Formation and rheological behavior of wormlike micelles in a catanionic system of fluoroacetic acid and tetradecyldimethylaminoxide

From catanionic fluoro-/hydro-carbon mixtures of fluoroacetic acid (CF3COOH) and tetradecyldimethyl-aminoxide (C(14)DMAO) in water, viscoelastic wormlike micelles are successfully constructed which are determined by cryo-TEM measurements. It is found that the formation and rheological behavior of the wormlike micelles are greatly affected by the total concentration and mixing ratio of CF3COOH and C(14)DMAO as well as temperature. The driving force for the formation of wormlike micelles here is considered to be the electrostatic attractive interaction between the two molecules which is confirmed by H-1 NMR measurements. As far as we know, such wormlike micelles formed from the catanionic mixtures of fluorofatty acids and hydrocarbon surfactants have been rarely reported. Our work provides a simple method through mixing a perfluorofatty acid with a hydrocarbon surfactant to construct and understand the formation mechanism of catanionic fluoro-/hydro-carbon wormlike micelles, which should be a great advance in the fundamental research of wormlike micelles.