In this PhD research, model sports textiles are designed and fabricated as testbed to achieve dual-functionalities, i.e., good moisture transport property with low friction with skin or antibacterial property. To achieve the objectives, dual-layer textiles which consist of a thin hydrophobic electrospun inner layer and a thick hydrophilic electrospun outer layer are fabricated. In our hypotheses, 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 our design, the model textiles are fabricated by electrospinning, because the electrospun nanofibers have large specific surface area due to a lot of interpenetrating pores both inside and 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. Therefore, the electrospun nanofibrous mat is a perfect substrate to achieve good moisture transport property and dual-functions.
7.1.1 The enhancement of moisture transport property of the textile
The first hypothesis was that the moisture transport property of the textile could be improved by facilitating the capillary motion in the textile. According tothe mechanism of capillary motion, it could be facilitated by decreasing the pore size or increasing the surface hydrophilicity.
To validate the hypothesis and enhance the capillary motion in the textile, dual-layer mats composed of a thick layer of hydrophilic PAN nanofibers and a thin layer of hydrophobic PS nanofibers with and without interpenetrating nanopores are fabricated respectively. Then the mats are coated with PDOPA to different extents to tailor the water wettability of the PS layer. The water transport behavior of the mats is observed and compared.
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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. Thus the first hypothesis in the PhD. researches is validated.
7.1.2 The lower the friction between the skin and textile
The second hypothesis was that the good moisture transport property of the textile and the lower friction between the textile and skin could be achieved at the same time. Since the friction between the textile and the skin is also influenced by the hydration of the skin, the textile with good moisture transport property could provide a drier environment between skin and textile to lower the friction.
To validate the hypothesis, in our design, 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 PVDF-rich shell are fabricated by single-spinneret electrospinning and used as the inner layer of the dual-layer mats, and the moisture transport property and the coefficient of friction of the textile are measured. The results show that 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. Thus, the second hypothesis in the PhD. researches is validated.
7.1.3 The introduction of antibacterial property to the textile
The third hypothesis was that the good moisture transport property and antibacterial property of textile could be achieved at the same time by incorporation of antibacterial
Conclusions and future work Chapter 7
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nanoparticles agent, and the exposed nanoparticles have good anti-wash property due to their covalently attachment with the textile.
To validate the hypothesis, dual-layer nanofibrous nonwoven mats that composed of hydrophilic PAN outer layer and hydrophobic ethoxysilane-functionalized cross-linked PVDFinner layer were fabricated, and zinc oxide (ZnO) NPs were covalently attached on the surface of PVDF. According to results of related tests, the dual-layer mats have good moisture transport property, and the antibacterial property of the dual-layer mats rendered by the surface located and exposed ZnO NPs is also verified. The covalently bonded ZnO NPs show good anti-wash property, thus the potential health risk caused by the detachment of the NPs could be avoided. So, the third hypothesis in the PhD. researches is validated.
7.1.4 Overall conclusion
In my PhD study, the electrospinning-derived nanofibrous mats are used as model dual- layer sports textiles. The capillary motion in the mats is significantly facilitated by decreasing the pore size or increasing the surface hydrophilicity of the mats, and the water transport property of the mats are further enhanced by push-pull effect.Core-shell nanofibers with a PAN-rich core and a PVDF-rich shell as the inner layer could lower the friction between the textile and skin, at the same time keep good water transport property of the mats. Also, ZnO nanoparticles could be covalently introduced into dual-layer system as an effective and durable anti-bacterial agent. Thus, the hypotheses raised in chapter 1 are verified.