Simple water tunable polyurethane microsphere for super-hydrophobic dip-coating and oil-water separation

In this work, a simple thermally induced phase separation method with the assistance of little water dosage to prepare thermoplastic polyurethane (TPU) microsphere for super-hydrophobic dip-coating and its oil-water separation was developed. With the increasing of water content in TPU/dioxane solution, the cloud point temperatures of the ternary system sharply rose. Meanwhile, the TPU foam evolved to smooth non-hollow mi-crospheres and finally to nano-fibrous porous microspheres. More importantly, by controlling the water content, the microsphere surface can be controlled, forming various structures. The solution of microspheres could be used for the dip-coating of the nonwoven fabrics, and the dip-coated nonwoven fabrics shown super -hydrophobicity with a water contact angle of 153 degrees. The superhydrophobic dip-coated nonwoven fabric exhibited a good hot water, acid and alkali resistances. Additionally, it also exhibited high flux and oil-water separation efficiency.