Interpenetrating Networks (IPNs)

In the mid-1990s, in collaboration with Dr. R. De Voe at 3M, we investigated the morphology and the nature of polymer interfaces in a series of urethane-acrylate IPN's. The system of interest formed very different morphologies depending upon the order in which the monomers were reacted and cured. The attraction to industry was the possibility that several different products with different mechanical properties could be prepared from a single mixture of reactants, just by varying the processing conditions. IPNs are notoriously complex, and the most difficult issues to understand are the compositions of the individual phases and the nature of the interface between the phases. Here we introduced donor and acceptor dyes into the system, using our skills in synthesis to control their location in the urethane or acrylate backbone. From the energy transfer kinetics, we were able to determine the composition of individual microdomains in these IPNs. [see Macromolecules, 32, 3241-3248 (1999)].