Polyesters with cyclic structures in the main chain typically possess superior mechanical and thermal properties together with chemical recyclability.Ring-opening polymerization(ROP)of bridged or fused bicyclic lactones is a simple,and in most cases controlled method to synthesize polyesters with alicyclic moieties in the polymer backbone.The stereochemistry of the alicyclic structures has a great effect on the polymer properties,which can be regulated by varying the polymerization conditions.Here,we report a systematic investigation on the ROP of 2-oxabicyclo[2.2.2]octan-3-one([2.2.2]VL)under different conditions.When initiated by n-butyl lithium(n-BuLi)or catalyzed by trifluoromethanesulfonic acid(TfOH)in the presence of benzyl alcohol,P[2.2.2]VLs containing all cis-1,4 disubstituted cyclohexane ring were obtained.However,P[2.2.2]VLs initiated by sodium methoxide(MeONa)or catalyzed by organic superbase contained both cis and trans isomeric structural units.The cis to trans transformation mechanism under these conditions was manifested,and the effect of stereochemical variations on the properties of P[2.2.2]VL was revealed.The stereoregular P[2.2.2]VLs,both cis and trans,exhibited higher crystallinity and melting temperatures(Tm)than those of the stereoirregular isomers.Finally,the degradation of P[2.2.2]VL with acid at high temperature could recover 3-cyclohexenecarboxylic acid.

Tong Zhou;Yu-Ting Guo;Fu-Sheng Du;Zi-Chen Li

Beijing National Laboratory for Molecular Sciences(BNLMS),Key Laboratory of Polym.Chem.&Physics of Ministry of Education,Department of Polymer Science&Engineering,College of Chemistry and Molecular Engineering,Center for Soft Matter Science and Engineering,Peking University,Beijing 100871,China

高分子科学（英文版）

[1]Tong Zhou;Yu-Ting Guo;Fu-Sheng Du;Zi-Chen Li-.Ring-opening Polymerization of 2-Oxabicyclo[2.2.2]octan-3-one and the Influence of Stereochemistry on the Thermal Properties of the Polyesters)[J].高分子科学（英文版）,2022(10):1173-1182

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