Nanopore size effect on critical infiltration depth of liquid nanofoam as a reusable energy absorber

Abstract

Liquid flow in nano-environment has been utilized as an advanced mechanism of energy absorption. While the process of liquid outflow from nanopores has been shown to have a significant effect on the system’s energy absorption efficiencies, its mechanism remains poorly understood. Here, we have studied the liquid defiltration behavior of liquid nanofoam (LN) systems by controlling the infiltration depth. The LN samples, composed of a different non-wettable liquid phase and hydrophobic nanoporous silica with wide pore size distribution, have been compressed in two different loading modes under the quasi-static condition, i.e., the single-step compression and consecutive-step compression. Considerably different mechanical behaviors have been observed in these two loading modes, suggesting that the liquid outflow from nanopores is determined by the critical infiltration depth D*. The nanopore size effect on D* is further studied by a consecutive-step cyclic test. It has been shown that D* increases as the pore size gets smaller, which is related to gas solubility and diffusion rate in the nano-environment. The electrolyte concentration and temperature dependences of the critical infiltration depth have also been investigated. These findings provide a better understanding of the liquid outflow from nanopores and can be exploited to facilitate the design of next-generation reusable energy absorption systems.