Chaotropic Ions Mediated Polymer Gelation for Thermal Management

Energy and environmental issues have increasingly garnered significant attention for sustainable development. Flexible and shape-stable phase change materials display great potential in regulation of environmental temperature for energy saving and human comfort. Here, inspired by the water absorption behavior of salt-tolerant animals and plants in salinity environment and the Hofmeister theory, highly stable phase change salogels (PCSGs) are fabricated through in situ polymerization of hydrophilic monomers in molten salt hydrates, which can serve multiple functions including thermal management patches, smart windows, and ice blocking coatings. The gelation principles of the polymer in high ion concentration solution are explored through the density functional theory simulation and verified the feasibility of four types of salt hydrates. The high concentration chaotropic ions strongly interacted with polymer chains and promoted the gelation at low polymer concentrations which derive highly-stable and ultra-moisturizing PCSGs with high latent heat (> 200 J g^-1). The synergistic adhesion and transparency switching abilities accompanied with phase transition enable their smart thermal management. The study resolves the melting leakage and thermal cycling stability of salt hydrates, and open an avenue to fabricate flexible PCM of low cost, high latent heat, and long-term durability for energy-saving, ice-blocking, and thermal management.