Recyclable thermally conductive nanocomposites based on interpenetrating network of boron nitride nanosheets and nanoribbons

Technological advancements have significantly accelerated the development of high-performance thermal interface materials (TIMs), consequently leading to an increase in electronic waste (e-waste) generation. The recyclability of TIMs has thus emerged as a pressing concern. In this work, we propose a recyclable TIM constructed by an ordered interpenetrating structure composed of boron nitride nanosheets (BNNS) and boron nitride nanoribbons (BNNR). Functionalized BNNS (f-BNNS) were immobilized onto a melamine sponge (MS) skeleton using iteratively electrostatic layer-by-layer (L-B-L) assembly technique. Subsequently, BNNR were integrated within the f-BNNSx@MS framework to establish a three-dimensional (3D) binary BNNS/BNNR interpenetrating thermally conductive network through freeze-drying and hot-pressing. This method ensures robust thermal conductivity connectivity within the HDCN matrix. Thanks to the 3D BNNS/BNNR interpenetrating ordered thermal conductivity network, the f-BNNSx/BNNR@MS/HDCN (BBMH) nanocomposites demonstrate an outstanding in-plane thermal conductivity of 3.72 W center dot m-1K-1 at a BN loading of 45 wt%, representing a remarkable enhancement of 2076 % compared to pure MS/HDCN, and surpassing previously reported BN polymer composites with analogous loading levels. Furthermore, the incorporation of BN and MS contributes to the exceptional flame retardancy observed in the BBMH nanocomposites. Significantly, these nanocomposites enable efficient recycling of hybrid BN fillers in acidic environments. This work offers a novel strategy for designing recyclable and high-performance thermal interface materials.