In the future, you may be able to thank a squid for keeping your coffee hot on a cold day. Engineers at the University of California, Irvine developed an adaptive composite material inspired by cephalopod skin that can insulate beverage cups, restaurant to-go bags, parcel boxes, and even shipping containers.
The breakthrough is an infrared-reflecting metallized polymer film created in the laboratory of Alon Gorodetsky, an associate professor of chemical and biomolecular engineering at UC Irvine. Gorodetsky and his colleagues describe a large-area composite material that regulates heat through the use of reconfigurable metal structures that can reversibly separate from one another and reassemble under different strain levels.
“The metal islands in our composite material are adjacent when the material is relaxed and separate when it is stretched, allowing for precise control of infrared light reflection and transmission or heat dissipation,” Gorodetsky explained. “The mechanism is analogous to the expansion and contraction of chromatophores in the skin of a squid, which alters visible light reflection and transmission.”
Chromatophore size variations aid squids in communicating and camouflaging their bodies in order to evade predators and conceal themselves from prey. Gorodetsky explained that by adopting this approach, his team enabled “tuneable thermoregulation” in their material, which could result in increased energy efficiency and protection of sensitive fingers from hot surfaces.
A significant accomplishment of this project was the development by UCI researchers of a cost-effective method for producing their composite material in application-relevant quantities. According to the paper, the raw materials for copper and rubber start at about a dime per square metre and are further reduced through economies of scale. The team’s fabrication technique involves depositing a copper film onto a reusable substrate such as aluminium foil and then spraying multiple polymer layers onto the copper film in virtually any batch size imaginable.
“The integrated manufacturing strategy that we have now perfected in our laboratory is a true game changer,” Gorodetsky explained. “We’ve been experimenting with adaptive materials and systems inspired by cephalopods for years but have previously been limited to fabricating them over relatively small areas. Now, there is finally a way to manufacture this material in a factory on a roll-by-roll basis.”
The developed strategy and economies of scale should enable the composite material to be used in a wide variety of applications, ranging from coffee cup cosy to tents, or in any container requiring adjustable temperature regulation.
The invention is environmentally friendly due to its sustainability, according to lead author Mohsin Badshah, a former postdoctoral scholar in chemical and biomolecular engineering at UC Irvine. “Bulk recycling of the composite material is possible by removing the copper with vinegar and repurposing the remaining stretchable polymer,” he explained.