Tuning the thermoregulatory and tensile performance of electrospun hydrophobic microfibers through a low-cost water doping method

Waterproof fabrics, especially those consisting of hydrophobic microfibers, could protect human from severe weather conditions and environments, and thus are wildly used in sportswear, outdoor products, medicinal, and skin care. However, conventional electrospun hydrophobic microfibers usually lack thermoregulatory functions to provide more comfortable environments, and existing techniques to achieve thermoregulation require delicate fabrications and usually reduce their mechanical performance. Therefore, in this paper, we develop a low-cost water doping method to tune the thermoregulatory and tensile performance of electrospun hydrophobic microfibers. Through an emulsification and subsequent emulsion-electrospinning process, water in PMMA microfibers with 25-45 μm large diameter (W/P-L) and that with 2.5-4 μm small diameter (W/P-S) are fabricated to study the effect of water addition. The water, which exhibit high specific heat capacity, improves the material's heat storage capacity. Additionally, the water in hydrophobic microfibers facilitates the formation of a solid-vapor-liquid double interface, thus augmenting the insulating capacity of fibrous membranes and enhancing their thermoregulatory performance. The integration between soft and rigid materials improves the tensile performance of microfibers. Owing to the reliable encapsulation, our water doping method not only enables the fibrous membranes possessing better thermoregulatory and mechanical properties but also retains the excellent water repellency ability of microfiber architecture, thus broadening the potentiality of electrospun fibrous membranes when used as materials for waterproof sportswear, and other outdoor products.