Textile Insight

n ongoing collaborative effort involv- ing material scientists and engineers at the University of Virginia, Penn State, the University of Maryland, and the National Institute of Standards and Technology (NIST), has created an on-demand "switching effect" for thermal conductivity and mechanical prop- erties, which can be incorporated into textiles and garments. The biomimicry material at the center of this discovery is the protein used to build squid ring teeth, a spiky circle of biopoly- mer material found inside the suckers of the squid's tentacles. In the collaboration, the research with squid ring teeth pro- tein was broken down into three areas. The Penn State team created the squid ring teeth (SRT) polymer; the UVA team focused on characterizing the structural proteins and thermal engineering; and the UMD/NIST team concentrated on under- standing the underlying mechanism of the 'switching' effect. Professor Melik Demirel's group at Penn State has been working on squid ring teeth as a biomimetic material for almost a decade. Demirel has developed a material that mimics the responsive protein in squid ring teeth at the nano level, creat- ing a new sustainable polymer that can dynamically regulate thermal properties. Synthetic versions of the squid ring teeth proteins were developed with optimized properties for various applications. At UVA, the ExSiTE (Experiments and Simulations in Thermal Engineering) team under the direction of Patrick Hopkins, Mechanical & Aerospace Engineering Professor at UVA, initially collaborated with Demirel's group on analyzing the structure of the protein, and then jointly discovered the "thermal switching" phenomena. The research identified that the presence of water/moisture on the material creates an "on/ off" thermal switch — switching between insulating and cool- ing, based on the amount of water present. "We could not have progressed in our 'switching' research without Penn State's actual creation of the squid ring teeth, and without UMD's/NIST's efforts in understanding the under- lying mechanisms of the 'switching' effect," emphasizes John Tomko, a Ph.D. candidate in UVA's Department of Materials Science and Engineering and a leader in ExSiTE's 'switching' research. "Our joint endeavors have enabled our research into optimizing future thermal 'switching' effect materials." The Nanoscale Science of Thermal Switching Tomko describes how good a material will be as a heat conductor on a nanoscale level by comparing it to a "ball-and- spring" model, where the atoms (the ball) are bonded to each other with springs. The stronger the spring is, the more easily heat can move from one atom to another. Soft polymers, such as clothing materials, usually have low thermal conductivity and are poor conductors. Both their softness and thermal insu- lation are related to their weak bonds/springs. "This is exactly what we found in the protein-based materi- als. When the material is dry, atoms are more confined, and can not easily pass heat across the bond," explains Tomko. "On the other hand, when wet, the network of bonds open and conduct heat more readily. Similarly, when we design varia- tions of these materials with weaker bonds, we find that the thermal conductivity decreases, and the stiffness is reduced." EDUCATION | UNIVERSITY COLLABORATION Biomimicry is Key A Unique "Switching Effect" Shows Promise for Thermal Conductive Textiles. By Kathlyn Swantko Kathlyn Swantko, president of the FabricLink Network, created TheTechnicalCenter.com for Industry networking and marketing of specialty textiles, and FabricLink.com for consumer education involving everything fabric. A Thermal conductivity of squid-based biopolymer when wet and dry, measured over a number of cycles. The thermal image shows the cooling rate is increased when the material is exposed to water, but is more insulating when dry. For more information on UVA's research on "The Switching Effect Material for Thermal Conductive Textiles," contact John Tomko in UVA's Department of Materials Science and Engineering: jat6rs@virginia.edu 40 • Textile Insight ~ May/June 2019 textileinsight.com FabricLink.com TheTechnicalCenter.com "We have been using the FabricLink Network for over 10 years and it has consistently been one the top digital drivers to our site, and a great source of information for trade and consumers alike." Lisa Hardy North America Marketing Manager Teflon™ textile finishes, Teflon™ fabric protector, The Chemours Company Why clients are excited about the benefits of The FabricLink Network Partnership Opportunities: Kristi Rummel kristi@rummelmedia.com 608.435.6220 Editorial Opportunities: Kathy Swantko kgswantko@fabricklink.com 818.345.7501 How will they find you, if you're not there? The FabricLink Network THE Networking / Education Search Engine for ALL Things Textile Related! FL-TTC-TI-2016_Layout 1 2/24/16 7:55 AM Page 1

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