Biomimetic super slippery surface with excellent and durable anti-icing property for immovable heritage conservation

The formation and accumulation of ice on solid surface is not only a potential threat to our daily life, but also a hazard to cultural heritages, such as murals, grottoes, monuments, ancient buildings. Inspired by slippery inner surface of Nepenthes, slippery liquid-infused porous surfaces (SLIPSs) for anti-icing attract a lot of attention recently. In this work, dip-coating approach is utilized to create a hydrophobic silica layer grafted with long-chain organic molecules. After infusing the oil phase, a three-layer Nepenthes-like structure is formed. The SLIPS shows excellent anti-icing property. It reduces the ice-surface adhesion strength to 0 kPa on non-porous surface and 6.83 kPa on porous surface (sandstone from Yungang Grottoes) respectively. After 35 icing/de-icing cycles, the SLIPS still shows good anti-icing ability. Our results show that the middle long-chain organic layer not only enhances the surface hydrophobicity but also increases its affinity with the oil phase to reduce lubricating oil loss, thus increasing its anti-icing durability. When the anti-icing ability decreases with time, simple re-infusing the oil phase can easily restore the anti-icing performance to its original level. The SLIPSs prepared in this work show outstanding hydrophobicity, ice repellency, durability and satisfying water vapor permeability on treated porous sandstones, which makes it potential to protect immovable cultural heritages from ice hazard.