Post-Polymerization Modification Of (Meth) Acrylate Polymer

As a method of polymer preparation,post-polymerization modification has been widely used in the field of functional polymer synthesis.Through the post-polymerization modification of non-activated esters(polymethyl methacrylate,polytrifluoroethyl methacrylate,etc.),various functionalized poly(meth)acrylate polymers could be prepared directly.Compared with the method of preparing functionalized poly(meth)acrylate by polymerization of different organic small molecule monomers,post-polymerization modification uses transesterification or ammonolysis to react the cheaper raw material small alcohol or amine with non-activated ester.It can avoid the restriction caused by the double bond monomer in the homopolymerization or copolymerization reaction mode,and the experimental operation is simple and the reaction conditions are mild.Therefore,the use of post-modified polymerization methods to design functional polymers is of great significance.This thesis mainly studies the preparation of polyacrylamide copolymers by post-modification polymerization and the one-step synthesis of asymmetric hybrid molecular brushes.The polymerization kinetics and reaction mechanism are studied.The main contents are as follows:1.The polytrifluoroethyl acrylate(PTFEA)was prepared by free radical polymerization as a template compound for post-modification polymerization.1,8-diazabicycloundec-7-ene(DBU)and 1,2,4-Triazole(TA)are used as co-catalyst to catalyze the ammonolysis reaction of small molecular amines with PTFEA,and various polyacrylamide copolymers are prepared by post-modification methods.Experiments show that under the DBU/TA co-catalysis system,primary and secondary amines with different structural properties,such as isopropylamine,npropylamine,diethylamine,benzylamine,tetrahydropyrrole,cyclohexylamine,etc.,can all undergo aminolysis reaction with PTFEA to prepare poly acrylamide copolymers.When the co-catalyst DBU:TA=3:1 and 6 eq amine equivalent conditions,the post-polymerization modification of different small molecular amines in the polar solvent acetonitrile can reach the conversion rate of the ammonolysis reaction of more than 90% within 30 h.The experimental results show that by controlling the feeding amount of small molecule amine and polymer,reaction temperature,reaction time and catalyst dosage and other parameters,the ammonolysis reaction can be controlled,and polyacrylamide copolymers of different compositions can be obtained.The preparation of polyacrylamide copolymers by post-polymerization modification can effectively avoid side reactions such as cross-linking or chain coupling.2.The Atom Transfer Radical Polymerization(ATRP)is used to prepare polyhydroxyethyl methacrylate(PHEMA)homopolymer with suitable molecular weight and low polydispersity((?) < 1.20),which is used as a template compound for post-modification polymerization.Then use α-Bromoisobutyryl bromide to react with the hydroxyl group in PHEMA to obtain a side group with active sites for ATRP polymerization.Control the reaction conditions to obtain a series of macroinitiators with different-OH and-Br content in the side group(PHEMA-g-PBIEMA).Finally,DBU is used as both a catalyst for ring-opening polymerization(ROP)and a ligand for ATRP to realize a one-step preparation of asymmetric molecular brushes.The product was characterized by reaction kinetics,nuclear magnetic resonance and gel permeation chromatography.The experimental results show that in the preparation of asymmetric polymer molecular brushes with different structures,the ROP rate in the one-step system is higher than the ATRP rate,and the control of the reaction time and the initiator monomer can obtain molecules with different graft chain end lengths.brush.We also used thermogravimetry,differential scanning calorimetry and transmission electron microscopy to study the prepared polymers,and the experimental results further confirmed that we successfully synthesized asymmetric polymer molecular brushes.The amphiphilic asymmetric polymer molecular brush obtained by post-polymerization modification has the function of self-assembly.