Novel waterborne polyurethanes containing long-chain alkanes: their synthesis and application to water repellency

In the fabric finishing field, the water repellents have received increasing interest in recent years and the development of a fluorine-free water repellent has become an attractive prospect. In this study, glyceryl monostearate-modified waterborne polyurethanes (GWPUs) with a branched structure act as water repellents, and were prepared from toluene diisocyanate, trimethylolpropane, hydroxypropyl polydimethylsiloxane, N-methyldiethanolamine, and glyceryl monostearate (GMS). The water repellency and other properties of GWPUs with different GMS content, such as water resistance, hydrophobicity, and air permeability, were studied. The results show that the GMS content for optimum water repellency was 20 wt%, which achieved the highest score (100 points) in a water repellency evaluation. As for the water repellent ability with a GMS content of 20 wt%, the water absorption of a piece of film was reduced to 7.80%, while the water contact angle of terylene coated by the water repellent rose to 148.0°.