Enhanced thermal conductivity of boron nitride nanosheets-composite hydrogel via mechanically induced orientation for heat management in electronic devices

Thermal interface materials are critical for heat management in compacted electronic devices. To address the heat accumulation challenges posed by ongoing trends of integration and miniaturization, we developed a composite hydrogel with high thermal conductivity by incorporating well-dispersed boron nitride nanosheets (BNNS) into semi-interpenetrating. polyacrylamide-polyvinylpyrrolidone-polyacrylonitrile (PAM-PVP-PAN) hydrogel matrix. The hydrogel exhibits exceptional mechanical stretchability and durability which withstands up to 3450% tensile strain and 29 MPa stress. The synergistic combination of ductility from PVP and rigidity from polar cyano groups of PANs not only confers outstanding toughness and extensibility but also facilitates robust interfacial interactions with BNNS. By leveraging this mechanical performance, we propose a simple strategy to significantly enhance thermal conductivity through the mechanical orientation of the two-dimensional fillers. Through a sequential stretching-and-folding strategy, BNNS were effectively oriented within the matrix, constructing efficient heat-transfer pathways that substantially minimize interfacial thermal resistance and fully exploiting their anisotropic thermal properties. The in-plane thermal conductivity of the composite reached 10.88 W m⁻¹ K⁻¹ after five cycles of mechanical orientation, which is more than six times higher than that of the non-aligned state. When applied to a solar panel, the composite reduced operating temperature by over 10 °C compared to the bare panel. Combined with the advantages of strong adhesion, excellent water retention, and reliable electrical insulation, this developed thermal interface material shows promise for thermal management in portable and integrated electronic devices.