Indexed by:Journal Article

Date of Publication:2015-02-09

Journal:ANGEWANDTE CHEMIE-INTERNATIONAL EDITION

Included Journals:Scopus、PubMed、EI、SCIE

Volume:54

Issue:7

Page Number:2241-2244

ISSN:1433-7851

Key Words:carbon dioxide; crystalline; enantiopure polycarbonates; epoxides; polymer stereocomplexes

Abstract:Four novel crystalline stereocomplexed polymers are formed by mixing isotactic (R)- and (S)-polycarbonates in 1:1 mass ratio. They show the enhanced thermal stability and new crystalline behavior, significantly distinct from the component enantiomer. Two stereocomplexed CO2-based polycarbonates from meso-3,4-epoxytetrahydrofuran and 4,4-dimethyl-3,5,8-trioxabicyclo[5.1.0]octane have high melting temperatures of up to 300 degrees C, about 30 degrees C higher than the individual enantiomers. Isotactic (R)- or (S)-poly(cyclopentene carbonate) and poly(cis-2,3-butene carbonate) are typical amorphous polymeric materials, however, upon mixing both enantiomers together, a strong interlocked interaction between polymer chains of opposite configuration occurs, affording the crystalline stereocomplexes with melting temperatures of about 200 degrees C and 180 degrees C, respectively. A DFT study suggests that the driving force forming the stereocomplex is the hydrogen-bonding between carbonate units of the opposite enantiomers.