Manipulating the Growth and Disassembly of Layer-by-Layer Polymer Thin Films

Multilayered thin films have been the focus of intense research because of their vast array of applications.  We investigate the growth and disassembly under different pH conditions of layer-by-layer (LbL) films composed of oppositely charged polyelectrolytes (including poly(diallyldimethylammonium chloride) (PDDA), poly(styrene sulfonate) (PSS), and poly(acrylic acid) (PAA)) and synthetic clays.  We focus on the fundamentals governing the LbL assembly and triggered disassembly in order to get a better understanding of the mechanisms that control the internal ordering and organization in these films.  We have confirmed the presence of layering in these nanostructures by scanning electron microscopy (SEM), obtained the surface roughness via atomic force microscopy (AFM), determined the regular spacing in these layers by X-ray diffraction (XRD), and studied the layer growth and disassembly using UV-vis absorbance spectroscopy.  We evaluate the structural characteristics and properties of these multilayers, and we are especially interested in investigating their sensitivity and stability to external stimuli such as pH, temperature, humidity, and ionic strength.