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A new kind of meniscus instability leading to the formation of stationary fingers with a well-defined spacing has been observed in experiments with elastomeric films confined between a plane rigid glass and a thin curved glass plate. The wavelength of the instability increases linearly with the thickness of the confined film, but it is remarkably insensitive to the compliance and the energetics of the system. However, lateral amplitude (length) of the fingers depends on the compliance of the system and on the radius of curvature of the glass plate. A simple linear stability analysis is used to explain the underlying physics and the key observed features of the instability.

Inspired by the observation that many naturally occurring adhesives arise as textured thin films, we consider the displacement controlled peeling of a flexible plate from an incision-patterned thin adhesive elastic layer. We find that crack initiation from an incision on the film occurs at a load much higher than that required to propagate it on a smooth adhesive surface; multiple incisions thus cause the crack to propagate intermittently. Microscopically, this mode of crack initiation and propagation in geometrically confined thin adhesive films is related to the nucleation of cavitation bubbles behind the incision which must grow and coalesce before a viable crack propagates. Our theoretical analysis allows us to rationalize these experimental observations qualitatively and quantitatively and suggests a simple design criterion for increasing the interfacial fracture toughness of adhesive films.

Adhesion between solid materials results from intermolecular interactions. The fracture resistance of an adhesive joint is, however, determined jointly by the mechanical deformation in the bulk material and the strength of the interfacial bond. The force needed to break an interfacial bond does not have a fixed value; it depends on the thermal state of the system and the rate at which the force is transmitted to the bond. The concomitant energy dissipation arising from the extension and the relaxation of the interfacial bonds contributes a significant resistance to fracture, which is clearly evident in elastomeric polymers. This issue of interfacial dissipation and its relationship to the length of the interfacial bridges and the rate of crack propagation are addressed with the kinetic theory of bond rupture in the tradition of the models developed by Eyring, Tobolsky, Zhurkov, Bueche, Schallamach, Kausch, and more recently, by Evans and Ritchie. Next, the method is extended to address the velocity-dependent sliding friction of elastomers against low energy solid surfaces. The theme of this article is to point out that certain aspects of adhesion, friction, and fracture may be described under a generalized framework of interfacial kinetics.