RHEOLOGICAL PROPERTIES OF DYE ASSEMBLIES

This paper presents a detailed study of the rheological properties of aqueous solutions of pseudoisocyanine chloride. Even at very low conce ntrations, the solutions of this chromophore tend to form rod-shaped p articles, which are often called Jelly- or Scheibe-Aggregates. Above a critical concentration c, which is of the order of 10 mmol/L, one ob serves strong elastic properties and relaxation times of the order of 30 minutes. In this regime the shear modulus varies with volume fracti on as Phi(1.9). These phenomena are very similar to those observed in viscoelastic surfactant solutions. In contrast to aqueous solutions of entangled threadlike micelles, the relaxation process of chromophores cannot be described by simple monoexponential decay functions. This i s due to differences in the aggregation kinetics. This paper gives som e insights into the dynamic properties of these solutions, and describ es some interesting phenomena observed during flow.