Temperature-induced transitions from rodlike to globular micellar aggregates in aqueous cetyltrimethylammonium bromide in the presence of 9-anthrylalkanols

The flow behavior of aqueous solutions of cetyltrimethylammonium bromide was investigated as a function of temperature (15-50 degreesC) in the presence of various amounts of three 9-anthrylalkanols: 9-anthrylmethanol; 9-(1-(1-hydroxy)ethyl)anthracene; 9-(1-(1-hydroxy-2,2,2-trifluoro)ethyl)anthracene. Changes from non-Newtonian flow to Newtonian flow were observed upon increasing the temperature or decreasing the content of the 9-anthrylalkanols. The temperatures (between 291 and 321 K) and concentration ratios, at which these changes were observed, are distinct for the three solubilizates. Evaluations of rheological and light scattering data are in accordance with the presence of very big globular micellar aggregates (diameters up to 35 nm) in the Newtonian and long rodlike aggregates (lengths up to 800 nm) in the non-Newtonian cases. Electron micrographs confirm this interpretation.