Water Nanofilms Mediate Adhesion and Heat Transfer at Hematite-Hydrocarbon Interfaces

A detailed understanding of nanoscale heat transport at metal oxide-hydrocarbon interfaces is critical for many applications that require efficient thermal management. Under ambient conditions, water nanofilms are expected to form at these interfaces. Using molecular dynamics simulations, we show that water nanofilms at the hydroxylated hematite/poly-α-olefin (PAO) interface significantly affect wettability and thermal transport. Including water nanofilms improves agreement with experimental work of adhesion, which cannot be replicated with anhydrous systems using realistic solid liquid interactions. For water films thicker than one monolayer, interfacial thermal resistance (ITR) converges to a consistent value, independent of solid-liquid interaction strength. This value is dominated by the ITR at the water/PAO interface, due to strong hydrogen bonding between the water nanofilm and the hydroxylated surface. Our simulations provide a more precise estimate of ITR at the hematite/PAO interface by accounting for surface hydration expected in experiments under ambient conditions. This work offers crucial insights into the roles of surface hydroxylation and water nanofilms in controlling wettability and thermal transport at industrially important interfaces.