Double-solvent phase change hydrogels with light scattering and shape memory for thermal management

Polyethylene glycol (PEG) has excellent thermal storage capacity, but there are still problems of easy leakage and poor stability in its practical application. In this study, phase change hydrogel was rapidly prepared by UV irradiation curing using water (H 2 O) and PEG as double-solvent, with acrylamide (AM) and hydroxyethyl acrylate (HEA) as copolymerized monomers, denoted as P(AM-co-HEA)/PEG phase change hydrogel (PPCH). The experimental results show that PPCH possesses excellent flexibility and thermal stability. Moreover, due to the light scattering effect triggered by the thermal motion of its internal PEG molecular chains, PPCH exhibits reversible optical transition between translucent and opaque states. More importantly, based on the formation of dynamic hydrogen bonding cross-linking mechanism between P(AM-co-HEA) and PEG, PPCH possesses thermo-responsive shape memory due to the stretching and slipping of molecular chain segments before and after the PEG phase change. In addition, the dynamic hydrogen bonding cross-linking mechanism is regulated by the PEG phase change, and PPCH also possesses high elongation at break. Notably, PPCH is also able to maintain the working temperature below the safety threshold under the high-speed charging/discharging conditions of lithium batteries, showing excellent thermal regulation performance and further proving its wide application potential.