Super-elastic smart phase change material (SPCM) for thermal energy storage

Abstract

Super-elastic phase change materials (SPCMs), as brand-novel smart materials, have a wide range of potential applications in stress induction, thermal energy storage and temperature control. Polyacrylamide-based HAH@PEG_12h SPCMs with an ultimate tensile ratio greater than 500% were synthesized for the first time by a popular molecular self-assembly technology. In-situ polymerized polyacrylamide (PAM) builds a reversible deformable three-dimensional network, while the filled PEG2000 PCMs form hydrogen bonds with its amino group (–NH2). 260% tensile ratio is impossible to cause obvious liquid leakage for the HAH@PEG2000 form-stable phase change material, even exceeding the melting temperature of the PEG2000 PCM. Reversible PAM–NH2⋯O–PEG hydrogen bond can also reduce the sensitivity of the polyacrylamide-based hydrophobically associated hydrogel (HAH) to air humidity fluctuations. Volumetric deformation ratio of the as-prepared PCM gel is close to zero during water vapour adsorption/desorption, which is much lower than that of the HAH without PEG2000 (20 vol%). Water molecules entering the self-prepared SPCMs are preferentially adsorbed by the PAM 3D architecture, which significantly improves the anti-interference ability of the PEG PCMs. The outstanding comprehensive performance makes the HAH@PEGs SPCMs have great potential in the future.