Intercalation and in situ polymerization of poly(alkylene oxide) derivatives within M⁺-montmorillonite (M = Li, Na, K)

We have synthesized a range of montmorillonite-based clay-polymer nanocomposites by intercalation of a variety of functionalized molecules having poly(ethylene oxide) and poly(propylene oxide) backbones from aqueous solution using a facile batch process. We focus on montmorillonite clays charge-balanced by cation exchange with Li⁺ and K⁺, but otherwise unmodified. Analysis by X-ray diffraction and thermal methods showed that intercalation occurred in all cases and that the composites displayed a range of interlayer spacings and organic content, from monolayer arrangements to pseudo-trilayer arrangements. Intercalated K⁺-montmorillonites had a propensity to exfoliate, in marked contrast to their resistance to swelling by water. Large-scale molecular dynamics simulations of selected composites were used to elucidate possible interlayer arrangements of the composites. Materials property studies showed that these clay-polymer composites had significantly increased Young's moduli compared to the unfilled polymer.