly(vinyl ether)s with narrow molecular weight distributions were obtained from polymer-linking reactions of living polymers with a divinyl compound based on living cationic polymerization. For example, living polymers (DP n = 50−300) of isobutyl vinyl ether (IBVE), prepared with a cationogen/EtAlCl2 at 0 °C in hexane in the presence of ethyl acetate, were allowed to react with a small amount of 1,4-cyclohexanedimethanol divinyl ether (DVE-1) to give a star-shaped poly(IBVE) in quantitative yield (100%). In addition, a notable feature of this star-shaped polymer was extremely narrow molecular weight distribution (M w/M n = 1.1−1.2). The structure of divinyl compounds and reaction conditions for the linking reaction are key factors for achieving quantitative yield of star-shaped polymers. To our best knowledge, this is the first example of selective preparation of star-shaped polymers with narrow molecular weight distribution via one-pot polymer-linking reactions, which has never been achieved in any other mechanisms. The M w and the number of arms per molecule ranged from 6 × 104 to 30 × 104 and 9 to 44, respectively. Thermosensitive star polymers were also synthesized in quantitative yield, and the products were found to undergo sensitive phase separation and physical gelation.