(47a) Crystalline Order In Nanoparticulate Thin Films by Continuous Convective Assembly

Ordered films assembled from discrete nanoparticles have been a topic of interest in the recent literature. Convective assembly as a general phenomenon, and extensions to it such as continuous substrate withdrawal and controlled solvent evaporation, seems to be a promising route to cheap and scalable nanoparticulate film fabrication. While there are some recent works that branch out to explore the application of convective assembly to non-spherical particles, we find that even spherical nanoparticles (5 to 25 nm silica) in clean aqueous sols prove difficult to order into colloidal crystal films via convective assemby. That is despite the fact that settling and drying these sols in a non-convective assembly results in monoliths with an apparently high degree of crystallinity. This presentation will discuss some experimental explorations of processing conditions during convective assembly on the quality, i.e. structural order and uniformity, of the final nanoparticulate film.