Study On Micro-Nano Structure Regulation And Dielectric Properties Of Polyarylene Ether Nitrile Composites

In recent years,with the development of various renewable and sustainable energy sources,there is an urgent need to develop advanced electrical energy storage technologies for stable output and effective application in practical use.Among them,dielectric capacitors have attracted attention in the field of energy storage devices due to their advantages such as ultra-high power density,ultra-fast charge-discharge rate,excellent cycle stability,and long life.Polymer-based composite dielectrics have the advantages of being lightweight,having good flexibility,simple preparation process,and high dielectric constant of fillers,and have broad application prospects in the field of energy storage.As a new type of special engineering polymer,polyarylether nitrile(PEN)has excellent high-temperature resistance and high strength characteristics,and its main chain is rich in polar group cyano groups,making its intrinsic dielectric constant reach3.5-4.0,which has important practical value for the preparation of polymer composites with high dielectric properties.In this thesis,polyarylene ether nitrile matrix resins with different chain link structures and different morphological structures were first prepared through molecular structure design,and a variety of micro-nano resins with different micro-nano Structured functional fillers,polyarylether nitrile-based composite dielectric film materials were prepared by solution blending and casting techniques,and the effects of different micro-nano structured fillers and different aggregated structure polymer matrices on polyarylether nitrile-based composite films were explored in detail.Thermal properties,mechanical properties,dielectric and energy storage properties.1.Using hydroquinone(HQ)and biphenol(BP)as bisphenol monomers in the preparation of polyarylethernitrile,an amorphous polyarylethernitrile(HQ/BP-PEN)matrix was synthesized.The surface of nano-barium titanate was modified by zinc phthalocyanine rich in phthalocyanine groups,and its micro-nano structure was adjusted to prepare BT@Zn Pc nanoparticles with different zinc phthalocyanine shell thicknesses.Behavioral studies reveal the compatibility of BT@Zn Pc with HQ/BP-PEN matrix resin;the dielectric constant of the composite dielectric film can reach 6.05(electric field frequency is 1 k Hz),and the glass transition temperature(T_g)above 167°C.In order to further reduce the filling amount of the composite material,graphene oxide(GO)conductive material was selected to improve the dielectric properties of the composite dielectric material.Firstly,metal-organic framework(MOF)was grown on the surface of GO by in-situ growth method to obtain i-G@M material.MOF effectively improved the compatibility of GO and polymer matrix,and improved the agglomeration of GO.When the content of i-G@M is 4 wt%,the dielectric constant of the composite dielectric film reaches 8.02(at 1 k Hz),and the dielectric loss remains below 0.018.In addition,GO was introduced into BT@Zn Pc nanoparticles through electrostatic adsorption,and the BT@Zn Pc-GO micro-nanostructure was constructed.The filler content in BT@Zn Pc-GO/HQ/BP-PEN was 15 wt%,and the dielectric constant was It can be greater than 6.2,which is higher than the dielectric constant 6.05 of the 30 wt%BT@Zn Pc composite without introducing GO components,which opens up a new technical approach for high-performance functionalization and lightweight.2.Using HQ and RS as bisphenol monomers in the preparation of polyarylether nitrile,a crystallizable polyarylether nitrile(HQ/RS-PEN)was obtained by solution copolymerization-c)Base resin.By in-situ growth of polyurea(PUA)organic layer on the surface of nano-barium titanate,BT@PUA core-shell functional fillers were obtained,and BT@PUA/PEN composite films with different contents were prepared.Studies have shown that the PUA layer can improve the crystallization behavior of HQ/RS-PEN-c and effectively promote the crystallization ability of HQ/RS-PEN.After the composite film was isothermally heat-treated at 260°C for two hours,the crystallinity of the PEN composite film introduced with BT@PUA was as high as 14.9%,the melting enthalpy was 16.93 J/g,and the T_g was higher than 175°C,which significantly improved Thermal stability of BT@PUA/PEN composite films.When the filler content is 20 wt%,the dielectric constant reaches 6.71,which is 1.72 times that of the pure polymer.After isothermal crystallization treatment,the dielectric constant is further enhanced to 7.18,and the dielectric loss can be maintained at about 0.02.This excellent The dielectric properties have laid the experimental foundation for the further development of energy storage materials and devices.3.Using BP as the bisphenol monomer in the preparation of polyarylether nitrile,the polymer was capped with 4-nitrophthalonitrile to obtain a cross-linked polyarylether Nitrile(BP-PEN-ph)base resin.BT nanowires with high aspect ratio(BTnw)were synthesized by hydrothermal method and functionalized with cyano groups to prepare cyano-functionalized barium titanate nanowires with high aspect ratio(BTnw-CN).BTnw-CN/BP-PEN-ph composite films were prepared by solution blending.After isothermal treatment at 320°C for 4 hours,the one-dimensional BTnw-CN provided more cross-linking sites,co-cross-linked with the cross-linkable BP-PEN-ph matrix,and formed polyarylene ether nitrile with micro-nano structure in situ composite Material,the T_g of the composite film can reach 272.5°C,which is 42.3%higher than that before heat treatment,and has excellent temperature resistance.The intrinsic dielectric constant of BT nanowires is higher.When BTnw-CN in the composite film reaches 30 wt%,the dielectric constant reaches 12.1,and the loss remains below 0.035.After the composite film is crosslinked,the dielectric constant of 30 wt%BTnw-CN/BP-PEN-ph is still higher than 10,the dielectric loss is reduced to below 0.025,and the energy storage density reaches 1.99 J/cm~3,which is high temperature resistance.The further development and application of energy storage density capacitors provide material research ideas.4.Using biphenol(BP)and hydroquinone(HQ)as bisphenol monomers in the preparation of polyarylether nitrile,and capping the polymer with 4-nitrophthalonitrile to obtain A crystallizable cross-linkable polyarylether nitrile(HQ/BP-PEN-c-ph)matrix resin was developed.BTnw-CN/HQ/BP-PEN-c-ph composite films with different filler contents were obtained by compounding one-dimensional BTnw-CN with HQ/BP-PEN-c-ph matrix resin,after isothermal heat treatment,it can be obtained BTnw-CN/PEN-c-ph crystalline cross-linked film constructed a micro-nano composite material with a polymer crystalline cross-linked structure.Compared with the uncross-linked BTnw-CN/HQ/BP-PEN-c produced more perfect crystals,the introduction of high dielectric ceramic nanowires BTnw-CN significantly improved the dielectric constant of the composite film.After introducing 30 wt%BTnw-CN,the dielectric constant increased to12.11,and the dielectric loss remained below 0.035.When the composite film is crystallized and heat-treated,the dielectric constant is further improved.When the content of BTnw-CN is 30 wt%,the dielectric constant of the polymer composite film reaches12.76.Further heat treatment produces a cross-linked network structure,the dielectric constant is slightly reduced,and the dielectric loss is significantly reduced.At 30 wt%loading,the dielectric constant of BTnw-CN/HQ/BP-PEN-c-ph film is still higher than that of 11,the dielectric loss is reduced to below 0.025,and the energy storage density is as high as 2.13 J/cm~3,showing excellent dielectric properties and energy storage density.