Solutions of extended, flexible cylindrical micelles, often known as wormlike micelles, have great potential as the base for viscoelastic complex fluids in oil recovery, drilling, and lubrication. Here, we study the morphology and nanostructural characteristics of a model wormlike micellar fluid formed from erucyl amidopropyl betaine (EAPB) in water as a function of a diverse range of additives relevant to complex fluid formulation. The wormlike micellar dispersions are extremely oleo-responsive, with even as little as 0.1% hydrocarbon oil causing a significant disruption of the network and a decrease in zero-shear viscosity of around 100-fold. Simple salts have little effect on the local structure of the wormlike micelles but result in the formation of fractal networks at larger length scales, whereas even tiny amounts of small organic species such as phenol can cause unexpected phase transitions. When forming mixtures with other surfactants, a vast array of self-assembled structures are formed, from spheres to ellipsoids, lamellae, and vesicles, offering the ultimate sensitivity in designing formulations with specific nanostructural characteristics.

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The aggregation behavior and flow characteristics of systems based on zwitterionic surfactant, erucyl amidopropyl betaine, silica and alumina nanoparticles in a wide range of surfactant concentrations from molecular to micellar solutions were studied using surface tensiometry, conductometry, dynamic and electrophoretic light scattering, and rheology techniques. The adsorption of zwitterionic surfactant molecules occurs on both positively and negatively charged surfaces via an electrostatic interaction mechanism. As a result, addition of a small amount silica nanoparticles (0.5-0.8 wt%) increases the surfactant solution's viscosity by more than two times.

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