Quantitative synthesis of star-shaped poly(vinyl ether)s with a narrow molecular weight distribution by living cationic polymerization

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 ( DPn = 50-300) of isobutyl vinyl ether ( IBVE), prepared with a cationogen/EtAlCl2 at 0 degrees 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 x 10(4) to 30 x 10(4) 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.