A Coating That Fights Ice

Preventing the thick, icy buildup that accompanies freezing rain could become as simple as applying a coating. The first anti-icing superhydrophobic coating has been developed by the University of Pittsburgh’s Di Gao and coworkers. The coating is composed of a composite of acrylic polymer and silica nanoparticles (Langmuir, DOI: 10.1021/la902882b). The nanoparticles provide the coating with roughness that repels water in the same manner as lotus leaves. While particles that are 1 μm in diameter or smaller will render the coating superhydrophobic, the particles must be 50 nm across or smaller for the coating to be anti-icing. “The energy barrier for the heterogeneous nucleation process increases significantly as the particle size decreases,” Gao explains. “Therefore, the surfaces with smaller particles possess a larger energy barrier for the nucleation process, and therefore icing will be less likely to occur.” Gao’s team demonstrated the coating’s ice-repellent properties by applying it to portions of an aluminum plate and satellite dish antenna prior to a freezing rainstorm. Whereas the uncoated portions were covered in a thick, icy glaze after the storm, the areas that were coated remained ice-free.