Structural engineering of waterborne polyurethane for high performance waterproof coatings

A series of modified waterborne polyurethanes were synthesized using a self-emulsifying method for high performance waterproof coatings, such as fluoride polyurethane (FPU), siloxane modified waterborne polyurethane (SPU) and the polyurethane containing fluorine and siloxane (FSPU). The structures of waterborne polyurethane were designed from scratch, and the contents of fluoride acrylic monomer (FMA) and siloxane contents (HO-PDMS) segments in FSPU were adjusted for high performance waterproof. It's found that the sample has lowest water absorption, higher water contact angles, and better mechanical/thermal properties, when the FMA content is 20 wt% and HO-PDMS content is 3 wt%. The mechanisms of improvement of contact angles were investigated, due to the vinyl group crosslinking, higher temperature can significantly improve the hydrophobicity of the films in emulsion polymerization and film forming process. Optimized FSPU has a promising future as a kind of waterborne waterproof coatings.