Kinetics and interpenetration of ionically self-assembled dendrimer and PAZO multilayers

Multilayer films comprised of a generation 3.0 dendrimer and NLO-active polyanion PAZO were formed by ionic self-assembly. The films were studied by UV-visible spectroscopy, single-wavelength ellipsometry, and second-harmonic generation. We show that the multilayer formation mechanism involves an initial adsorption of the polymer that reaches saturation after 5 min, while conformational changes equilibrate after 10 min. The terminal layer is more loosely packed than the nonterminal layers that have interpenetrated zones containing both the dendrimer and PAZO. Most of the anisotropic order of the NLO-active chromophores is thought to exist at the interfacial regions between these layers. From SHG polarization studies, we determine the angle of these ordered PAZO chromophores to be 20.5degrees +/- 5degrees with respect to the surface normal.