Ion-mediated topological optimization of graphene fiber frameworks for high-performance thermal interface materials at ultralow loading

The escalating heat flux in miniaturized electronics requires high-performance thermal interface materials (TIMs) for efficient thermal management. However, conventional polymer composites suffer from a persistent trade-off between thermal conductivity, filler loading and processability. Herein, we report a novel Ca²⁺-mediated assembly strategy to fabricate topologically optimized graphene fiber frameworks (GFFs) for polydimethylsiloxane (PDMS) composites. By precisely regulating the fusion degree, this approach transforms discrete fiber networks into interconnected skeletons, establishing continuous through-plane phonon transport channels while minimizing interfacial scattering. Remarkably, the produced GFF/PDMS composite achieves a superior through-plane thermal conductivity of 5.91 W m⁻¹ K⁻¹ at an ultralow filler loading of only 2.5 wt%, representing a ∼30-fold enhancement compared to pure PDMS. More importantly, due to the established vertical conduction pathways and excellent surface conformability, the contact thermal resistance of GFF2/PDMS (55.11 K mm² W⁻¹) is reduced by one order of magnitude compared to commercial counterparts. Consequently, in real-time chip dissipation tests, the composite delivers exceptional cooling efficiency, yielding a substantial temperature reduction of 66.5 °C relative to the pure matrix. This work provides a scalable paradigm for constructing low-loading, high-efficiency thermal management materials via topological structure design.