Effects of fluorosilane addition on polyurethane electrospun membranes with waterproof and breathable performance

Waterproof and breathable fibrous membrane is a new type of polymer functional material widely used in outdoor protection, sports equipment, industrial production, and other fields. To impart waterproof ability and breathability, a common practice is to modify the electrospun membrane with low surface-energy materials, such as fluorosilane. However, when directly added to the electrospinning solution, the effects of fluorosilane on the property of the prepared membrane have been scarcely reported. Herein, we prepared the electrospun polyurethane membrane by adding two types of fluorosilane into the polyurethane solution. The effects of fluorosilane type and concentration on the conductivity and viscosity of the electrospinning solution were investigated. Moreover, the prepared polyurethane/fluorosilane fibrous membranes are analyzed in terms of their surface morphology, structure, water contact angle, breathable performance, and mechanical properties. Results show that the dual effects of fluorosilane content exert an opposing influence on the jet drawing process, which yields a minimum fiber diameter when the fluorosilane content is 20%. Under this condition, the membrane shows the highest water vapor transmission rate (10.4 kg/(m2·d). In addition the membranes have the maximum water contact angle (138°) and breaking strength (12 MPa) when the fluorosilane content is 40%. This study provides insights into fabricating electrospun waterproof and breathable membranes in equipment for outdoor sports and protection.