  We study theoretically situations where competition arises between an
interdiffusion process and a cross-linking chemical reaction at interfaces
between pieces of the same polymer material. An example of such a situation is
observable in the formation of latex films, where, in the presence of a
cross-linking additive, colloidal polymer particles initially in suspension
come at contact as the solvent evaporates, and, optimally, coalesce into a
continuous coating. We considered the low cross-link density situation in a
previous paper (A. Aradian, E. Raphael, P.-G. de Gennes, Macromolecules 33,
9444 (2000)), and presented a simple control parameter that determines the
final state of the interface. In the present article, with the help of simple
scaling arguments, we extend our description to higher cross-link densities. We
provide predictions for the strength of the interface in different favorable
and unfavorable regimes, and discuss how it can be optimized.
