POLYMER DIFFUSION ACROSS INTERFACES IN LATEX FILMS

Latex films represent a high-surface area analogue of the polymer welding phenomenon. In both instances, the growth in strength of the joint is coupled to the diffusion of polymer molecules across a polymer-polymer interface. In order to observe this diffusion, one needs contrast. Here the contrast is provided by labeling half of the poly(butyl methacrylate) microspheres with a donor group (phenanthrene) and the other half with an acceptor (anthracene). Polymer interdiffusion leads to a growth in the extent of direct nonradiative energy transfer observed when the phenanthrenes are selectively excited with UV light. In this way we are able to study polymer interdiffusion in latex films under a wide variety of conditions, i.e., as a function of temperature and of polymer molecular weight and in the presence of plasticizers.