Study On The Structure And Properties Of In Situ Polymerized Graphene/Benzoxazine Blends

With the rapid development of the electronics industry,high-dielectric materials with excellent uniform electric field and electrical storage capacity are widely used in high-charge storage capacitors,printed circuit boards,various sensors and other electronic industries,as well as in electrostrictive artificial muscles,and microelectronics for drug delivery.Intelligent systems such as fluid systems and drag-reducing"smart skins"have enormous potential for application.Traditional ceramic dielectric materials have high dielectric constants,but their dielectric losses are large and their mechanical properties and processability are poor.However,the composite materials prepared by introducing high-conductivity nanomaterials based on polymers have attracted widespread attention due to their excellent dielectric properties and ease of processing.As a new type of high-performance phenolic resin,benzoxazine has many unique advantages.Compared with other polymer matrices,benzoxazine complements its poor mechanical properties,insufficient heat resistance,difficult processing,The higher price is insufficient.Generally speaking,it is difficult for a material to have good dielectric properties,mechanical properties,processing properties and other comprehensive properties.Polymers generally have good mechanical properties and processing properties,but most of them are insulators,and their dielectric constants are generally higher.Low.In order to meet the requirements of high-dielectric materials,composite materials prepared by introducing other materials into high-molecular polymers as the matrix can improve their dielectric properties while maintaining the advantages of the polymers themselves,so as to obtain high-dielectric polymers with excellent comprehensive properties.material-based composites.Graphene is a potential conductive filler.When graphene is compounded with polymers,generally a lower amount of graphene can make the composite material have a higher dielectric constant,while maintaining good polymer properties.Processability and mechanical properties.Graphene directly and efficiently exerts excellent electrical conductivity in benzoxazine,and its dispersion problem is a key problem to be solved urgently in the preparation and application of this system.In order to improve the dielectric properties of benzoxazine and solve the dispersion problem of graphene in benzoxazine matrix,the work of this paper is as follows:(1)Using the electrostatic interaction between the phenolic hydroxyl groups of m-cresol and reduced graphene oxide,a solvent-free method was used to synthesize a monooxazine ring benzoxazine resin with m-cresol containing reduced graphene oxide as the phenol source,in situ dispersion of reduced graphene oxide in benzoxazine resin systems was realized.The blends were systematically studied by hydrogen nuclear magnetic resonance spectroscopy(~1H-NMR),FTIR,rheology,DSC,vector network analyzer.The research results show that the in-situ dispersion method does not affect the synthesis of benzoxazine monomers.At the same time,compared with the traditional solution blending method,the in-situ dispersion method can not only achieve a more uniform dispersion of reduced graphene oxide,but also Moreover,the obtained composite material has better processability and lower curing reaction temperature(the curing temperature(225.72°C)of the blend system with 2wt%in-situ addition of reduced graphene oxide is relatively lower by 21°C),at 8.2-12.4 GHz,there is a higher dielectric constant((8.69 k)relative improvement of 0.79 k),higher electromagnetic shielding value((7.45d B)relative improvement of 0.75d B)and faster heat dissipation rate in the same environment(about 2°C faster at the same time point).Subsequently,optical microscopy and SEM results further confirmed the effect of this method to achieve uniform dispersion of reduced graphene oxide in benzoxazine.Thus,a method for uniformly dispersing reduced graphene oxide in benzoxazine without any solvent and without any treatment is provided.(2)Using the electrostatic interaction between the phenolic hydroxyl groups of m-cresol and reduced graphene oxide,a dioxazine cyclobenzoxazine resin with m-cresol containing reduced graphene oxide as phenol source and 4,4'-diaminodiphenylmethane as amine source was synthesized by solvent method,and the in-situ dispersion of reduced graphene oxide in Benzoxazine Resin System was realized.The blends were systematically studied by hydrogen nuclear magnetic resonance spectroscopy(~1H-NMR),FTIR,DSC,vector network analyzer.The results show that the in-situ dispersion method does not affect the synthesis of benzoxazine monomers,and at the same time,compared with the traditional solution blending method,this method not only achieves a more uniform dispersion of reduced graphene oxide,but also produces the composite material has a lower curing reaction temperature(the curing temperature(245.95°C)of the blend system with 2wt%in situ addition of reduced graphene oxide is relatively lower by 5°C),at 8.2-12.4 GHz there is a higher dielectric constant((8.55k)a relative improvement of 1.18 k)and a higher EMI shielding value((6.47 d B)a relative improvement of 0.48 d B).Subsequently,SEM results further confirmed the effect of this method to achieve uniform dispersion of reduced graphene oxide in benzoxazine.This further confirms that the reduced graphene oxide provided by the previous work can be uniformly dispersed in benzoxazine without any solvent and without any treatment,which provides a new way to further improve the performance of composite materials.