Preparation and properties of fluorinated silicon two‐component polyurethane hydrophobic coatings

A polyurethane (PU) hydrophobic coating was prepared by the two‐component method, polycarbonate diol and isophorone diisocyanate becoming a two‐phase composition. The PU films with hydrophobic surface were prepared by establishing a rough structure on the surface of silica (SiO 2 ) modified with silane coupling agents (γ‐(2,3‐epoxypropoxy)propytrimethoxysilane (KH560) and (heptadecafluoro‐1,1,2,2‐tetradecyl)trimethoxysilane (FAS)). First, the surface of SiO 2 was covered by a layer of hydrophobic methyl and fluorocarbon (C–F) groups. Then, the SiO 2 and modified SiO 2 were obtained by the introduction of KH560 and FAS with the silanol reaction by ultrasonic stirring. The effect of SiO 2 and modified SiO 2 on the structure and hydrophobic properties of PU was investigated by a series of test instruments. The results showed that the introduction of SiO 2 and modified SiO 2 was beneficial for increasing the roughness of the PU coating surface; the roughness of FAS/SiO 2 ‐PU could reach up to 14.790 nm, four times better than pure PU. A hydrophobic modified PU coating with water contact angle 123° was fabricated by using the hydrophobic C–F group FAS as a low surface energy material and establishing a micro rough structure on the surface of PU. Moreover, PU modified with KH560 and FAS can reduce the glass transition temperature ( T g ) of soft segments, resulting in improvement of micro‐phase separation. © 2020 Society of Chemical Industry