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Indexed by:Journal Papers

Date of Publication:2019-10-08

Journal:Angewandte Chemie (International ed. in English)

Included Journals:PubMed

ISSN No.:1521-3773

Key Words:copolymerization,crystallinity,isomerization,smart materials,unsaturated polyesters

Abstract:An aliphatic polyester has been prepared from ethylene oxide and maleic anhydride that undergoes reversible transformation between amorphous (Tg =18 °C) and crystalline (Tm =124 °C) states through cis-trans isomerization of the C=C bonds in the polymer backbone without any change in either the molecular weight or dispersity of the polymer. A similar transformation was also observed in chiral unsaturated polyesters formed from enantiopure terminal epoxides, such as epichlorohydrin, phenyl glycidyl ether, and (2,3-epoxypropyl)benzene. These unsaturated polyesters with 100 % E-configuration in the crystalline state were prepared by quantitative isomerization of their Z-configuration analogues in the presence of a catalytic amount of diethylamine, while in the presence of benzophenone, irradiation with 365 nm UV light resulted in the transformation of about 30 % trans-alkene to cis-maleate form, thereby affording amorphous polyesters.© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.