Liquids with High Compressibility

• Published in: Advanced materials (Weinheim) 2023-11, Vol.35 (44), p.e2306521-n/a
• Main Authors: Lai, Beibei, Liu, Siyuan, Cahir, John, Sun, Yueting, Yin, Haixia, Youngs, Tristan, Tan, Jin‐Chong, Fonrouge, Sergio F., Pópolo, Mario G. Del, Borioni, José L., Crawford, Deborah E., Alexander, Francesca M., Li, Chunchun, Bell, Steven E. J., Murrer, Barry, James, Stuart L.
• Format: Article
• Language: English
• Subjects: compressible liquids; Fluid flow; Hydraulics; Hydrophobicity; Incompressible flow; Liquids; Materials science; neutron scattering; Pneumatics; porous liquids; Shock waves; Sound propagation; Water chemistry; Water compressibility; ZIF
• ISSN: 0935-9648; 1521-4095
• DOI: 10.1002/adma.202306521

Compressibility is a fundamental property of all materials. For fluids, that is, gases and liquids, compressibility forms the basis of technologies such as pneumatics and hydraulics and determines basic phenomena such as the propagation of sound and shock waves. In contrast to gases, liquids are almost incompressible. If the compressibility of liquids could be increased and controlled, new applications in hydraulics and shock absorption could result. Here, it is shown that dispersing hydrophobic porous particles into water gives aqueous suspensions with much greater compressibilities than any normal liquids such as water (specifically, up to 20 times greater over certain pressure ranges). The increased compressibility results from water molecules being forced into the hydrophobic pores of the particles under applied pressure. The degree of compression can be controlled by varying the amount of porous particles added. Also, the pressure range of compression can be reduced by adding methanol or increased by adding salt. In all cases, the liquids expand back to their original volume when the applied pressure is released. The approach shown here is simple and economical and could potentially be scaled up to give large amounts of highly compressible liquids. Conventional liquids are barely compressible. However, here, a simple strategy is presented to increase the compressibility of aqueous liquids by dispersing into them small particles of porous materials with empty hydrophobic pores. The total compression is due to compression of the interparticle water phase in addition to water being forced into the pores, and the resulting compressibility is up to 20 times that of conventional liquids.