14 DAY TRIAL // When stickers, for instance, are taped to windows or doors, they eventually form blisters. Sunlight hitting them directly also deforms and distorts their colors, until they eventually fall off. While strolling through the corridors of the Edgerton Center, in Building 4 at the Massachusetts Institute of Technology (MIT), Department of Mathematics instructor Pedro Reis noticed the bending plastics, and found the phenomenon interesting. The ensuing research may offer new hints on how to construct stretchable and bendable electronics, Technology Review informs.
“It's something that's around you all the time – but if you look at it [in] a different way you can see something new,” Reis says of an MIT logo that he saw slowly peeling away from a glass door. Together with scientists from the French National Center for Scientific Research, the mathematics instructor analyzed heat-induced blistering and peeling, a process known as delamination, which mostly occurs at the contact zone between a thin film and the surface to which it is attached (such as stickers on glass). In addition to the heat, the team already knew that another factor that triggered delamination was related to whether the surface on which the film was attached was compressed.
When this happens, they say, the film bends as much as its elasticity coefficient allows it to, until the compressing force becomes too large, causing the sticker or another thin film to simply pop away. This is perceived on the outside as a new blister. Puzzled by this process, the team started conducting a series of experiments using compression forces and thin films, in order to determine the exact factors that caused popping and blisters implicitly.
They note that a large number of triggers is responsible for delamination in such situations. The experts mention the elasticity of the film, the elasticity of the surface, and the strength of the adhesive between them as the most important ones. The researchers now hope to be able to use a slow and well-controlled delamination process to rearrange the wiring patterns inside future bendable electronics, which have thus far been plagued by breaking problems within them.