Study On Synthesis Of Block Polymers Of Acrylates And ε-Caprolactone

The preparation of block polymers is generally achieved by a"one pot method",in which two or more monomers are added sequentially to complete the polymerization.This type of reaction is usually achieved through the use of metal catalysts,but the metal catalysts used will still remain in polymers as metal components,which poses a poisoning risk for the subsequent application of polymers in biological and medical clinical fields.In order to avoid metal residues,living/controlled polymerization methods using organic catalysts have recently emerged to complete the preparation of block polymers.In this paper,group transfer polymerization（GTP）based on in situ 1,4-hydrosilylation was used to synthesize acrylic polymer macromolecules with hydroxyl terminal using organic non-metallic catalysts,thenε-Caprolactone（ε-CL）is used as a monomer to block by ring opening polymerization（ROP）.The block polymers with different structures were prepared by the combination of two polymerization methods,providing new polymerization methods and ideas for the synthesis of polyester block polymers with different structures and properties.The specific research contents are as follows:1.Using（5-ethyl-2,2-dimethyl-1,3-dioxane-5-yl）methanol（DOX-OH）as the structural framework,and organically synthesized with tiglic acid,tert-Butyldimethylsilyl chloride and benzyl chloride containing different substituent groups.The corresponding initiator precursors,2,2-bis（（（tert-butyldimethylsilyl）oxy）methyl）butyl（E）-2-methylbuty-2-enoate（TIG-TBDMS₂）and 2-（（benzyloxy）methyl）-2-ethylpropane-1,3-diyl（2E,2’E）-bis（2-methylbuty-2-enoate）（Bz-TIG₂）were prepared,and the structure was confirmed by ¹H NMR and ¹³C NMR tests.2.The SKA initiator corresponding to the initiator precursor was synthesized by GTP method based on in-situ 1,4-hydrosilylation.Methyl methacrylate polymers（PMMAs）were prepared using N-（trimethylsilyl）bis（trifluoromethanesulfonic acid）imide（Me₃Si NTf₂）as a catalyst and methyl methacrylate（MMA）as a monomer.In addition,n-butyl acrylate polymers（PnBAs）were prepared using tri（pentafluorophenyl）borane（B（C₆F₅）₃）as a catalyst and n-butyl acrylate（n BA）as a monomer.According to the deprotection property of the end group,the end group of the acrylate polymer was further removed,and the acrylate macromolecular initiator required for the next step of polymerization was obtained.Through¹H NMR and SEC tests,it was finally confirmed that acrylate polymers PMMAs,PnBAs with clear structure and narrow molecular weight distribution and four kinds of acrylate macromolecular initiators were synthesized.3.Using the ROP method for block polymerization,replacing different catalysts for comparison,exploring the selection of organic catalysts and reaction conditions during the polymerization process,and finally confirmed that diphenyl phosphate（DPP）was used as catalyst,macromolecular initiator andε-Caprolactone（ε-CL）reaction to synthesize AB block polymers（PMMA_m-b-PCL_n,PnBA_m-b-PCL_n）.Through ¹H NMR and SEC tests,block polymers PMMA_m-b-PCL_n and PnBA_m-b-PCL_n with clear structure and narrow molecular weight distribution were successfully synthesized.