Star‐shaped cyclopolymers: A new category of star polymer with rigid cyclized arms prepared by controlled cationic cyclopolymerization and subsequent microgel formation of divinyl ethers |
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Authors: | Tamotsu Hashimoto Haruki Matsui Michio Urushisaki Toshikazu Sakaguchi |
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Institution: | Department of Materials Science and Engineering, Graduate School of Engineering, University of Fukui, Bunkyo, Fukui, Japan |
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Abstract: | The combination of living/controlled cationic cyclopolymerization and crosslinking polymerization of bifunctional vinyl ethers (divinyl ethers) was applied to the synthesis of core‐crosslinked star‐shaped polymers with rigid cyclized arms. Cyclopolymerization of 4,4‐bis(vinyloxymethyl)cyclohexene ( 1 ), a divinyl ether with a cyclohexene group, was investigated with the hydrogen chloride/zinc chloride (HCl/ZnCl2) initiating system in toluene at 0 °C. The reaction proceeded quantitatively to give soluble poly( 1 )s in organic solvents. The content of the unreacted vinyl groups in the produced polymers was less than ~3 mol%, and therefore, the degree of cyclization of the polymers was determined to be ~97%. The number‐average molecular weight (Mn) of the polymers increased in direct proportion to monomer conversion and further increased on addition of a fresh monomer feed to the almost completely polymerized reaction mixture, indicating that living cyclopolymerization of 1 occurred. The chain linking reactions among the formed living cyclopolymers with 1,4‐bis(vinyloxy)cyclohexane ( 3 ) as a crosslinker in toluene at 0 °C produced core‐crosslinked star‐shaped cyclopoly( 1 )s star‐poly( 1 )s] in high yield (100%). Dihydroxylation of the cyclohexene double bonds of star‐poly( 1 ) gave hydrophilic water‐soluble star‐shaped polymers with rigid arm structure star‐poly( 1 )‐OH] with thermo‐responsive function in water. Tgs of star‐poly( 1 ) and star‐poly( 1 )‐OH were 135 °C and 216 °C, respectively; these values are very high as vinyl ether‐based star‐shaped polymers. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 1094–1102 |
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Keywords: | cationic polymerization cyclopolymerization living polymerization divinyl ether cyclopolymer star‐shaped polymer glass transition temperature water‐soluble polymer thermo‐responsive polymer |
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