ИСТИНА

Surfactant molecules can self-assemble and form long wormlike micelles, which can organize into an entangled network imparting viscoelastic properties to solutions. Surfactant molecules are bound by weak non-covalent interactions within the micelle, therefore viscoelastic micellar solutions are highly responsive to external stimuli, e.g. the addition of hydrocarbons. In the present work we investigate the transition of wormlike micelles into microemulsion droplets in surfactant and surfactant-polymer solutions induced by hydrocarbon [1]. First, we studied the effect of hydrocarbon on the rheology of wormilike micellar solutions. At very low hydrocarbon concentrations the solutions retain viscoelastic properties and Maxwell behavior, what is due to the presence of long entangled wormlike micelles. However, the micelles shorten and become more rigid, what results in a slight decrease of viscosity and plateau storage modulus. At intermediate hydrocarbon concentrations the network is gradually disrupted, what is due to the further shortening of wormlike micelles and transition to unentangled regime. This results in a drastic drop of viscosity and dissapearence of viscoelastic properties. At high hydrocarbon concentrations viscosity reaches the values close to that of water what indicates to the complete disruption of wormlike micelles and to the formation of microemulsion droplets. Then, we studied the effect of hydrocarbon on the solutions containing a common network of wormlike micelles and hydrophobically modified polymer. It was shown that the viscosity and storage modulus of the solutions decrease by several orders of magnitude upon addition of hydrocarbon, however, the amount of hydrocarbon needed to disrupt the network is higher than for pure surfactant solutions.