Fabrication of superhydrophilic wool fabrics by nanotechnology

Abstract

Because of the fatty layer on its surface, wool fiber is hydrophobic, which results in poor water absorption and wicking properties that affect the comfort of wool textiles. The purpose of this research is to improve the wettability and comfort of wool textiles using nanotechnology. To reveal the knowledge gaps and ensure the originality of this study, a critical review of literature was conducted in relevant areas, including existing methods. To achieve the objectives of the research, a simple method for fabricating environmentally stable superhydrophilic wool fabrics was developed. Silica sols with diameters of about 27 nm were prepared by a modified Bechtold-Snyders method and then coated on the surface of pristine wool fibers to form an ultrathin layer, increasing both the surface roughness and energy of the wool fabrics. The morphology and composition of silica-sol-coated wool fabrics were characterized by a combination of SEM, TEM, EDX, FTIR, and XPS measurements. The wettability of the fabric was measured in terms of the water contact angle and the rate of water absorption. After evaluating the washing fastness of the superhydrophilic wool fabrics in perchlorethylene and water, it was found that the durability of the silica sols coated wool fabrics needed to be improved. To achieve fast absorbing and quick drying wool fabrics with good washing durability, reactive siloxane monolayer was functionalized on inherent hydrophobic wool fiber surface, and an ultrathin silica nanoparticles layer was grafted on the surface by in-situ growth method. The possible formation mechanism of superhydrophilic silica layer on the wool fibers surface was discussed and further identified by Fourier transform infrared and X-ray photoelectron spectroscopy measurements. To evaluate the wettability change of the silica grafted wool fabric, in addition to the contact angle, in-depth characterizations of water absorbing and drying properties of wool fabrics were measured using both static and dynamic methods (Chinese National Standard GB/T 21655.1-2008 and GB/T 21655.2-2009). According to the test standard, the prepared silica grafted wool fabric has excellent water absorption and quick drying properties that can be maintained after washing 20 times in a washing machine. Because of the strong immobilization through siloxane bonding and in-situ growth, this strategy was extended to durable multifunctional wool fabrics combined with superhydrophilic, self-cleaning, and antibacterial properties. To study the relationships between functional properties, nano scale sizes, and morphology of the wool textile materials, silica nanoparticles of 50, 150, and 300 nm were fabricated via a modified stober reaction and coated on the surface wool fabric. The wettability of wool fabric modified with the silica nanoparticles depended on both surface energy and structures, such as roughness and porosity. In summary, this work focuses on the fundamental and universal need of the wearer-comfort. Nanotechnology has shown great potential to provide comfortable and functional wool fabric.