Palladium/silver Composite Catalytic Polymerization Of 1-chloro-2-substituted Phenylacetylene And Its Post-modification

For the preparation of functional poly(disubstituted acetylenes)(PDSAs),catalyst system is one of the chanllenges.Traditional effective catalysts such as WCl6,MoCl6 and TaCl5 are sensitive to moisture,oxygen and polar functional groups.Because of the low oxophilicity of N-heterocyclic carbenes,the development of palladium catalysts in the field of the polymerization of 1-chloro-2-substituted phenylacetylene is a breakthrough,the direct polymerization of PDSAs containing functional groups can be attempted.On the other hand,the exploration of the post polymerization modification is an indirect but effective way to solve the problem.Therefore,the polymerization of 1-chloro-2-substituted phenylacetylene using an NHC-Pd/AgOTf catalyst and post-polymerization modification were further explorated.First of all,we prepared poly(1-chloro-2-substituted-phenyl acetylene)(PCSA)derivatives,where the substituents were tert-butyl,p-trimethylsilyl,m-trimethylsilyl and electron-withdrawing groups such as acyl,aldehyde,cyano and nitro.Especially,among a series of catalyst systems we have used,we successfully synthesized a novel PCSA derivative containing aldehyde group by using a NHC-Pd/AgOTf complex catalyst.Meanwhile,the aldehyde has been employed as reaction site for post-polymerization modification(PPM)and the highly efficient aldehyde-amine condensation leads to the Schiff-base functionalized PDSA with improved properties.At the end,we designed and synthesized PCSA derivative bearing a-bromo ester group using Pd/Ag catalyst.The use of a-bromo ester as an efficient PPM platform for the preparation of functional PDSAs was described.The a-bromo ester-containing polymer could be efficiently functionalized through thio-bromo "click" and tetramethyl guanidine promoted esterification,or act as an atom transfer radical polymerization(ATRP)initiator to synthesize grafted copolymers/polymer-brushs which consist of a PDSA main chain.