Ordered multilayer nanocomposites prepared by electrostatic layer-by-layer assembly between aluminosilicate nanoplatelets and substituted ionic polyacetylenes

Ordered multilayer nanocomposites have been prepared by electrostatic layer-by-layer assembly between exfoliated aluminosilicate nanoplatelets and substituted ionic polyacetylenes. Aluminosilicate saponite particles were exfoliated by means of extensive shaking and sonication of their water suspension. Atomic force microscopy and transmission electron microscopy data suggest that the exfoliated platelets have the shape of ultrathin disks with an average width of 170+/-30 nm. Conjugated ionic polyacetylene poly(N-octadodecyl-2-ethynylpyridinium bromide) (PEPy-C18) was synthesized by spontaneous polymerization of 2-ethynylpyridine quaternized with 1-bromooctadecane. Linear build-up of multilayer nanocomposites between the exfoliated saponite particles and substituted ionic polyacetylenes was monitored by T-TV-vis absorption spectroscopy. AFM surface topography of the resulting films indicates that the saponite platelets cover the entire surface of the underlying layers. TEM cross-sectional images of such films show that the saponite platelets are aligned parallel to the film surface to form ordered layers. Polarized UV-vis absorption spectroscopy suggests that the polyacetylene chains are oriented parallel to the surface of the saponite layers.