Flow-Induced Silica Structure during in Situ Gelation of Wormy Micellar Solutions

In this study, we observed the flow-induced silica structure, which was formed during in situ gelation in the presence of wormlike micelles of cetyltrimethylammonium bromide and structure-forming additive, sodium salicylate. A silicon alkoxide of tetramethyl orthosilicate was used for the in situ gelation as a precursor of silica substrate. The silica formed the micrometer-sized zigzag structure in the absence of an imposed flow. In dilute regime, the morphology under steady shearing showed aligned texture and the small-scale zigzag morphology remained persistent. When the shear rate was sufficiently high that the viscosity of micellar solution shear thickened, the flow-induced interlayer coagulation was observed. Meanwhile, the degree of alignment was locally inhomogeneous at low shear rates in semidilute solution.