RE-EXAMINATION OF POLYSTYRENE-POLYSTYRENE HOMO INTERPENETRATING POLYMER NETWORKS - ASPECTS OF RELATIVE NETWORK CONTINUITY AND INTERNETWORK COUPLING

Sequential interpenetrating polymer networks, IPN's, are synthesized by swelling a cross-linked polymer I with monomer II, plus cross-linking and activating agents, and polymerizing II in situ. The materials are called homo-IPN's if polymers I and II are chemically identical. Because of the special swelling and mutual dilution effects encountered in sequential IPN's, special equations were derived for their rubbery modulus and equilibrium swelling. The new equations were used to analyze polystyrene/polystyrene homo-IPN swelling and rubbery modulus data obtained by four different laboratories. In the fully swollen state, there was no evidence for IPN related physical cross-links, but some data supported the concept of network I domination. In the bulk state, network I clearly dominates network II because of its greater continuity in space. There is some conflicting data supporting added physical cross-links. © 1979, American Chemical Society. All rights reserved.