Highly and Uniformly Thermal Conductive Phase Change Composites by Constructing the Bidirectionally Oriented and Interconnected Boron Nitride Nanosheet Network

The localized overheating of high-power and miniaturized electronic devices puts a pressing demand for developing organic phase change composites with rapid and uniform heat conduction. Herein, we constructed a bidirectionally oriented and interconnected boron nitride nanosheet (BNNS) network to obtain highly and uniformly thermal conductive phase change composites. The edge-center temperature gradient generated during freezing via a radial ice-template strategy actuated the BNNSs to radially align. The simultaneously appearing bottom-up temperature gradient induced BNNSs to closely stack along the vertical direction. The formed biaxially oriented and interlaced BNNS network in poly(ethylene glycol) (PEG) composites formed rapid and macroscopically uniform heat transfer pathways. The resultant phase change composite loaded with 5.1 vol % BNNSs exhibited the in-plane and through-plane thermal conductivities of 1.62 and 1.45 W/mK respectively, nearly 150% higher than that of the randomly distributed counterpart. The strong thermal conductive stability after intense thermal shock, favorable shape stability, and large latent heat were also gathered. Our work offers a valuable reference for developing desired thermal conductive phase change composites for efficient thermal management.