Water-Soluble Copolymers .58. Associative Interactions and Photophysical Behavior of Amphiphilic Terpolymers Prepared by Modification of Maleic Anhydride Ethyl Vinyl Ether Copolymers

A series of amphiphilic terpolymers were prepared by sequentially copolymerizing maleic anhydride and ethyl vinyl ether, adding octyl-, dodecyl-, or naphthylamine, and then hydrolyzing the remaining anhydride units. Viscosity studies indicate that these amphiphilic systems form intramolecular associations in dilute and semidilute solutions at various values of pH and ionic strength. The dodecyl terpolymers show more pronounced hydrophobic associations than do the octyl analogs. Change in solution pH or addition of NaCl lowers significantly the viscosity of the polymer solutions, indicating more collapsed conformations. Fluorescence lifetimes increase with increasing hydrophobe content. The lifetime of the monomer emission decreases with increasing pH, demonstrating a more hydrated environment experienced by the probe within the polymer coil. I~IM values of the terpolymers with low hydrophobe content decrease with increasing pH from 3 to 10 while the terpolymers with moderate hydrophobe content exhibit a maximum I~IM in the same pH range. Systems with high hydrophobe content show little pH dependence. These results are interpreted in terms of the relative concentration of the chromophore in the hydrophobic domains as well as the change in the mobility of the naphthyl labels