We introduce a model system consisting of self-assembled polyamide anisotropic colloids suspended in an aqueous surfactant solution for studies of the dynamics of rod networks, gels, and glasses. The colloidal particles are formed by recrystallization of a polyamide from an aqueous surfactant phase at temperatures from 59 to 100 degrees C. The aspect ratio increases monotonically with temperature from T=59 degrees C to T=100 degrees C and rods with an aspect ratio r=8+/-1 to r=306+/-14 form. We show by confocal laser scanning microscopy and dynamic light scattering a structural transition from dilute rod behavior with diffusive dynamics to a homogeneous network structure with increasingly slow dynamics as the volume fraction is increased. Furthermore, increasing the aspect ratio of rods induces a similar structural transition from dilute rod behavior to a network structure, although at a lower volume fraction. Finally, we vary the pair potential between the rods by a polymer-induced depletion interaction and thereby observe an unexpected network-to-bundle transition. The bundles are several rod diameters wide and 1-2 rod lengths long. The rods appear to be ordered nematically within each bundle. The bundling transition leads to an order of magnitude decrease in the storage modulus of the suspensions. The results can be applied to develop strategies for complex fluid stabilization as well as for fundamental studies of rod gelation and vitrification.

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We report on the rheology of a lyotropic lamellar surfactant solution (SDS/dodecane/pentanol/ water), and identify a discontinuous transition between two shear thinning regimes which correspond to the low-stress lamellar phase and the more viscous shear-induced multilamellar vesicle, or "onion" phase. We study in detail the flow curve, stress as a function of shear rate, during the transition region, and present evidence that the region consists of a shear-banded phase where the material has macroscopically separated into bands of lamellae and onions stacked in the vorticity direction. We infer very slow and irregular transformations from lamellae to onions as the stress is increased through the two-phase region, and identify distinct events consistent with the nucleation of small fractions of onions that coexist with sheared lamellae.