Reusable Adhesive

Breakthrough Innovation: Reusable Adhesive That Works Underwater Researchers from the University of Illinois have introduced an advanced-technology, reusable adhesive type. They developed an adhesive that activates within seconds, works underwater, and is strong enough to support 11 pounds (approximately 5 kg) of weight—shape-memory polymers (SMPs). A team consisting of associate professor Seok Kim from the Department of Mechanical Science and Engineering, graduate student Jun Kyu Park, and former graduate student Jeffrey D. Eisenhaure (who completed his doctorate in Mechanical Engineering in 2017 and currently works at Northrop Grumman) demonstrated that SMPs retain their dry adhesive properties even when submerged in water. Their joint paper "Reversible underwater dry adhesion of a shape-memory polymer" was recently published in the scientific journal Advanced Materials Interfaces. Classified as smart materials, SMPs have the ability to transition manually from their original form to a deformed state. Kim and his team manipulated the chemical composition of their SMPs to enable them to provide strong surface adhesion when submerged in liquids such as water and oil. Kim stated: "Dry adhesives produced by drawing inspiration from gecko feet are considered insufficient for achieving high-level adhesion on wet or water-submerged surfaces. However, with our reversible dry adhesive SMPs, the opposite of this view has been proven." By applying pressure to the SMP in its original, rubber-like state when submerged in water, the liquid contact within it can be expelled from the interface. Under sufficient pressure, the SMP transitions to a glassy state and provides a very strong dry adhesion level, creating an air-tight contact condition. However, this condition is temporary, and the SMP's shape-retention properties allow the adhesion to be reversed. Moreover, because the SMP transitions smoothly between the two states, its adhesiveness is reusable. The researchers measured the maximum adhesion strength of the SMP when submerged in freshwater at 18 atm, meaning this is at least 18 times greater than the strength of vacuum suction cups. Similar results were obtained when the SMPs were submerged in saltwater and oil. The researchers conducted various experiments to explore potential applications for their SMPs. In one of these experiments, they used the developed adhesive to attach a hook to a wet wall. Once the SMP adhesive set, they hung a backpack filled with items on the hook and observed no weakening in the adhesion. Kim, who plans to commercialize the findings through a start-up, concluded: "These findings will result in reusable high-strength adhesives for installations on wet or underwater surfaces. The next step for this technology will be to examine SMP adhesive systems in greater detail to enable reversible, adhesive fixed-holding devices."

Source

Story Source: Materials provided by University of Illinois College of Engineering. Note: Content may be edited for style and length. University of Illinois College of Engineering. "Groundbreaking new reusable adhesive works underwater." ScienceDaily. www.sciencedaily.com/releases/2019/01/190128122244.htm (accessed October 2, 2022). / https://www.sciencedaily.com/releases/2019/01/190128122244.htm