PDMS and POSS-dangling zwitterionic polyurethane coatings with enhanced anti-icing performance

Poly(sulfobetaine methacrylate) (PSBMA)-based zwitterionic polyurethane (ZPU), polydimethylsiloxane (PDMS)-dangling ZPU (PDMS-D + ZPU) and polyhedral oligomeric silsesquioxane (POSS)-dangling ZPU (POSS-D + ZPU) were prepared via atom transfer radical polymerization, quaternization reaction and crosslinking reaction to establish a superior anti-icing formulation. Obtained ZPU, PDMS-D + ZPU and POSS-D + ZPU coatings in contact with water all could support a self-lubricating water layer by the strong surface hydration and enrichment of zwitterionic PSBMA segments. In contrast, the PDMS-D + ZPU coating held the lowest amount of bound water due to the surface coverage of low-surface-tension PDMS chains, resulting in the lowest ice propagation rate. The POSS-D + ZPU coating held the highest amount of bound water because the aggregation of hard POSS particles on the surface induced more hydrophilic channels to enhance hydration of PSBMA. The hard POSS particles also served as a crystal nucleus to accelerate ice formation on the surface of POSS-D + ZPU coating. However, hydrophobic POSS allowed the POSS-D + ZPU coating to exhibit a lower ice propagation rate than ZPU coating. Additionally, both PDMS-D + ZPU and POSS-D + ZPU coatings were found to maintain low ice adhesion strength after multiple icing/de-icing cycles due to the synergism among the crosslinked structure, self-lubricating water layer and hydrophobic units.