Synthesis and characterization of poly(ethylene oxide) nanocomposites of misfit layer chalcogenides

Nanocomposites of poly(ethylene oxide) (PEO) and (PbS)(1,18) (TiS2)(2), a composite misfit layer sulfide were prepared by treating a lithium derivative in aqueous solutions of PEG. Under these conditions, the alkali metal intercalate readily exfoliates and rapidly reflocculates, thus trapping polymer molecules between sulfide layers. In this exfoliation and restacking process, Li+ ions are partially removed. Powder X-ray, electron diffraction, and IR results are consistent with one layer of helical PEO located at all TiS2-TiS2 interfaces and with empty PbS-TiS2 interfaces. Thermal deintercalation of the new phase is a complex process that occurs at an unusually high temperature; this sugggests strong interactions between the polymer and the host, probably involving the alkali ions and PEO chains. Hydrogen sulfide traces were also detected. Although the XRD pattern for the decomposition product exhibits the main diffraction peaks for the host, the peaks are broad and asymmetric, which suggests that the lattice undergoes significant changes that partially collapse the structure in poorly crystalline phases, (C) 1998 academic Press.