关键词: 超疏水, 超临界CO₂, 涂层, RESS法, 水性聚氨酯

Abstract: The SiO₂/PU superhydrophobic coatings were prepared by using rapid expansion of supercritical CO₂.Firstly, by modifying nano-silica with thirteen fluoride octyltriethoxysilane(F-silane)andγ-(methacryloyloxy-oxy)propyl trimethoxysilane (KH-570), nano-silica particles containing double bonds were prepared and then were dispersed in supercritical CO₂.At the same time, a polyurethane coating containing double bond and an initiator was prepared.Subsequently, the nano-silica particles were injected onto the polyurethane coating surface making use of rapid expansion of supercritical CO₂, and then were dried by heating to form a stable rough structure because of the nano-silica particles being grafted on the polyurethane coating.This way, a SiO₂/PU film with superhydrophobic surface was obtained.Moreover, the effect of nozzle temperature, reaction kettle temperature and pressure, ratio of coupling on coating hydrophobicity and surface roughness were studied.The results showed that the static water contact angle of the coating could be up to 169.1°±0.6°.When the temperature of the nozzle and the reaction kettle were all 90℃, the reaction kettle pressure was 16 MPa and ratio of F-silane to KH-570 was 1∶1, the surface roughness was 7.3 μm, the obtained film had good super-hydrophobicity, and had excellent scratch resistance.In addition, the superhydrophobic coating had good performance and was environmental, and also could be produced cost-effectively on a large scale.

Key words: superhydrophobic, supercritical CO₂, coating, RESS, water-based polyurethane