Effect of Surface Modification on Equilibrium Kinetics under Nanopore-Confinement: Application of the Material Time Concept.

Abstract

Nanoscale confinement leads to deviations from bulk-like behavior, primarily due to surface effects that become more pronounced with decreasing system size. Equilibration processes allow confined systems to recover macroscopic properties over time. In this study, we investigated how surface modification of anodic aluminum oxide (AAO) nanopores affects the equilibration behavior of the glass-forming liquid DC704. Nanopores were functionalized with 5 nm layers of Al₂O₃ or SiO₂ using atomic layer deposition (ALD). Equilibration was markedly slower in SiO₂-coated pores due to stronger host-guest interactions and a thicker interfacial layer. Moreover, despite differences in pore size, surface chemistry, and temperature jumps, we successfully applied the concept of material time to describe nonequilibrium phenomena in pores. These results support the validity and universality of this approach at the nanoscale. Our findings highlight the crucial role of surface interactions in confined glass systems and demonstrate that the material time concept extends beyond bulk glasses.