Layer-by-Layer (LbL) assembly is a versatile technique to produce uniform and conformal thin films, involving the sequential deposition of oppositely charged species. Spray-assisted layer-by-layer assembly (spray LbL) accelerates the deposition process by delivering solutions of the charged species as a high-velocity mist. We investigate spray LbL involving oppositely charged silica nanoparticles and study the fundamental kinetics of the spray LbL process. A simple pseudo-first order rate model can be used to predict film thickness under various colloid concentrations, spray flow rates, and spray times. We show that the spray LbL mechanism consists of two mass transport steps in series: bulk spray flux to the substrate surface, followed by random motion of nanoparticles through a thin liquid film adhering to the substrate surface. The second transport step limits the overall deposition rate, and we examine the importance of a convective driving force in accelerating random motion close to the substrate.

Universality in spray-assisted layer-by-layer assembly of oppositely charged nanoparticles

244th National Meeting (2012)

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