Electrospinning-derived nanofibrous mats for dual-layer sports textile

Abstract

Properties of textiles have great influences on the thermo-physiological and skin sensorial wear comfort of the human body. Sportswear is expected to have good moisture management property, which is key factor to achieve wear comfort. For some sports, they are also expected to have low friction with skin and antibacterial capability. To meet these demands, single-layer fabrics are utterly incompetent. Thus, model dual-layer textiles that consist of a thin hydrophobic electrospun inner layer and a thick hydrophilic electrospun outer layer are designed and fabricated to verify the possibility to simultaneously achieve dual functionalities, including good moisture transport property, with low friction with skin or good antibacterial property. The hydrophobic inner layer ensures low water absorption and transmission of sweat via capillary motion, while the hydrophilic outer layer draws the sweat out from the inner layer and facilitates evaporation to the surrounding environment. In the PhD work presented in this thesis, electrospun nanofibrous mats are used as the model textiles because they have large specific surface area due to a lot of interpenetrating pores between the nanofibers, which could facilitate both the capillary motion and effect of surface modification and incorporation of functional materials. Also, to let the moisture transport away fast, fairly thin hydrophobic inner layers could be achieved by electrospinning because it could control the thickness accurately. To improve the moisture transport property, the capillary motion in the textile is facilitated by decreasing the pore size or increasing the surface hydrophilicity. Dual-layer mats composed of a thick layer of hydrophilic polyacrylonitrile (PAN) nanofibers and a thin layer of hydrophobic polystyrene (PS) nanofibers with and without interpenetrating nanopores are fabricated respectively. Then the mats are coated with polydopamine (PDOPA) to different extents to tailor the water wettability of the PS layer. It is found that with a large quantity of nanochannels, the porous PS nanofibers exhibit a stronger capillary effect than the solid PS nanofibers. The capillary motion in the porous PS nanofibers can be further enhanced by slight surface modification with PDOPA while retaining the large hydrophilicity difference between the two layers, inducing a strong push-pull effect to transport water from the PS to the PAN layer. To lower the friction between the textile and skin, both of the hydration of the skin and the chemical component of textiles are modified. Core-shell nanofibers with a PAN-rich core and a poly (vinylidene fluoride) (PVDF)-rich shell are fabricated by single-spinneret electrospinning and used as the inner layer of the dual-layer mats. The dual-layer textile has good moisture transport property and the inner layer of the textile has lower friction with the skin, because the PAN in the inner layer could increase the wettability of the layer, thus improve the capillary effect, and the PVDF-rich shell could lower the friction between the textile and the skin. The synergistic combination of a considerably hydrophobic PAN/PVDF inner layer and a highly hydrophilic CA outer layer induces a strong push-pull effect, resulting in efficient moisture-wicking. To introduce antibacterial property to the dual-layer textile, zinc oxide (ZnO) NPs were covalently attached on the surface of the ethoxysilane-functionalized cross-linked PVDF inner layer. The results of related testes show that the incorporation of the ZnO NPs could render the textile antibacterial property as well as enhance the water wettability of the inner, thus the moisture transport property of the textile is also strongly improved. Also, the ZnO NPs show very good anti-wash property due to the covalent bonding with the inner layer. Thus the potential health risk caused by the detachment of the NPs could be avoided. In summary, the research results presented in this thesis provide effective strategies to enhance the capillary motion and moisture transport property of the textile, as well as achieve dual functionalities. The design concepts demonstrated in this PhD research can be used as model systems for development of novel multifunctional textiles in industries.