Preparation of new superhydrophobic and highly oleophobic polyurethane coating with enhanced mechanical durability

In this study, a noble robust superhydrophobic and highly oleophobic polyurethane (PU)-SiO2 nanoparticle (NP) coating is specially designed using sol-gel process. For this purpose the effective parameters on surface tension and durability of the synthesized coating investigated and optimized. This new superhydrophobic and highly oleophobic coating exhibits good pensile hardness as high as 6H with adhesive force grade of 5B and repels water and oil with contact angles (CAs) of 159 degrees and 140 degrees respectively. The synthesized PU-SiO2 composite also retains an excellent amphiphobicity after a 7 days immersion in water with water and oil with CAs of 150 degrees and 130 degrees. Facile fabrication of PU-SiO2 coating with enhanced amphiphobicity and durability provides a novel pathway to the development of a high performance superamphiphobic surfaces. The outstanding properties of synthesized PU-SiO2 coating are mainly due to (i) reduction of surface energy by fluoroalkylsilanes, (ii) formation of hierarchical micro- and nanometer scale roughness structures on the coating surface, (iii) stable adhesion of SiO2 NPs into PU resin after cross-linking with isocyanate, and (iv) improving the chemical bonding and electrostatic interactions between film and substrate.