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.

Effect of Extra Gas Amount on Liquid Outflow from Hydrophobic Nanochannels: Enhanced Liquid–Gas Interaction and Bubble Nucleation

“…The gas molecules in nanochannels tend to form clusters and trigger liquid outflow. In our previous works, , it has been demonstrated that reduced gas solubility in the bulk liquid phase combining with enhanced gas oversolubility in the confined liquid phase preserves more gas molecules in the nanochannels and endows the LN system with higher degree of liquid outflow. Sun et al also reported that liquid outflow has been improved by hindering the time-dependent mass transportation in the nanochannels.…”

The Effect of Surface Entropy on the Heat of Non-Wetting Liquid Intrusion into Nanopores

“…The complete extrusion of liquid takes place upon the consecutive rapid , decompression of the system with repeated compression-decompression cycles showing the same reproducible behavior to the first cycle. In general, the tested fluids showed the same large PV hysteresis, which describes the material as a molecular shock absorber or bumper. − At 10 °C, water extrudes from the pore at a pressure of 1 MPa, while the ethanol solution extrudes at 0.2 MPa. Increasing the temperature of the experiment to 67 °C also increases the extrusion pressure of the ethanol solution to 1 MPa.…”

“…In general, the tested fluids showed the same large PV hysteresis, which describes the material as a molecular shock absorber or bumper. 13 − 18 At 10 °C, water extrudes from the pore at a pressure of 1 MPa, while the ethanol solution extrudes at 0.2 MPa. Increasing the temperature of the experiment to 67 °C also increases the extrusion pressure of the ethanol solution to 1 MPa.…”

“…The thermal effect (heat) of intrusion-extrusion is a fascinating phenomenon, which is generated when a non-wetting liquid is spread over a lyophobic nanoporous material’s surface. − The phenomena of wetting and de-wetting and its related effects are relevant for various applications such as molecular springs, ,, nanobumpers, − porosimetry, column chromatography, , reusable energy absorbers, , and self-cleaning behavior − and have been exploited for enhanced oil recovery . From a molecular perspective, the non-wetting liquid prefers to interact with molecules of its own kind (cohesion) rather than associate with those of the solid interface material (adhesion).…”

Long‐Lived Liquid Marbles for Green Applications

“…These are systems comprising of a liquid and a hydrophobic nanoporous material. [201,202] The result of this system is a highly efficient energy absorbent material with rapid energy dispersion, caused by liquid infiltration. When a sufficiently high external impact was experienced, the surface energy barrier was overcome, and liquid molecules entered the nanopores.…”