Anti-icing propylene-glycol materials

Liquid propylene-glycol (PG) has long been used as an anti-icing substance, for example, by spraying on an airplane parked in an airport. In applications, large quantities of PG flow away, which is costly and raises environmental concerns. Here we report propylene-glycol materials, including PG-gels and PG-gel/cotton composites. A PG-gel consists of PG molecules as a solvent and a polymer network. PG evaporates slowly, and the polymer network retains the PG molecules so long as the gel is not in contact with running water. Water and PG form a eutectic system with an eutectic temperature of −60 °C. When ice falls on the surface of the gel, the ice and the PG molecules compete for water molecules, and thermodynamics dictates that the ice should lose water molecules to the PG molecules, so that ice melts and water molecules dissolve in the gel. A liquid-like layer exists on the ice/gel interface, the adhesion energy between the gel and ice is low, and ice readily slides on the gel. We peel a PG-gel from ice, and measure a low adhesion energy of ∼3 Jm−2 at temperatures about −35 °C. We further demonstrate PG-gel/cotton composites as tough, anti-icing blankets. The blankets are reusable if one removes water by dehydration, and replenish PG by submerging the blanket in liquid PG.