Enhancement on thermal management and mechanical properties of cellulose nanofiber films through synergistic filler construction and interface optimization

Abstract This study is aimed at developing composite films with superior thermal management performance in an attempt to solve challenge rising from heat accumulation in modern high‐frequency broadband communication devices. To effectively address the interface thermal resistance (ITR) of graphene nanoplatelets (GNPs) in the composites, cobalt nanoparticles were coated onto edge‐oxidized graphene to in‐situ form a hybrid filler (EGO@Co), which was then uniformly incorporated into the carboxymethyl cellulose nanofiber (c‐CNF) matrix. A vacuum‐assisted filtration was employed to fabricate EGO@Co/c‐CNF thermally conductive multi‐layered composite films. In‐situ growth of heterogeneous structure filler Co helped to extend the thermal paths and optimize the heat transfer networks. The incorporation of edge oxidation was found to facilitate the strong hydrogen bonding interactions between filler and matrix, constructing an efficient three‐dimensional (3D) thermal conduction network, significantly enhancing both heat flux and stress transfer efficiency. After hot‐pressed, the EGO@Co40/c‐CNF films exhibited an outstanding thermal conductivity (λ_ǁ ~ 28.4 W m⁻¹ K⁻¹ and λ_⊥ ~ 1.1 W m⁻¹ K⁻¹) in addition to a high tensile strength. The optimization on the thermal filler construction and interface modification have proved to significantly enhance the microstructure and properties of the composite films, which helps to pave the way for practical opportunities in the application of novel thermally conductive materials in the TMMs fields. Highlights Cobalt nanoparticles enhanced thermal conductivity of composites. EGO strengthened filler‐matrix hydrogen bonding. Vacuum‐assisted filtration produced multi‐layered composite films. EGO@Co/c‐CNF films displayed high thermal conductivity. Thermal filler optimization boosted mechanical and thermal properties.