Reversible thermo-responsive transitions between aerogel-based porous liquids and solid-liquid-vapor triple-state gels

• Published in: Journal of materials chemistry. A, Materials for energy and sustainability Materials for energy and sustainability, 2024-06, Vol.12 (24), p.14659-14668
• Main Authors: Li, Leqin, Wu, Miaojiang, Yao, Sa, Hou, Yinglai, Yuan, Ruizhe, Liao, Jianhe, Zhang, Xuetong
• Format: Article
• Language: English
• Subjects: Aqueous solutions; Gels; Heat treatment; Hydrophobicity; Liquids; Microparticles; Polymers; Porosity; Porous materials; Silica; Silica aerogels; Thermal conductivity; Vapors
• ISSN: 2050-7488; 2050-7496
• DOI: 10.1039/d4ta02365j

Porous liquids (PLs), porous materials with flowable states, show promising applications in some emerging fields. However, creating porous materials with on-demand flowability is still significantly challenging. Herein, aerogel-based stimulus-responsive porous liquids have been proposed and fabricated via dispersing superhydrophobic silica aerogel microparticles in a polymer aqueous solution with either lower or upper critical solution temperature (LCST or UCST), respectively. The resulting aerogel-based intelligent porous liquids possess quite low density (0.56 g cm −3 ), high porosity (up to 48.57%), low thermal conductivity (0.239 W m −1 K −1 ) and appropriate viscosity (4.1-220.6 Pa s). Most importantly, the resulting porous liquids show reversible thermal responsiveness. Thus, a new condensed state, i.e. , solid-liquid-vapor triple-state gels, might be obtained via on-demand thermal triggering of these aerogel-based porous liquids. Cut triple-state gels show interesting self-healing behaviors via either thermal treatment or replenishment of a small extra amount of porous liquids. To our surprise, the reversible transition between aerogel-based flowable porous liquids and solid-liquid-vapor triple-state non-flowable gels has endowed these materials with plastic-like processing capability upon demand. These porous liquids, together with those triple-state gels, might find broad applications in some emerging fields, and the work reported here might inspire scientists to fabricate more aerogel-based porous liquids and triple-state gels. Reversible plastic-like processing between novel aerogel-based porous liquids and solid-liquid-vapor triple-sate gels with self-healing behavior has been achieved by thermal stimulation.