Adhesion of Polymers

Abstract

The adhesion of a polymer to itself, to a different polymer, or to an inorganic material can often be one of its most important properties. Adhesives are normally polymers, but then so are nonstick coatings. Clearly, polymer adhesion can vary from very strong to extremely weak. Adhesion is a sufficiently complex and broad area that there are a range of approaches to its understanding. My approach here is one that attempts to bridge between the mechanics of crack propagation and the atomic-scale processes that occur at a crack tip. I will not be concerned with the details of the interface chemistry and its modification. The interface chemical approach is very useful in many practical situations but is often very specific to particular systems. Adhesion (or perhaps its inverse) can be considered a failure property. We can only measure the adhesion between two items by breaking the joint between them. I will be mainly concerned with failure by crack propagation using a fracture-mechanics approach.I will first consider the general question of the effects of bulk mechanical properties on adhesion and then describe some recent work on fracture mechanics of biomaterial interfaces as it relates to polymer glasses. I will then change the focus to the scale of the polymer chain to consider local processes involved in adhesion.