Textile Insight

Advanced Research Offers Coated Fabrics with Electromagnetic Pollution Protection. By Kathlyn Swantko s electronic devices become smaller, operate at faster speeds, and are used more often, electromagnetic interfer- ence (EMI) is escalating. A research team at Drexel University, led by Dr. Meikang Han, is addressing the issue by working to create a protective shield against the harmful EMI effects. The project utilizes MXene, a conductive two-dimensional coating material, discov- ered at Drexel in 2011. Fabrics coated with MXene have proven to be highly effective at blocking harmful electromagnetic waves and harmful radiation. Guided by Yury Gogotsi, Ph.D., Dept. of Materials Science & Engineering, and led by Simge Uzun, Ph.D. in Materials Science & Engineering, the current work focuses on developing a MXene-coated dip-dye textile process to create a protective fabric shield. "We reported on the excellent EMI shield- ing capability of MXene for the first time in 2016," explains Gogotsi. "Our first study in 2017 focused on developing conductive MXene-coated cotton and linen fibers/yarns (not fabrics) for textile-based devices. The ability to knit or weave these conductive MXene-coated yarns into complex geometries provided good design, flexibility, and versatil- ity, but proved to be too multifaceted and too expensive for many applications including smart garments." Advancing the MXene fiber/yarn research, the Drexel team began treating available woven cotton and linen fabrics through a dip-dye process, creating new shielding pro- tection. The team chose cotton and linen as base fabrics, because both are cellulose-based, hydrophilic, and can easily be infiltrated with solutions of 2D MXene flakes. Coating hydrophobic synthetic fabrics can also be used, however initial plasma treatments are required to prepare the fabric surface to ensure positive adhesion between the MXene flakes and the fibers. "Choosing the right substrate is crucial, not only for the end application, but also for processing the MXene dye," says Uzun. "By choosing hydrophilic cotton and linen fabrics, there was no need to modify the fabric with chemical or plasma treatments. Cotton and linen also possess a rough surface that provides the appropriate base for MXene flakes adherence." The fabric density is also an important factor in EMI shielding. The team opted for densely woven fabrics over knits. Wovens are typically less porous and stretchy, and when treated can better block radiation compared to knits. MXene Dip-Coating Process The dye used for the dip-coating process on cottons and linens consists of very small, nanometer-thin MXene particles dispersed in water. A low concentration of the negatively charged MXene dye (15 mg/ml) is used for the coating film, so the MXene flakes do not completely cover the fabric surface, therefore blocking further infiltration into the internal fabric structure. Drexel's research on this project provides an attractive alternative to current metal- based conductive dyes. MXene-coated fabrics provide a flexible, lightweight, and adaptable solution to protect devices and people with EMI shielding. Personal protective clothing, made with MXene-coated fabrics, can be used to limit radiation exposure for work wear and smart garments. The research creates a low-cost, lightweight, adaptable, wearable, and washable EMI-shielding textile for electromagnetic radiation protection. "The simple MXene dip-coating method enables an easy, scalable transfer of desirable protective MXene properties for conventional textile-based applications, including wallets, laptop cases, communication devices, and clothing," explains Gogotsi. l A EDUCATION | DREXEL UNIVERSITY New Age Textile Shield Kathlyn Swantko, president of the FabricLink Network, created www.TheTechnicalCenter.com for Industry networking and marketing of specialty textiles, and www.fabricklink.com for consumer education involving everything fabric. Contact: kgswantko@fabriclink.com textileinsight.com March/April 2021 ~ Textile Insight • 33 For more information on Drexel University's research on a "Textile Coating for Electromagnetic Protection", contact: Yury Gogotsi, Ph.D., Distinguished University and Bach Professor,Drexel University Department of Materials Science and Engineering at: yg36@drexel.edu, +1-267-230-8172, or SimgeUzun, Ph.D. in Materials Science & Engineering at: su63@dragons.drexel.edu

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