Thermally conductive under-liquid adhesives via the synergistic effect of intrinsic interfacial toughness and mechanical dissipation†

An under-liquid adhesive combining strong adhesion and enhanced thermal conductivity is crucial for applications like data center liquid cooling, underwater sensors, and batteries. However, weak and unstable adhesion in an under-liquid environment greatly limits thermal stability and reliability. To address this challenge, we report a strategy to achieve strong adhesion of a polydimethylsiloxane/aluminum adhesive through integrating tough dissipative composite matrices and strong interfacial linkages. The polydimethylsiloxane/aluminum adhesive shows excellent adhesion properties (an adhesion strength of 8.05 ± 0.21 MPa and an adhesion energy of 2160.20 ± 197.19 J m⁻²). This is attributed to strong covalent bonds that prevent propagation and extension, while dynamic hydrogen bonds undergo sequential rupture and reconstruction and induce crack blunting, synergistically improving the intrinsic interfacial toughness and mechanical dissipation. Notably, the adhesive demonstrates excellent durability and effectiveness after 1000 h of immersion in a 100 °C coolant. Highly filled spherical aluminum particles form a thermally conductive network in the polydimethylsiloxane matrix, achieving a thermal conductivity (4.30 W m⁻¹ K⁻¹). Combined with the liquid cooling strategy, the adhesive achieves a heat transfer coefficient of 2941.17 J m⁻² K⁻¹ s⁻¹, which has bright performance in the existing materials. This work presents a generalizable strategy for engineering stable, strong and thermally conductive adhesives, with significant potential for under-liquid applications.