r Manipulating polymer connectivity to control interracial fracture

By studying model polymeric networks which only differ in their connectivity, the connectivity is shown to strongly control the stress-strain response and failure modes. The sequence of molecular structural deformations that lead to failure are strongly dependent upon the network connectivity. A set of ideal, ordered networks are constructed to manipulate the deformation sequence to achieve a variety of adhesive qualities. Compared to random, dynamically formed networks, these ideal networks can be made to have either much larger or smaller failure stresses and strains. Unlike the random networks, the failure stress of an ideal network can be made close to the ideal stress equal to breaking all bonds to the substrate. By varying the number of bonds to the surface, the failure mode can be controlled to be either adhesive or cohesive. We know quite a bit of practical information about glues, but our understanding has large gaps [1-3]. The lack of understanding primarily comes from the difficulty of treating interfaces both experimentally and theoretically. In this report, the focus is on theoreticall