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Tailored Thermal Transport in Phase Change Materials-Based Nanocomposites through Interfacial Structuring

Interfacial thermal transport is a critical bottleneck in nanoscale systems, where heat dissipation and energy efficiency are strongly modulated by molecular ordering at solid-liquid boundaries. Here, using atomistic simulations of hexadecane confined by structured silica substrates, we reveal how interfacial geometry, specifically curvature, governs the density distribution and thermal transport across the interface. On flat and mildly curved surfaces, the liquid exhibits surface-templated layering, promoting efficient heat transfer, which is enhanced as the contact surface area increases. As curvature increases, this ordering breaks down, giving rise to interference-like density patterns, reduced molecular packing, and localized depletion zones. This structural reorganization leads to a systematic increase of up to 10 % in interfacial thermal resistance (ITR), even when the contact area is kept constant. By decomposing the interface into convex ("hills" of the solid) and concave ("valleys" of the solid) regions, we find that valleys consistently exhibit lower ITR. In contrast, hills act as bottlenecks to heat flow, leading to interfacial thermal resistance values up to 70% higher than those of valleys, depending on the surface configuration. Remarkably, we show that the work of adhesion and entropy-related energy gain upon liquid detachment scale non-trivially with curvature: while adhesion increases with contact area from 30 mJ*m^(-2) for a flat surface to 40 mJ*m^(-2) for a maximum curvaceous surface, the entropic penalty dominates the total energy change, reflecting curvature-induced frustration of molecular alignment.