Based On Polyethylene Synthetic Macromolecular Chain Transfer Agent And Its Application

In recent years,research on polyolefin functionalization and modification have been given high attention,people want to improve its performance through physical or chemical modification methods.Polyolefin graft copolymer,which is composed of two or above different types of macromolecular chain,through chemical bond connection form the main chain and side chain for the structure of the polymer,is a kind of important functional polyolefin.With the rapid development of high polymer synthetic chemistry,beneficial exploration and new methods have been conducted,thus polyolefin grafted copolymer with clear design of the structure also have been synthesized.Living radical polymerization is widely applicated for most of alkene monomer in the solution polymerization polymer system or bulk polymerization.The polymerization process has the advantages of simple operation,mild conditions,good reproducibility,and therefore become an important method for preparing polymer.But problems still exist in living radical polymerization,so controlled/living radical polymerization has been exploited.Without strict control of reaction conditions but can synthesize narrow molecular weight distribution polymers,so it has become a main method to synthesize polymers with relative controllable molecular mass and structure.For the purpose of meet the high material functional and sexual variety of requirements,the most effective method is to combine existing polymer alloy to get both advantages of polymer.However,almost all polymers are mutual miscibility,difficult to mix all together in simple method.Therefore we cannot achieve the desired effect to produce separate for the macro view.In order to improve the intermiscibility of polymer system,many methods have been adopted,one of the most effective is to add graft and block polymers as the melting agent in the miscibility system.(1)Small molecule RAFT chain transfer agent S-1-dodecyl-S?-(?,??-dimethyl-??-acetic acid)trithiocarbonate(DDMAT)and S-1-(?,? ?-dimethyl-? ?-acetic acid)trithiocarbonate(BDATC)were synthesized by the method of RAFT.DDMAT,as chain transfer agent,were triggered styrene(St)or styrene(St)and maleic anhydride(MA)polymerization throughregulating weight ratio.And different molecular weight of copolymer PS and P(St-MA)have been got.The product properties were characterized by high temperature hydrogen nuclear magnetic resonance spectrum(1H NMR),high temperature gel permeation chromatography(GPC),Fourier transform infrared spectrum(FT-IR)for analysis.(2)The EVA hydrolyzate EVAL was synthesized by the transformation of hydroxyl on the side chain for macromolecular initiator system EVAL-CTA.Due to the macromolecular initiator molecules has the similar functional groups with small one: three sulphur ester groups.A RAFT polymerization was actuated through EVAL-CTA of styrene and maleic anhydride.And functional polyolefin block copolymer EVAL-g-P(St-co-MA)was prepared.The product properties were characterized by high temperature hydrogen nuclear magnetic resonance spectrum(1H NMR),high temperature gel permeation chromatography(GPC),Fourier transform infrared spectrum(FT-IR)and Raman spectra for analysis.(3)After viewing the cryofractured sections of the two mixture systems LDPE/PS and LDPE/PS/EVAL-g-P(St-co-MA)via SEM,EVAL-g-P(St-co-MA)is tested to be a good compatibilizer.EVAL-g-P(St-co-MA)can effectively improve the surface energy of two incompatible polymer material.The results indicate that the graft copolymer EVAL-g-P(St-co-MA)can be synthesized via RAFT of styrene and maleic anhydride using the macroinitiator EVAL-CTA under 80 ?,and the reaction time is 20 h.The obtained copolymer can be applied as compatibilizer in the blend systems of LDPE/PS.