Design and properties of graphene film/polymer square-wave-like composites

The ordered arrangement of graphene sheets can make full use of the high in-plane thermal conductivity ( k) of graphene. However, the aligned channels are discretely distributed on the vertical surface, causing a height difference. Introducing a high-k horizontal interface for orientated structures is helpful in increasing the effective contact areas between hot spots and vertical pathways. Normally, the horizontal surfaces combing with ordered structures discontinuously were designed and prepared by coating or direct filling, causing additional thermal contact resistance (R_c). Hence, we developed a square-wave-like structure (S-S) introducing the continuous high-k plane based on the vertically aligned structure. The S-S was constructed by a simple and effective origami technology, taking advantage of the flexibility and machinability of graphene films (GFs), while incorporating polymer. To further enhance effective contact, a double square-wave-like structure (DS-S) was designed. The DS-S exhibited a k of 60.56 W m⁻¹ K⁻¹ (graphene loading 8.60 vol%), reducing the R_c by ∼30 % compared with S-S. Moreover, the single-sided DS-S with a thickness of 5 mm achieves an electromagnetic interference shielding effectiveness above 50 dB. Thereby, the novel strategy for designing thermal interface materials (TIMs) presented in this study can be utilized to prepare TIMs for advanced electronic packaging.