Effect of Layer Charge on the Intercalation of Poly(ethylene oxide) in Layered Silicates:  Implications on Nanocomposite Polymer Electrolytes

The effect of layer charge on the intercalation of poly(ethylene oxide) (PEO) was investigated using a series of reduced-charge montmorillonites and smectites with varying layer charge. The amount of intercalated polymer initially increases with layer charge but then decreases. In contrast, the amount of water present continuously increases. This water is mostly coordinated with the gallery cations. When PEO is intercalated, it replaces water molecules filling the space between the hydrated exchangeable cations. Molecular simulations confirm the experiments and show that the polymer oxygen atoms do not directly associate with the exchangeable cations, which are mostly coordinated to water molecules and surface oxygen atoms.