Experimental Study on Energy Dissipation of Electrolytes in Nanopores

Abstract

When a nonwetting fluid is forced to infiltrate a hydrophobic nanoporous solid, the external mechanical work is partially dissipated into thermal energy and partially converted to the liquid-solid interface energy to increase its enthalpy, resulting in a system with a superior energy absorption performance. To clarify the energy dissipation and conversion mechanisms, experimental infiltration and defiltration tests of liquid/ion solutions into nanopores of a hydrophobic ZSM-5 zeolite were conducted. The characteristics of energy dissipation were quantified by measuring the temperature variation of the immersed liquid environment and compared against that estimated from pressure-infiltration volume isotherms during infiltration and defiltration stages of the test. Both stages were observed to be endothermic, with the temperature of the liquid phase showing a steady increase with changes in liquid saturation. The confinement of the molecular-sized pore space causes the liquid molecules/ions to transit between statuses of orderly and disorderly motions, resulting in dissipation behaviors that vary with liquid infiltration/defiltration rates and the types and concentrations of additive electrolytes in the liquid-both factors of which alter the characteristics of the nanofluidic transport behavior.

Improving hydrogels׳ toughness by increasing the dissipative properties of their network

“…Indeed, it has been shown that having hydrophobic properties along with nanoporous structure induces a special interaction between hydrogels chains and water composing the hydrogel that can highly increase the dissipation (Surani et al, 2005;Zhao et al, 2009;Kong and Qiao, 2005). For such a material immersed in water or in a nonwetting liquid, previous published studies showed that when external mechanical pressure exceeds a critical threshold, the liquid can be forced to defiltrate or infiltrated the hydrophobic nanopores (Surani et al, 2005;Zhao et al, 2009;Kong and Qiao, 2005). In other words, there will be a defiltration (drainage) and infiltration pressure during loading and unloading that increase interfacial energy.…”

“…In other words, there will be a defiltration (drainage) and infiltration pressure during loading and unloading that increase interfacial energy. In this situation, the forced in and out motion of the liquid molecules will increase the energy dissipation via friction-like interaction between solid and liquid phases (Surani et al, 2005;Zhao et al, 2009;Kong and Qiao, 2005). Beside the two specific properties related to solid-fluid interactions, the high dissipation of HEMA-EGDMA hydrogels could also be related to the sub-molecular structure of these hydrogels.…”

“…Hydrophilic materials show a spring-like behavior due to its high tendency to keep the water molecules (Surani et al, 2005;Zhao et al, 2009;Kong and Qiao, 2005). Under loading the friction like behavior related to water flow discussed earlier is less likely to happen to dissipate the input work.…”

“…In particular, these hydrogels can be produced with nanoscale pore size (Peppas et al, 1985). Nanopores provide a large pore surface area, which generates a unique nanofluidic behavior generating high friction between liquid and solid phase when the fluid flows through the nanopores (Surani et al, 2005;Zhao et al, 2009;Kong and Qiao, 2005).…”

Controlled release from a mechanically-stimulated thermosensitive self-heating composite hydrogel

“…In spite of hydrophilic nature of HEMA monomers, it is postulated that PHEMA hydrogel has, in addition to its covalently linked network structure, a secondary structure stabilized by hydrophobic bonding [30]. It has been showed that for a hydrophobic porous material, because of an defiltration (drainage) and infiltration pressure, force is required to move liquid in and out of the material pores [31]. Without mechanical loading the structure is reluctant to exchange fluid and facilitate the payload release.…”