Anisotropic Structure and Transport in Self-Assembled Layered Polymer−Clay Nanocomposites
journal contributionposted on 31.07.2007, 00:00 by Jodie L. Lutkenhaus, Elsa A. Olivetti, Eric A. Verploegen, Bryan M. Cord, Donald R. Sadoway, Paula T. Hammond
Using the layer-by-layer (LbL) assembly technique, we create a polymer−clay structure from a unique combination of LbL materials: poly(ethylene imine), Laponite clay, and poly(ethylene oxide). This trilayer LbL structure is assembled using a combination of hydrogen bonding and electrostatic interactions. The films were characterized using ellipsometry, profilometry, X-ray photon spectroscopy, atomic force microscopy, scanning electron microscopy, wide-angle X-ray diffraction, grazing-incidence small-angle X-ray scattering, and electrochemical impedance spectroscopy (EIS). We observe a layered, anisotropic structure, which resulted in in-plane ion transport 100 times faster than cross-plane at 0% relative humidity. This study represents a first application of EIS in determining anisotropic ion transport in LbL assemblies and its correlation to structural anisotropy.