Bio-inspired spiral-structured poly(vinyl alcohol)/liquid metal/carbon nanofiber composites for efficient thermal management

Abstract

Liquid metals (LMs) have garnered significant interest for developing LM-fillerd flexible composites due to their high thermal conductivity and fluidity. However, their propensity to leak and the associated difficulty in building a continuous vertical thermal network seriously hamper the development of high-performance LM-based thermal interface materials. Inspired by the spiral structure of fern fronds, this study first fabricated a sandwich-structured composite by sandwiching a hybrid filler of LM doped with one-dimensional carbon nanofibers (CNFs) between two PVA layers via a layer-by-layer coating process. Subsequently, the sandwich film was further processed into a PVA/LM-CNF composite with a continuous spiral structure through a combined rolling and hot-pressing process. Benefiting from the dual advantages of effective LM confinement from the sandwich architecture and a continuous vertical thermal pathway constructed by the spiral network, the composite with an LM content of 12.5 vol.% achieved a through-plane thermal conductivity of 2.75 W m⁻¹ K⁻¹, which is approximately 5.6 times that of pure PVA. Finite element simulation confirmed that this material can significantly reduce the interfacial thermal resistance between the chip and the heat sink. Meanwhile, the composite simultaneously demonstrates favorable compressive resilience, excellent cycling stability, and recyclable green characteristics. This study provides a new strategy for developing LM-based thermal interface materials that integrate high thermal conductivity, excellent flexibility, and environmental friendliness.