Stereoregular CO2 Copolymers from Epoxides with an Electron-Withdrawing Group: Crystallization and Unexpected Stereocomplexation
发表时间：2019-03-11
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- 论文类型：
- 期刊论文
- 第一作者：
- Ren, Wei-Min
- 通讯作者：
- Ren, WM; Lu, XB (reprint author), Dalian Univ Technol, State Key Lab Fine Chem, 2 Linggong Rd, Dalian 116024, Peoples R China.
- 合写作者：
- Yue, Tian-Jun,Zhang, Xue,Gu, Ge-Ge,Liu, Ye,Lu, Xiao-Bing
- 发表时间：
- 2017-09-26
- 发表刊物：
- MACROMOLECULES
- 收录刊物：
- Scopus、SCIE、EI
- 文献类型：
- J
- 卷号：
- 50
- 期号：
- 18
- 页面范围：
- 7062-7069
- ISSN号：
- 0024-9297
- 摘要：
- Highly regioselective copolymerization of CO2 and enantiopure terminal epoxides with an electron-withdrawing group, styrene oxide and its derivatives, was achieved by the use of multichiral salenCo(III) complex-based catalyst systems, in which epoxide ring-opening predominantly occurred at methylene C-O bond, affording isotactic CO2 copolymers with up to 98% head-to-tail connectivity and 97% enantioselectivity. The stereoregular polystyrene carbonate) with 98% isotacticity is a typical semicrystalline material, possessing a melting temperature (T-m) of 137.3 degrees C and an enhanced glass transition temperature (T-g) of 101.2 degrees C. The isotactic 3-methoxystyrene oxide/CO2 copolymer is also a semicrystalline polymer with a T-m of around 90 degrees C, while the corresponding isotactic 3-chlorostyrene oxide/CO2 copolymer appears amorphous feature, possessing a T-g of 82.1 degrees C. Notably, a novel stereoselective interaction between two opposite-configuration isotactic polymers was first found in the blend of equivalent (R)- and (S)-polycarbonates from terminal epoxides. The strong interlocked interaction between isotactic (R)- and (S)-poly(styrene carbonate)s affords the crystalline stereocomplexes with a T-m of 164.1 degrees C, about 27 degrees C higher than that of the enantiopure isotactic polymers. Surprisingly, isotactic (R)- or (S)-3-chlorostyrene oxide/CO2 copolymer is typical amorphous polymeric material; however, upon mixing both enantiomers together, an interlocked interaction between polymer chains of opposite configuration occurs, affording the crystalline stereocomplexes with a T-m of 147.3 degrees C.
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- 否
