Stepwise adsorption for the formation of multilayer thin films

The first section of this dissertation describes a detailed study of how the swellability of polyelectrolyte/clay multilayer films by water can be minimized either during either formation or with a post-treatment. Specifically, film swellability can be reduced by either preparing the film using a lower concentration of polyelectrolyte or by using larger clay platelets. A second method for reducing film swellability was to post-treat the polyelectrolyte/clay multilayers using sol-gel chemistry. These studies resulted in data that require the internal structure of the polyelectrolyte/clay multilayer films to be described as containing swellable amorphous regions, non-swellable amorphous regions, and non-swellable polyelectrolyte/clay crystallites. In order to analyze the lateral dimensions of the clay platelets used in these studies, a technique for imaging clay particles by scanning electron microscopy (SEM) was developed.; An out-growth of the sol-gel study was the discovery of a method to form both titanium (hydr)oxide and porous silica films by electrostatic deposition. Using a titanium coordination compound and a polyelectrolyte, titanium (hydr)oxide films of controlled thickness could be formed. It was also possible to form silica films of tunable refractive index and controlled thickness by adsorbing silica species from the sol onto a polyelectrolyte-treated surface. Scanning electron microscopy of the resulting films revealed that the tunability in refractive index was the result of variable packing of the constituent silica particles within these films.; A method of incorporating nonpolar polymers within polyelectrolyte multilayers was also developed. The incorporation of polystyrene within a polyelectrolyte film reduced the ability of that film to sorb water from the vapor and swell. Additionally, through the use of a light-emitting polymer, it was possible to form films with potential use as light-emitting diodes. Finally, an early study examined the role of the bulk glass-transition temperature of a polymer on its surface dynamics above and below that temperature. Our study found that while the bulk glass transition affects the limiting extent of chain movement, short-range movement of surface chains was not prevented.