Boron nitride self-assembly cladding structure promoting thermal property and dimensional stability of polymer composites

Abstract

A common problem in thermal conductive materials is poor interface compatibility between fillers and the matrix, which has caused high interfacial thermal resistance and lower thermal conductivity than expected. In this work, highly reactive graphene oxide (GO) was introduced as a bridge to simplify the complex surface treatment between inactive boron nitride (BN) and inert polyolefin matrix. Through electrostatic self-assembly and rapid alkylation modification in aqueous solution, the BN coated by modified GO (BN@MGO) is acquired. After treatment, the surface concentration of C element has increased for an order of magnitude, which builds a strong interface interaction between fillers and polypropylene (PP). Later in-situ reduction improved phonon matching of hybrid fillers and furtherly reduced phonon interface scattering. The effects of structure and dispersion on performance were characterized. The thermal conductivity of PP/BN@RGO composites is 22.8 and 1.9 times higher than that of the raw PP and PP/BN, respectively. Modified Hashin-Shtrikman model demonstrates that PP/BN@RGO composites possess lower thermal resistance. Tortuous path effect and high thermal stability make the composites exhibit highly flame-retardant property. The thermal expansion coefficient of the material is also effectively reduced to 26.58 ppm/°C. The comprehensive features of PP/BN@RGO make it a promising material with broad potential in highly efficient heat dissipation electronic equipment, household appliances and thermal management field.