Self-organization and properties of dilute aqueous solutions of cetyltrimethylammonium bromide in a range of physiologically important temperatures

A combination of physicochemical methods (dynamic light scattering, nanoparticle tracking analysis, conductometry, tensiometry, and ESR spectroscopy) revealed that dilute solutions (1.10(-3), 1.0.10(-4), 1.0.10(-7), and 1.0.10(-9) mol L-1) of surfactant (cetyltrimethylammonium bromide) in a temperature range of 25-45 degrees C are self-organized dispersed systems. As the temperature increases, the systems undergo rearrangements specific for each studied concentration, which is reflected as nonmonotonic temperature dependences of the parameters of domains (1.10(-3) and 1.0.10(-4) mol L-1) and nanoassociates (1.0.10(-7) and 1.0.10(-9) mol L-1) and also as interrelated dependences of the conductivity of solutions with extremes at 30, 37, and 40 degrees C. The ESR experiments show a nonmonotonic decrease in the rotational diffusion correlation time (tau(cor)) of 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) in the temperature dependences of tau(cor) with the temperature increase from 25 to 45 degrees C and the appearance of two to three plateaus, one of which (in a range of 36-40 degrees C) is observed in the temperature dependences for all studied concentrations.