Structural studies of polyurethane ionomer solutions. 2. Fluorescence

8-Anilino-1-naphthalenesulfonic acid (ANS) and pyrene fluorescent probes ha ve been used to investigate the interactions in solutions of model polyuret hane ionomers PU1 and PU4 in dimethylacetamide (DMAc) and N-methylformamide (NMF). PU1 and PU4 solutions in DMAc consist of loose aggregates and have no hydrophobic aggregation. PU4 solutions in NMF show the presence of hydro phobic aggregates due to NMF being a poor solvent for the ionomer backbone. PU1 solutions in NMF have a very-small amount of hydrophobic aggregation, indicating that increase in ionic content of the ionomer can eliminate back bone aggregation even in solvents that are poor solvents for the backbone. The results demonstrate the importance of polymer-solvent interactions and ionic content of the ionomer in determining the solution structure of ionom ers.