Mussel-mimetic thermal conductive films with solid-solid phase change and shape-adaptive performance

Phase change thermal conductive materials have been applied as heat dissipation interface materials in new electronic devices owing to their high thermal conductivity, phase change energy storage performance, low energy consumption, renewability, and long service life. However, it is a huge challenge to achieve solid-solid phase change materials with high thermal conductivity, high latent heat of phase change, excellent shape stability, good shape adaptability, and high electrical insulation. Inspired by the "brick-mortar" structure and function of natural mussels, a solid-solid phase change thermal conductive film material was successfully constructed based on the self-assembly and self-crosslinking behavior of modified polyethylene glycol (CPEG) blended with oriented boron nitride (O-BN). The mussel-like O-BN/CPEG composite film (bio-composite film) was prepared using boron nitride micro-sheets as the "brick" and CPEG as the "mortar" through hot pressing and layer-by-layer stacking. The bio-composite film with a vertical arrangement of boron nitride micron sheets was obtained via longitudinal cutting, which had good shape stability and shape-adaptability, high out-of-plane thermal conductivity (12.05 W m(-1) K-1), low contact thermal resistance (<0.15 cm2 K W-1), high latent heat of phase transition (101 J g(-1)) and excellent electrical insulation (volume resistivity was greater than 1011 omega cm) when the BN load was only 20 vol%. The film could also be spliced together by heating, which was expected to yield a large-sized film with a vertical arrangement of BN. Compared with commercial thermal grease, the bio-composite thermal interface management films exhibited higher heat dissipation efficiency in cooling LED chips, and the bio-composite films had excellent heat management capability and stability in the heat dissipation of LED lamps with different powers. This method of constructing mussel-like thermally conductive films with oriented structures presents the potential for applications in the thermal management of chips, electronic devices, flexible wearable devices, new energy battery systems, and other new electronic devices.