Hydration and internal properties of polyelectrolyte multilayers

In this review we summarize novel aspects of the hydration and internal properties of polyelectrolyte multilayers formed by layer-by-layer assembly. Reflectivity techniques monitor the water content and swelling behavior, while spin relaxation monitors water mobility. Odd-even effects in dependence on the number of layers are discussed in terms of an influence of the terminating layer. Other novel methodological approaches like X-ray microscopy or NMR cryoporometry address the water content in hollow capsules, and the water pore size distribution, respectively. Multilayer material properties are relevant for different applications. As a novel concept, dielectric properties are monitored in a field effect transistor device. Ion mobility and redox processes in multilayers are revealed by the electrochemical properties. Mechanical properties of multilayers, studied by colloidal probe atomic force microscopy depend on the conformation of the polymers involved. (c) 2007 Elsevier B.V. All rights reserved.