CO2-Tuned Sequential Synthesis of Stereoblock Copolymers Comprising a Stereoregularity-Adjustable Polyester Block and an Atactic CO2-Based Polycarbonate Block,Macromolecules

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CO2-Tuned Sequential Synthesis of Stereoblock Copolymers Comprising a Stereoregularity-Adjustable Polyester Block and an Atactic CO2-Based Polycarbonate Block
Macromolecules ( IF 5.1 ) Pub Date : 2017-11-30 00:00:00 , DOI: 10.1021/acs.macromol.7b01905
Bing Han ₁ , Binyuan Liu ₁ , Huining Ding ₁ , Zhongyu Duan ₁ , Xianhong Wang ₂ , Patrick Theato ₃

Affiliation

Stereoblock copolymers composed of atactic CO₂-based polycarbonate and various stereoregular polyester blocks with cis-2,3-(exo, exo), cis-2,3-(endo, endo), or partly trans-2,3-(exo, endo) repeating units were successfully synthesized via sequential ring-opening copolymerization (ROCOP) of cyclohexene oxide (CHO) with norbornene anhydride (NA) and then ROCOP of CHO with CO₂ using a salcyCrCl/PPNCl binary catalyst. The structure of the block copolymers was confirmed by NMR and GPC. Incorporation of carboxyl groups by the thiol–ene reaction of the pendant norbornenyl groups further confirmed the polymer structures. The geometric structure of polyester units in the block copolymers is tailored simply by varying the NA isomer and the monomer feed ratio of CHO to NA. Notably, CO₂ suppressing the configuration transformation from cis-(exo, exo) to trans-(exo, endo) of polyester block has been revealed in the sequential ROCOP. Using this strategy, the stereospecific polyester with an dominant cis-2,3-(exo, exo)-poly(NA-alt-CHO) units, the thermodynamically less stable isomeric form, was obtained in the ROCOP of exo-NA with an excess of CHO in the presence of CO₂. The role of CO₂ in restraining the geometric transformation from cis-(exo, exo) to trans-(exo, endo) was proposed in the ROCOP of exo-NA with an excess of CHO catalyzed by PPNCl.

中文翻译：

包含立体规整度可调的聚酯嵌段和无规立构的基于CO ₂的聚碳酸酯嵌段的立体嵌段共聚物的CO ₂调谐顺序合成

无规立构CO组成的立构共聚物₂系聚碳酸酯和具有各种立构规整聚酯嵌段顺式2,3 - （外，外切），顺式2,3- - （内，内），或部分地反式- 2,3- - （外，内切）的重复单元分别通过氧化环己烯的顺序开环共聚（ROCOP）（CHO）与降冰片烯酸酐（NA成功合成），然后CHO的ROCOP用CO ₂使用salcyCrCl / PPNCl二元催化剂。嵌段共聚物的结构通过NMR和GPC确认。降冰片烯基侧基的硫醇-烯反应结合了羧基，进一步证实了聚合物的结构。只需通过改变NA异构体和CHO与NA的单体进料比即可简单地调整嵌段共聚物中聚酯单元的几何结构。值得注意的是，在连续式ROCOP中已经发现了CO ₂抑制了聚酯嵌段从顺式（exo，exo）向反式（exo，endo）的构型转变。使用这种策略，具有主要顺式-2,3的立体定向聚酯- （外，外切）-聚（NA- ALT -CHO）单元，热力学不太稳定的异构体形式，是在的ROCOP得到外- NA在CO存在过量的CHO的₂。CO的作用₂在抑制从几何变换的顺式- （外，外），以反式（外，内）中的ROCOP提出外型-NA与过量的CHO的催化由PPNCl。

更新日期：2017-11-30

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