Abstract:
While a body of literature on the spreading dynamics of surfactants and a few studies on the spreading dynamics
of nanocolloids exist, to the best of the authors’ knowledge, there are no reports on the effect of presence of surfactants on the
spreading dynamics of nanocolloidal suspensions. For the first time the present study reports an extensive experimental and
theoretical study on the effect of surfactant impregnated nanocolloidal complex fluids in modulating the spreading dynamics. A
segregation analysis of the effect of surfactants alone, nanoparticle alone, and the combined effect of nanoparticle and surfactants
in altering the spreading dynamics have been studied in detail. The spreading dynamics of nanocolloidal solutions alone and of
the surfactant impregnated nanocolloidal solutions are found to be grossly different, and particle morphology is found to play a
predominant role. For the first time the present study experimentally proves that the classical Tanner’s law is disobeyed by the
complex fluids in the case of particle alone and combined particle and surfactant case. We also discuss the role of imbibitions
across the particle wedge in the precursor film in tuning spreading dynamics. We propose an analytical model to predict the
nature of dependency of contact radius on time for the complex colloids. A detailed theoretical examination of the governing
factors, the interacting forces at the three phase contact line, and the effects of interplay of surfactants and the nanoparticles at the
precursor film in modulating the spreading dynamics has been presented for such complex colloids.
