Preparation of super-hydrophobic films based on waterborne polyurethane and their hydrophobicity characteristics

Super-hydrophobic films are applied in various antifouling materials such as ship and car due to their extreme water resistance. Herein, we designed and fabricated superhydrophobic waterborne fluorinated polyurethanes films containing guanidine group (WFPUs films) via one-step spray method. It was found that the guanidine and carbonyl groups of WFPUs films rapidly cross-linked by hydrogen bonds obtaining the superhydrophobic WFPUs films with appropriate surface roughness. When the amount of guanidine salt chain extender reached 11%, the water contact angle (CA) and sliding angles (SA) of WFPU4 film were 153.82° and 4.2° ± 0.9°, respectively. The surface energy was also found as <10 mJ/m2. The Ra (surface roughness) value of WFPUs films reduced from 26.3 nm to 5.4 nm. Moreover, upon modified with guanidine group, superhydrophobic WFPU4 film performed the mechanical durability, and the hydrophobicity of cotton was effectively enhanced. And these super-hydrophobic films containing guanidine group have potential applications in the field of environmentally friendly coatings.