Dynamic Ring-chain Equilibrium of Nucleophilic Thiol-yne "Click" Polyaddition for Recyclable Poly(dithioacetal)s  

作　　者：Jin-Xia Lei Qi-Yuan Wang Fu-Sheng Du Zi-Chen Li 

机构地区：[1]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

出　　处：《Chinese Journal of Polymer Science》2021年第9期1146-1154,共9页高分子科学（英文版）

基　　金：This work was financially supported by the National Key Research and Development Program of China(No.2016YFA0201400);the National Natural Science Foundation of China(Nos.21971005 and 21534001).

摘　　要：We report a dynamic polymerization system based on the reversible nucleophilic Michael polyaddition of activated alkynes and dithiols.Four poly(dithioacetal)s(P1-P4)were prepared via the base-catalyzed thiol-yne"click"polyaddition of two dithiols(1,4-butanedithiol(4S)and 1,5-pentanedithiol(5S))and two alkynones(3-butyn-2-one(Y1)and 1-phenyl-2-propyn-1-one(Y2))at high concentrations.We systematically investigated the base-catalyzed polymerization of 4S and Y1(for polymer PI)under different conditions,and found that this polymerization was a highly concentration-dependent dynamic system:polymer PI was formed at high concentration,while seven-membered dithioacetal,1-(1,3-dithiepan-2-yl)propan-2-one(C1),was obtained at low concentration.The polymerization of 4S and Y2(for polymer P4)displayed similar polymerization behavior,generating 2-(1,3-dithiepan-2-yl)-1-phenylethanone(C4)at low concentration.On the contrary,polymer P2(from Y1 and 5S)was exclusively obtained with no formation of eight-membered dithioacetal.The polymerizations of Y1 with 1,2-ethanedithiol(2S)and 1,3-dimercaptopropane(3S)only afforded corresponding five-and six-membered dithioacetals,1-(1,3-dithiolan-2-yl)propan-2-one(C2)and 1-(1,3-dithian-2-yl)propan-2-one(C3).This dynamic behavior of PI and P4 was attributed to the concentration-dependent retro-Michael addition reaction between a thiol and a β-sulfido-α,β-unsaturated carbonyl compound catalyzed by bases.Furthermore,polymers P1 and P4 could be depolymerized into Cl and C4 in yields of 58% and 95%,respectively.The ring-opening polymerization of Cl at high concentration could successfully regenerate polymer PI.Thus,a new type of closed-loop recyclable poly(dithioacetal)s was developed.

关 键 词：Poly(dithioacetal)s Nucleophilic thiol-yne"click"polyaddition Chemical recycling Ring-chain equilibrium 

分 类 号：TQ316.3[化学工程—高聚物工业]