Robust polymer-based paper-like thermal interface materials with a through-plane thermal conductivity over 9 Wm−1K−1

Great progresses have been achieved in paper-like highly thermally conductive films with high in-plane thermal conductivity (k), but their applications are still limited by the unsatisfactory through-plane k (0.05–2 Wm−1K−1). In practical applications, paper-like robust composites with high through-plane k, instead of bulk materials, are highly desired for thermal interface materials (TIMs). In this work, flexible bacterial cellulose (BC) based paper-like composites with an ideal-thermal-transportation structure, in which a single-layer Al2O3 particles are confined in the through-plane direction of the films and the Al2O3 particles are covered by highly thermally conductive graphene nanoplatelets (GNPs), are fabricated by a facile vacuum-assisted self-assembly method. The films exhibit the highest through-plane k value (9.09 Wm−1K−1) among reported polymer-based paper-like composites, excellent flexibility (in over 20,000 bending cycles) and robust mechanical properties (tensile strength ~10.6 MPa and elongation at break ~7.6%). The outstanding heat management capability of the fabricated films is demonstrated by demonstrative experiments and finite volume simulation, clearly showing the great potential to be used as super TIMs in advanced electronic packaging technology.