In a sticky breakthrough, chemical engineers at the Indian Institute of Technology, Kanpur have come out with a remarkable reusable scotch tape that can be pasted at least 20 times without the adhesive losing its bonding strength.
The sticky coating mimics the toe pads of tree frogs and lizards that can stick to any surface for hours.
The research carried out by the trio — Animangshu Ghatak, Abhijit Majumder and Ashutosh Sharma-- – may lead to the development of reusable scotch tapes and clean adhesive which will not leave a smudgy impression on the surface after removal.
“Our experiments in the laboratory have shown that the adhesive can be used repeatedly at least 20 times without affecting its sticking quality. More experiments are required to find out the upper limit on the number of use,” Dr Ghatak told Deccan Herald.
The research has been published on Thursday in Science Express, online version of Science, one of the world’s most prestigious journals. The print journal will publish the findings on Friday.
When conventional adhesive tapes are pulled off, cracks spread through the adhesive away from the point where the tape is being detached. While it is possible to peel off the tape because of the cracks, they remain in the tape and are part of the reason it loses its stickiness.
But the tape created by the IIT team has microscopic channels inside the adhesive that help blunt the propagation of cracks and makes it a clean and reusable adhesive.
“While the adhesion film has a thickness of 100-800 microns, the dimension of the channels varies between 50 and 500 microns,” said Dr. Ghatak.
The process mimics the excellent adhesion shown by tree frogs or geckos. A large gecko can run across a ceiling and a tree frog can jump from branch to branch without falling so long as a single toe pad makes good contact with the tree. Also the detachment is effortless and the adhesives have self-cleaning properties.
The channels increased the elastic material's adhesion by roughly 30 times, by stopping crack formation and creating surface stresses due to capillary force.
Also, placing a layer of oil-filled channels of just the right diameter above a layer of air-filled channels allowed the adhesive to be easily released without losing its stickiness, the authors report.
“This adhesive can act as a quick release coating so that the tape, while sticking well, can be peeled off easily. The adhesive remains elastic and can thus be used again with no reduction in adhesive efficiency,” said Dr W Jon P Barne from the University of Glasgow.
Despite having commercial potential, the IIT team – because of their academic mindset – did not apply for a patent. “If I have a beautiful idea, I want to publish it first,” he said.
The researchers are aware how the post-it note inventor Arthur Fry and the manufacturing company 3M made millions from these ubiquitous canary-yellow sticking note slips.
