Eco-friendly and scalable strategy to design electrically insulating boron nitride/polymer composites with high through-plane thermal conductivity. (1st January 2023)

• Record Type: Journal Article
• Authors: Jang, Wooree; Lee, Seoyun; Kim, Nam Ryeol; Koo, Hyeyoung; Yu, Jaesang; Yang, Cheol-Min
• Is Part Of: Composites. Number 248(2022)
• Publication Date: 2023-01-01
• Subjects: Polymer composite -- Boron nitride -- Core-shell microsphere -- Filler orientation -- Through-plane thermal conductivity; Composite materials -- Periodicals; Materials science -- Periodicals; Composite materials; Periodicals; Electronic journals; 620.118
• DOI: 10.1016/j.compositesb.2022.110355
• Languages: English
• ISSNs: 1359-8368

Abstract

Abstract: Hexagonal boron nitride (h-BN)/epoxy composites with high through-plane thermal conductivity were successfully fabricated using core-shell h-BN/epoxy (e-BN) microspheres which were synthesized using a simple one-pot emulsion polymerization process in an eco-friendly aqueous medium. e-BN microspheres covered with self-assembled h-BN flakes (1 μm lateral size) on the surface of the epoxy microspheres facilitated the effective alignment and distribution of the flakes in the epoxy matrix. The e-BN/BN/epoxy composites fabricated by mixing the e-BN microspheres with the h-BN flakes (17 μm lateral size) exhibited far higher through-plane thermal conductivity than the BN/epoxy composites (without e-BN microspheres) with the same h-BN flake content. In particular, the e-BN/BN/epoxy composite with 50 wt% (33 vol%) h-BN flakes exhibited excellent through-plane thermal conductivity of 4.27 W/mK, which was approximately 3.7 times that of the BN/epoxy composite (1.17 W/mK), owing to a more random or isotropic orientation of the h-BN flakes in the e-BN/BN/epoxy composite. The experimentally measured thermal conductivities were well matched to those obtained from micromechanical estimations using the modified Mori-Tanaka method. We expect that this eco-friendly and scalable fabrication process of e-BN microspheres and e-BN/BN/epoxy composites could provide an innovative strategy for manufacturing electrically insulating polymer composites with high through-plane thermal conductivity. Graphical abstract: Image 1 Highlights: Core-shell BN/epoxy (e-BN) microspheres were fabricated. BN/epoxy composites were fabricated by mixing e-BN microspheres with h-BN flakes. Insulating BN/epoxy composites showed excellent through-plane thermal conductivity. Thermal conductivity data were well matched to micromechanical estimation data.