Enhancing thermal conductivity of polyimide composite film by electrostatic self-assembly and two-step synergism of Al2O3 microspheres and BN nanosheets

• Published in: RSC advances Vol. 10; no. 69; pp. 42584 - 42595
• Main Authors: Liu, Dongxu, Ma, Chuanguo, Chi, Hongtao, Li, Shihui, Zhang, Ping, Dai, Peibang
• Format: Journal Article
• Language: English
• Published: Cambridge Royal Society of Chemistry 24.11.2020; The Royal Society of Chemistry
• Subjects: Aluminum oxide; Boron nitride; Chemistry; Conducting polymers; Conduction heating; Conductive heat transfer; Heat conductivity; Microspheres; Nanosheets; Polyimide resins; Polymer matrix composites; Self-assembly; Thermal conductivity
• ISSN: 2046-2069
• DOI: 10.1039/d0ra08048a

To improve the perfection of a three-dimensional thermally conductive network in polyimide (PI) composite film and with respect to the economy and simplicity of processing, a strategy of the two-step synergism of Al2O3 microspheres and hexagonal boron nitride (BN) nanosheets was proposed. First, BN nanosheet-coated Al2O3 microspheres (Al2O3@BN) were prepared by electrostatic self-assembly method for the first step of the synergism. Then, the Al2O3@BN&BN/PI composite film containing Al2O3@BN and BN was fabricated by a two-step method for the second step of the synergism, and was systematically characterized. With an optimized mass ratio of 2 : 1 of Al2O3@BN to BN, the thermal conductivity of the 35 wt% Al2O3@BN&BN/PI composite film reached 3.35 W m−1 K−1, and was increased by 1664% compared to that of pure PI. The synergism of the Al2O3 and BN was the most significant in the Al2O3@BN&BN/PI composite film with the thermal conductivity, which was 36.6%, 23% and 22% higher than that of the Al2O3/PI, BN/PI and Al2O3@BN/PI composite films, respectively. The enhancement mechanism of heat conduction was clearly demonstrated. The BN coated on the surface of Al2O3 mainly played a bridging role between the Al2O3 and the BN network, which improved the perfection of the thermally conductive network. The Al2O3@BN segregated the PI matrix to construct the BN network with the typical segregated structure in the composite film, resulting in an efficient thermally conductive network. This work provided a novel strategy for the preparation of conductive polymer composites.