Synthesis and Characterization of Branched Polyurethane Synergistically Modified by Long‐Chain Alkyl and Silicone for Waterproof Textile Application

ABSTRACT To address concerns such as the biological toxicity of current fluorinated waterproofing agents and poor water resistance durability, a fluorine‐free, eco‐friendly waterproofing agent co‐modified with long‐chain alkane and silicone was developed. Using a mixture of toluene diisocyanate (TDI) and hexamethylene diisocyanate (HDI) as isocyanates, poly(tetramethylene glycol) (PTMG) and monoterminated‐α, α′‐biscarbinol poly(dimethyl siloxane) (PDMS) as mixed polyols, trimethylolpropane (TMP) as a branching unit, and long‐chain alkane 1‐hexadecanol (HA) as a capping agent, a series of solution‐based branched polyurethanes with varying PDMS contents were synthesized. These polymers were applied to polyester fabrics to investigate the effect of PDMS content on waterproof performance and durability. The results indicated that a polyurethane formulation with 30% long‐chain alkane capping content, 16% mass fraction of PDMS and 4.27% branching unit content exhibited optimal waterproof performance. After application onto polyester fabric, the treated fabric achieves a water repellency score of 85–90 and a static contact angle of 144.8° ± 0.5°. After 20 standard washes, the fabric's water contact angle remains above 135°, demonstrating excellent wash durability. Therefore, this research may provide some reference for the development of new waterproof functional textiles.