INTERACTIONS OF IONIC SURFACTANTS WITH GELATIN IN FLUID SOLUTIONS ANDTHE GEL STATE STUDIED BY FLUORESCENCE TECHNIQUES, POTENTIOMETRY, AND MEASUREMENTS OF VISCOSITY AND GEL STRENGTH

The photobehavior of pyrene (fine structure of the monomeric fluoresce nce band; excited state lifetimes; excimer/monomeric fluorescence inte nsity ratios and excited state quenching rates by oxygen) in fluid sol utions of gelatin and in the gel state, both in the absence and presen ce of ionic surfactants, has been examined. Surfactants considered wer e sodium dodecylsulfate and dodecyltrimethylammonium bromide. Potentio metric measurements performed by using surfactant selective electrodes allowed for the determination of the binding capacity of the surfacta nts onto gelatin in the gel state. When complemented with viscosity an d gel strength measurements, the results obtained allow for a discussi on of the effects of the surfactant-gelatin interactions on microscopi c properties of the solutions or gels and their relation with macrosco pic properties.