Understanding Broad Polydispersity in Step-growth Polymerization via Catalyst Competition Mechanism  

作　　者：Donglai Tian Jie Wang Xiaohua Huang Yun Ding Aiguo Hu 

机构地区：[1]Shanghai Key Laboratory of Advanced Polymeric Materials,School of Materials Science and Engineering,East China University of Science and Technology Shanghai 200237,China

出　　处：《Chinese Journal of Polymer Science》2024年第12期1897-1904,I0007,共9页高分子科学（英文版）

基　　金：This work was financially supported by the National Natural Science Foundation of China(No.22171083);Shanghai Leading Academic Discipline Project(No.B502)。

摘　　要：Conjugated polymers are mainly synthesized by cross-coupling polymerizations catalyzed with transition metal(Pd,Ni)catalysts through step-growth polymerization(SGP)mechanism.According to the classical theory of SGP,the polymer dispersion index(D)of the synthesized polymers will never be higher than 2.However,the cases where conjugated polymers synthesized with D value far exceeding 2 are very common in reality,which severely limits their processing property,performance and applications.To investigate the reason behind the D value deviation from the theoretical value of SGP,direct arylation polycondensation(DArP)of 2-bromo-3-hexylthiophene(3HT)was chosen as the model reaction,and the reaction process was tracked using gel permeation chromatography analysis.When Pd(OAc)_(2) was used as the catalyst,the D value linearly increased with the increase of the weight-average molecular weight(M_(w))of polymer(P3HT)after a short period and reached up to 7.2 at prolonged reaction time.Scanning transmission electron microscopic images of the reaction mixture showed the fibril-like aggregation of P3HT and assembling of Pd species in P3HT aggregates.A catalyst competition mechanism was thus proposed,together with numerical calculation,giving a good fitting to the experimental results,which is believed to have far-reaching significance for guiding the design,synthesis and processing of conjugated polymers.

关 键 词：Step-growth polymerization Conjugated polymer Polymer dispersion index Catalyst competition mechanism 

分 类 号：O631.5[理学—高分子化学] O643.36[理学—化学]