Conversion of mechanical work to interfacial tension in a nanoporous silica gel

A calometric measurement is performed to analyze energy exchange in a nanoporous material functionalized (NMF) liquid. As an external pressure is applied, the hydrophobic nanopore surfaces can be exposed to the liquid phase. When the pressure is removed, the system does not return to its initial configuration. Unlike ordinary energy absorption systems, no significant temperature variation can be detected during the infiltration of pressurized liquid water, indicating that the sorption process is nonexothermic. This is attributed to the conversion of mechanical work to excess solid-liquid interfacial tension.