Regulating hydration states in zwitterionic composite hydrogel coatings to suppress icing/frosting for enhancedthermal efficiency in heat exchangers

The formation of ice and frost on chilled surfaces operating in humid environments is a persistent challenge, particularly in heat exchangers where frost layers severely impede heat transfer and reduce overall energy efficiency. Although polymer gels have recently attracted considerable attention as anti-icing materials, conventional hydrogels often exhibit mechanical robustness issues and swell in humid environments. Achieving reliable anti-icing performance, therefore, requires materials capable of regulating interfacial water structure while maintaining stable behavior during continuous operation. This study proposes a silica–zwitterionic polymer hybrid gel that addresses both requirements through hydration-state confinement enabled by an inorganic–organic co-network. The hybrid gels are fabricated with various swelling ratios by tuning the composition ratios of silica and the zwitterionic polymer, 2-methacryloyloxyethyl phosphorylcholine (MPC), followed by a detailed characterization of water contents, quantification of icing and frost growth, and evaluation of thermal efficiency during repeated frosting–defrosting cycles. Incorporating silica nanoparticles into the MPC matrix yields a compact gel architecture with a substantially reduced free-water fraction, decreasing the swelling ratio to ~ 70%. This confined network enhances stiffness and increases the energy activation for ice formation by reducing the amount of free water. Consequently, the hybrid gel effectively suppresses ice nucleation, exhibiting ice-free performance for 60 min at − 10 °C and maintaining over 95% thermal efficiency over repeated cooling cycles. These findings demonstrate that the engineered inorganic–organic gel provides a thermally stable, high-performance anti-icing and anti-frosting platform, offering a promising strategy for improving thermal efficiency in practical thermal management.