Adhesives

A new model predicts the force needed to peel a thin film off a surface.

FROM Scotch™ tape and cling wrap to the footpads that allow spiders and geckos to climb vertical walls, dry adhesives serve as removable joints between dissimilar materials. Adhesion is often determined by weak bonds (of the van der Waals type), and detachment is governed by the collective failure of such bonds. Researchers in Sweden have modelled the microscopic process of peeling off a thin film adhering to a surface with small bumps. The results show that tiny, random fluctuations in the bonds between the film and the surface can cause the film to peel off in a series of discrete steps, rather than in one continuous motion. The work has been published in the latest issue of the journal Physical Review Letters.

Compared with previous work, the new model could provide better estimates of the forces needed to detach thin films from surfaces. This would be particularly important for nanotechnology applications, helping scientists find optimal ways to peel away sheets of graphene and other substances in the laboratory.

R. Ramachandran