Anisotropic Structure and Transport in Self-Assembled Layered Polymer−Clay Nanocomposites

• Published in: Langmuir Vol. 23; no. 16; pp. 8515 - 8521
• Main Authors: Lutkenhaus, Jodie L, Olivetti, Elsa A, Verploegen, Eric A, Cord, Bryan M, Sadoway, Donald R, Hammond, Paula T
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 31.07.2007
• Subjects: Aluminum Silicates - chemistry; Anisotropy; Chemistry; Colloidal state and disperse state; Electrochemistry; Exact sciences and technology; General and physical chemistry; Imines - chemistry; Nanocomposites - chemistry; Polyethylene Glycols - chemistry; Polyethylenes - chemistry; Static Electricity; Surface physical chemistry; Self-assembled layer; Relative humidity; Atomic force microscopy; Correlation; Laponite; X ray microscopy; Film; Hydrogen; X ray; Small angle X ray scattering; Ethylene oxide polymer; Nanocomposite; Structure; Clay; Scanning electron microscopy; Grazing incidence; Electrostatic interaction; Ion transport; Polymer; Imine; X ray diffraction; Photon; Ellipsometry; Anisotropy; Electrochemistry; Impedance
• ISSN: 0743-7463; 1520-5827
• DOI: 10.1021/la700432p

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.