Lubricated PDMS-bearing ladderlike polysilsesquioxane coating: Fabrication and factors governing its long-term ice-shedding performance

Reacting an epoxy-bearing ladder-like polysilsesquioxane (LASQ) with mono-carboxy-terminated poly(dimethyl siloxane) (PDMS-COOH) yields LASQ-PDMS, a blend of LASQ and a graft (g) copolymer LASQ-g-PDMS. Photolyzing a cast film of LASQ-PDMS containing a cationic ring-opening polymerization initiator produces a robust and wear-resistant coating. Such a coating presents a liquid-like surface PDMS brush layer that imparts anti-smudge and ice-shedding properties. These properties are significantly enhanced via the application of a silicone oil (SO) as a lubricant. Investigated in this study are the effects of changing the molecular weight and mass fraction of PDMS as well as the molecular weight of a SO or composition of a SO mixture on properties of the lubricated LASQ-PDMS coating. These properties include the coating's hardness, water repellence, wear resistance, SO retainability, initial ice adhesion strength (τ), variation of τ with the number of abrasions made by steel wool on a coating, and variation of τ with the number of icing/de-icing cycles. This systematic study establishes the exceptional wear resistance of the LASQ-PDMS coatings and reveals SO retainability as the primary factor governing the long-term ice-shedding performance of the coatings.