A novel route to inducing disorder in model polymer-layered silicate nanocomposites

The effects of the degree of silicate surface modification by organic surfactants and the nature of surfactant-matrix enthalpic interactions on polymer-layered silicate nanocomposite (PLSN) morphology have been systematically investigated. Using cation exchange to modify montmorillonite, a series of '' partially '' modified clays were prepared and used in turn to fabricate polystyrene (PS)-, poly(vinyl methyl ether) (PVME)-, and poly(methyl methacrylate) (PMMA)-matrix PLSNs via static melt intercalation. Small-angle X-ray scattering and transmission electron microscopy revealed that the morphological behavior of the PS-based '' partial '' coverage PLSNs was seemingly dependent on surfactant length, with the shortest surfactant providing the most significant disruption of the clay tactoids. Examination of the PMMA- and PVME-based PLSNs indicated that the nanocomposite morphology was only weakly affected by the nature of matrix surfactant enthalpic interactions. The results of modifying montmorillonite with 5.5 kg/mol PS-based surfactant at only 4.7% coverage and subsequent fabrication of PLSNs via static melt intercalation confirmed that clay tactoids can be disordered through appropriate control of the degree of surfactant coverage for a given surfactant length.