Chemical Engineering Researchers Create Textile That Imitates the “On-body Greenhouse Effect” of Polar Bear Fur
A team of researchers associated with the UMass Amherst Chemical Engineering (ChE) Department has designed a bilayer textile that successfully mimics the extreme adaptations of polar bears to the frigid temperatures of the most hostile environment on earth. Their groundbreaking research, published in the ACS Applied Materials and Interfaces, was performed by Associate Professor of Chemistry and ChE adjunct Trisha L. Andrew (senior author and principal investigator), lead author and ChE Ph.D. alumnus Wesley Viola, and ChE Ph.D. candidate Peiyao Zhao.
The pioneering research has attracted widespread media coverage, including stories in Time.News, The Limited Times, Sourcing Journal, Yahoo!Life, CTV News (Canada), SciTechDaily, Gizmodo, List 23, News Brig, ScienceDaily, New Atlas, Earth.com, and Engineering & Technology, all triggered by a UMass News Office release.
As the paper in ACS Applied Materials and Interfaces explains, “Humans use textiles to maintain thermal homeostasis amidst environmental extremes, but known textiles have limited thermal windows. There is evidence that polar-dwelling animals have evolved a different mechanism of thermoregulation by using optical polymer materials to achieve an ‘on-body greenhouse effect.’”
Part of the self-warming secret of polar bears is their white fur, which is extremely effective at conveying solar radiation toward the bears’ skin. “But the fur is only half the equation,” says Andrew. “The other half is the polar bears’ black skin.”
As Andrew explains it in the UMass News Office article, “Polar bear fur is essentially a natural fiberoptic, conducting sunlight down to the bears’ skin, which absorbs the light, heating the bear. But the fur is also exceptionally good at preventing the now-warmed skin from radiating out all that hard-won warmth. When the sun shines, it’s like having a thick blanket that warms itself up and then traps that warmth next to your skin.”
As a result of studying this example of maximum warmth in Nature, the three researchers are already applying their research with a company called Soliyarn, LLC, which was started by Andrew and produces a commercially available product called “PEDOT” that mimics the skin of a polar bear, while, as Zhao points out, a polypropylene top layer is the component that mimics the fur.
As the paper in ACS Applied Materials and Interfaces says, “Here, we design a bilayer textile to mimic these adaptations. Two ultralightweight fabrics with complementary optical functions, a polypropylene visible-transparent insulator and a nylon visible-absorber/infrared-reflector coated with a conjugated polymer, perform the same putative function as polar bear hair and skin, respectively.”
While retaining many desirable textile qualities, these layers maximize the absorption of sunlight and minimize the loss of body heat. Under moderate illumination, the revolutionary textile achieves a heating effect of plus 10 degrees Centigrade relative to a typical cotton T-shirt, which is 30 percent heavier.
The paper in ACS Applied Materials and Interfaces concludes that “Current approaches to personal radiative heating are limited to absorber/reflector layer optimization alone and fail to reproduce the thermoregulation afforded by the absorber/transmitter structure of polar animal pelts. With increasing pressures to adapt to a rapidly changing climate, our work leverages optical polymers to bridge this gap and evolve the basic function of textiles.”
Viola, who completed his Ph.D. in Chemical Engineering at UMass and is now the senior R&D engineer at Soliyarn, observes that “Space heating consumes huge amounts of energy that is mostly fossil-fuel-derived. While our textile really shines as outerwear on sunny days, the light-heat trapping structure works efficiently enough to imagine using existing indoor lighting to directly heat the body. By focusing energy resources on the ‘personal climate’ around the body, this approach could be far more sustainable than the status quo.”
The research, which was supported by the National Science Foundation, is already being applied, and Soliyarn has begun the production of PEDOT-coated cloth. (April 2023)