Hydrophobic Modification of TPU Films for Use in Storm-resistant Fabrics

Waterproof moisture-permeable films with excellent water resistance and breathability are employed in functional clothing to improve the comfort of wearers. Although polytetrafluoroethylene microporous membranes exhibit outstanding water resistance and moisture permeability, their application is limited because of the environmental impact of fluorinated compounds. For this reason, herein, we aimed to improve the hydrophobicity of thermoplastic polyurethane (TPU) microporous membranes while maintaining their moisture permeability. We employed silane coupling agents to modify nanosilica particles, which were then coated on TPU microporous membranes to enhance their waterproof performance. The optimized parameters for the modification process of silica nanoparticles are γ-aminopropyltriethoxysilane and hexadecyltrimethoxysilane (silane coupling agents) concentrations of 8% relative to the mass of silica, a modification time of 2 h, and a temperature of 70°C. The water contact angle of the particles modified under these conditions reached 138.58°. The modified SiO 2 particles were used to treat the TPU film, with an optimal mass fraction of the modified silica of 3% and a modification time of 4 h. The water vapor transmission of the modified TPU film was 5661.92 g/(m 2 ·24 h), with enhanced hydrophobicity, and its water absorption rate was 12.41%, which is 16.49% lower than before modification. Additionally, under simulated heavy rain conditions, the water absorption rate of the composite fabric with modified TPU film was lower by 14.7% than that of the composite fabric with unmodified film.