为提高水性聚氨酯的疏水性和力学性能以扩大其应用范围，使用硅烷偶联剂 γ-甲基丙烯酰氧基丙基三甲氧基硅烷（KH570）、正硅酸四乙酯（TEOS）与疏水改性剂十六烷基三甲氧基硅烷（HDTMS）制备了表面带有双键和长链烷烃的疏水改性纳米 SiO₂分散液，然后加入支链上含硅氧烷的水性聚氨酯，（WPU）乳液原位合成了纳米 SiO2/聚氨酯光固化疏水涂层。考察了改性纳米 SiO₂含量对涂层性能的影响。结果表明：当改性纳米 SiO₂含量占复合涂料质量的 25%时，制备的涂层水接触角可达 117. 4°，24 h吸水率仅为 1. 1%，热分解温度提升了 50 ℃，同时具有良好的力学性能。

The aim of this paper was to improve the hydrophobicity and mechanicalproperties of waterborne polyurethane and expand its application range. Firstly，the dispersion of hydrophobic modified nano SiO₂ with double bonds and long-chain alkaneswas successfullyprepared using tetraethyl orthosilicate（TEOS），silane coupling agents γ -methacryloyloxy-propyltrimethoxysilane（KH570） and hydrophobic modifier hexadecyl trimethoxysilane（HDTMS）. Then，the prepared dispersion was directly added to waterborne polyurethane（WPU） lotion containing siloxane on the branch chain to in-situ synthesize the nano SiO₂/polyurethane UV curable hydrophobic coatings. The effect of modified nano SiO₂ content on the performance of nano SiO₂/polyurethane composite coatings was studied. The results showed that when themass fraction of modified nano SiO₂ in the total composite coating was 25%，the water contact angle of the prepared coating film could reach 117. 4 °，the 24-hour water absorption rate was only 1. 1%，the thermal decomposition temperature was increased by 50 ℃，and it also indicated good mechanical properties.