Synthesis And Application Of Pyrene-based And Epoxy-based Hyperbranched Polyethylene In Epoxy Resin

As a traditional material,epoxy resin has good adhesion,good heat resistance and chemical resistance,and is widely used in various fields.However,at the same time,its brittleness,poor thermal conductivity and electrical conductivity greatly limit its application.Many modern technologies often directly apply new materials with excellent performance to the frontier.However,new materials require high capital investment,and composite modification using traditional materials is still the most ideal method.However,the ability to achieve efficient modification of epoxy resin is a key factor in its application in high-end and fine-grain applications.This paper use the Pd-diimine catalyst under 0.1 MPa/25℃catalytic pyrene and functional monomer monomers and BIEA monomer based on the“chain walking”mechanism,one-step synthesis of bromine containing multiple acyl groups at the end of the HBPE@Py@Br of hyperbranched polymer,with HBPE@Py@Br for macromolecular initiator,through the method of ATRP caused methyl glycidyl ester of acrylic(GMA)monomer copolymerization,the preparation of the hyperbranched HBPE@Py@PGMA polyethylene copolymer.The fluorescence and mechanical properties of HBPE@Py@PGMA and epoxy resin were studied.At the same time,HBPE@Py@PGMA liquid phase was used to strip the graphene,and the thermal conductivity of the functionalized graphene was studied after composite modification with epoxy resin.Matrix studies are as follows:(1)Using Pd-diimine catalyst to catalyze ethylene,pyrene monomer and BIEA monomer based on the"chain walking"mechanism at 0.1 MPa/25℃,hyperbranched polymer HBPE@Py@Br with multiple acyl bromide groups at the end was synthesized in one step.HBPE@Py@Br was used as the macromolecular initiator to trigger GMA monomer copolymerization by ATRP method,and hyperbranched polyethylene copolymer HBPE@Py@PGMA was prepared.Its structure and composition were characterized by hydrogen nuclear magnetic resonance spectroscopy(~1H NMR),Fourier infrared spectroscopy(FTIR)and gel permeation chromatography(GPC).The results show that the graft rate of pyrene monomer and BIEA monomer in hyperbranched structure and hyperbranched topological structure can be effectively controlled by adjusting the feeding ratio of pyrene monomer and BIEA monomer and controlling the change of temperature.Moreover,by adjusting the polymerization time of ATRP,the molecular weight,grafting rate and chain morphology of HBPE@PGMA could be effectively controlled.(2)The prepared pyrene hyperbranched polymer HBPE@Py@PGMA was used to study the influence of the concentration of the polymer and the volume fraction of the bad solvent on its fluorescence performance.Meanwhile,HBPE@Py@PGMA was compounded with epoxy resin to study the influence of different polymer filling ratio on its fluorescence performance and mechanical properties.The fluorescence properties of the polymer and epoxy composite materials were characterized by fluorescence spectrum,the fluorescence dispersion of the epoxy resin composite film was characterized by fluorescence inverted microscope and scanning electron microscope,and the mechanical properties of the epoxy resin composite film were characterized by high and low temperature double-column tension machine.The results show that HBPE@Py@PGMA exhibits a typical aggregation enhanced excimer emission(AEEE)phenomenon.HBPE@Py@pPGMA has excellent compatibility with epoxy resin.A small amount of it can be added to give epoxy resin good fluorescence performance and improve its toughness significantly.The epoxy resin is expected to be used as a packaging material for optical devices.(3)Disperse and stable graphene solution was obtained by ultrasound-assisted graphite stripping in solution by HBPE@Py@PGMA polymer.The effects of solvent,polymer feeding,graphite feeding and ultrasonic time on the stripping concentration and efficiency of graphene were also investigated.The thermal conductivity of functionalized graphene was studied by composite with epoxy resin.The concentration of graphene was characterized by uv-vis spectroscopy,the size distribution and morphology of graphene was characterized by TEM,and the structure and defects of graphene were characterized by X-ray diffraction(XRD)and Raman spectroscopy.The interaction between graphene and hyperbranched polymer was characterized by TG,FTIR and fluorescence spectra.Finally,the thermal conductivity of the composite film was studied by laser thermal conductivity instrument.When HBPE@Py@PGMA concentration was 1 mg/mL and graphite concentration was 8mg/mL,the highest concentration of graphene dispersion obtained after 48 h ultrasound was 0.26 mg/mL,and the graphene yield was 3.2%.The size of graphene is distributed between 100-400 nm,and mainly consists of 3-5 layers of oligogenic graphene.At the same time,graphene has fewer defects and a complete structure.PI PI forces exist between graphene and the polymer,as shown by the fact that 40 per cent of the polymer in graphene removed from the excess polymer was still present on the graphene surface.By compounding the obtained graphene with the epoxy resin solution,the graphene was evenly dispersed in the epoxy resin.When the graphene content was 4 wt%,the thermal conductivity increased by 415.6%.