The Influence Of Boron Nitride Network Construction On The Performance Of Thermal Conductive Composite Materials And Application Research

With the rapid development of modern technology,various power electronic devices are continuously moving towards miniaturization and multifunctionality,resulting in an increase in the density of electronic components.Under high-frequency operation,the accumulation of heat within electronic devices leads to frequent"thermal failures",which not only reduces the stability and service life of the equipment but can also cause safety hazards,such as fires.In order to achieve rapid heat dissipation in limited space,researchers have been exploring high-performance heat-conducting materials.In this regard,low cost and excellent performance of polymer based thermal conductivity composite materials have attracted much attention.Among them,the polymer matrix composites prepared with high thermal conductivity and thermal stability of boron nitride（BN）as thermal conductivity filler have attracted the attention of many researchers.However,how to effectively improve the thermal conductivity of the material with a lower filler content and increase the multifunctionality of the material is still a huge challenge.In this paper,the surface modification of BN was carried out to achieve its uniform dispersion in the polymer matrix and effective connection with the filler in the thermal conduction network.A series of thermal conductive composite materials with excellent thermal conductivity and good comprehensive performance were prepared,and the effect of BN loading on the performance of the composite materials was systematically studied.In addition,the mechanical properties and thermal stability of the materials were comprehensively investigated.PU skeleton with core-shell structure was prepared by water-based impregnation and coating process using PU foam bead templates.Functional BN（FBN）was deposited on dopamine（PDA）-coated PU skeleton to form PU@PDA@FBN（FPB）thermal network structure.The FPB skeleton was further vacuum-assisted infused with polydimethylsiloxane（PDMS）to prepare high thermal conductivity FPB/PDMS composite materials.The interface thermal resistance between the filler and the matrix was significantly reduced by pre-constructing the network,and the dual thermal conductive network structure at macroscopic and microscopic levels greatly improved the heat transfer efficiency.The thermal conductivity and mechanical properties of the composite material were synergistically improved,and it also had good thermal stability and electrical insulation properties.When the BN filling amount was 3.80 vol%,the vertical thermal conductivity of the FPB/PDMS composite material reached 0.70W·m^-1·K^-1,and the compressive strength and Young’s modulus were increased to 11.28MPa and 26.33 MPa,respectively.The toughness of PDMS was increased by 520%compared to the pure PDMS.PVA/SR polymer matrix was prepared using sericin protein（SR）with excellent biocompatibility and PVA with excellent mechanical properties by changing the ratio of the two components to increase the compatibility between the two phases,and the optimal film-forming ratio was found to be 1:1.FBN@PDA was mixed with the matrix by solution blending,and a highly oriented FBN@PDA/PVA/SR（FPPS）thermal conductive composite film was prepared by evaporation-assisted self-assembly and hot-pressing strategy.The in-plane thermal conductivity was increased to 12.11W·m^-1·K^-1 by adjusting the filler ratio and film thickness.In addition,the FPPS film has good mechanical properties,with fracture strength of up to 64.9 MPa and storage modulus of up to 5.07 GPa.The cotton fabric was functionally modified by the"dip-roll-dry"process,and a series of BN and nanofibrillated cellulose（NFC）/FBN solutions with different concentrations were designed to obtain the optimal finishing process.The modified cotton fabric prepared under the optimal process exhibited significant improvements in thermal conductivity and cooling performance,with an in-plane thermal conductivity of6.93 W·m^-1·K^-1 and q max of 0.27 J/cm²·s.This has certain guiding significance for the application of personal thermal management cooling textiles.In addition,using FPB/PDMS to simulate the thermal management system of electronic devices,it was used as a thermal interface material（TIMs）for LED chips,effectively reducing the surface temperature of the LED chips and greatly accelerating heat dissipation,demonstrating enormous prospects for thermal management applications.