Unveiling chain–chain interactions in CO2-based crystalline stereocomplexed polycarbonates by solid-state NMR spectroscopy and DFT calculations  

作　　者：Zhenchao Zhao Pengju Ren Ye Liu Kangbo Zhao Xiao-Bing Lu Weiping Zhang 

机构地区：[1]State Key Laboratory of Fine Chemicals, School of Chemical Engineering, Dalian University of Technology, Dalian 116024, Liaoning, China [2]Srate Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan 030001, Shanxi, China [3]national Energy Center for Coal to Clean Fuels, Synfuels China Co., Ltd, Huairou District, Beijing 101400, China

出　　处：《Journal of Energy Chemistry》2018年第2期361-366,共6页能源化学（英文版）

基　　金：financial supports from the National Natural Science Foundation of China (Nos. 21373035, 21673027 and 21603022);the Fundamental Research Funds for the Central Universities in China (Nos. DUT16RC(3)002 and DUT17TD04)

摘　　要：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-dimethyl-3,5,8-trioxabicyclo[5.1.0] octane carbonate）（PCXC）.13C CP/MAS NMR,1H DUMBO MAS NMR and 13C/1H 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 1H-13C 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 13C and 1H 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.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-dimethyl-3,5,8-trioxabicyclo[5.1.0] octane carbonate）（PCXC）.13C CP/MAS NMR,1H DUMBO MAS NMR and 13C/1H 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 1H-13C 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 13C and 1H 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.

关 键 词：Stereocomplexed polycarbonates Crystalline carbonate polymers Stacking interaction Solid-state NMR DFT 

分 类 号：O633.14[理学—高分子化学]