Indexed by:期刊论文

Date of Publication:2018-03-01

Journal:JOURNAL OF ENERGY CHEMISTRY

Included Journals:SCIE、EI

Volume:27

Issue:2

Page Number:361-366

ISSN No.:2095-4956

Key Words:Stereocomplexed polycarbonates; Crystalline carbonate polymers; Stacking interaction; Solid-state NMR; DFT

Abstract:CO2-based stereocomplexed polycarbonates derived from the intermolecularly interlocked interaction between the enantiopure polymers with the opposite configuration exhibit high crystallinity, excellent thermal and mechanical stabilities. Deep insights into the mechanism of stereocomplexation are of particular importance to the design and manufacture of new promising and sustainable polycarbonates with enhanced physicochemical properties. Our solid-state NMR experiments linking with DFT computations clearly reveal the specific chain-chain interactions in a typical stereocomplexed poly (4,4-dimethyl3,5,8-trioxabicyclo[5.1.0] octane carbonate) (PCXC). C-13 CP/MAS NMR, H-1 DUMBO MAS NMR and C-13/H-1 relaxation-time measurements indicate that the formation of stereocomplex reduces the local mobilities of carbonyl, methine and methylene groups in each chain of PCXC significantly. Through a combination of two-dimensional H-1-C-13 HETCOR NMR and DFT calculation analysis, the cis-/trans-conformations and packing models of PCXC chains in the amorphous, enantionpure isotactic and stereocomplexed polycarbonates are identified. The splitting of C-13 and H-1 NMR chemical shifts of methine groups in the backbone carbon region demonstrates the ordered interlock interactions between the R- and S-chain in the stereocomplexed PCXC. (C) 2018 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. and Science Press. All rights reserved.