Substantial improvement of thermal conductivity and mechanical properties of polymer composites by incorporation of boron nitride nanosheets and modulation of thermal curing reaction

Thermal conductive polymer-based composites synchronously with stable dielectric and excellent mechanical properties are urgently needed for high-temperature-resistant electronic devices. Here, a significant improvement in the thermal conductivity (TC), thermal stability, dielectric, and mechanical performance was simultaneously achieved in the polyarylene ether nitrile (PEN)/divinyl siloxane-bisbenzocyclobutene (BCB) matrix through the incorporation of boron nitride nanosheets (BNNS) combined together with the post-solid phase chemical reaction technique. The significant increase in the effective filler-filler and filler-crystal contacts in the composites was the main reason for the improvement in TC and dielectric constant. Besides, glass transition temperature (T-g) and mechanicals were enhanced in the presence of cross-linked networks. By synchronously adding 15 vol% BNNS, the TC of composites after treatment reached up to 5.582 W/m.K, enhanced by 4.4 times higher than untreated. The dielectric constant was down to 2.93 at 1 MHz and the loss remained at a relatively low level. Meanwhile, the composite showed significantly enhanced thermal stability, mechanicals, and hydrophobicity (T-g = 336 degrees C, T-5% = 529 degrees C, tensile strength and modulus was 94.5 MPa and 5.3 GPa, respectively, the contact angle was 101.76 degrees). Thus, it promotes an effective strategy for fabricating a high-performance-polymer composite, which has the potential used in electronic materials.