Polymer-Layered Silicate Nanocomposites from Model Surfactants at High Coverage

摘要

A series of experiments has been designed and conducted to test a recent model for the morphological behavior of polymer-layered silicate (PLS) nanocomposites, where a PLS nanocomposite is comprised of a homopolymer matrix, layered silicate clay mineral filler, and an organic surfactant modifier. For nearly complete exchange of naturally occurring interlayer cations with model surfactants synthesized for this study, the effect of surfactant length on the morphology of polymer-layered silicate nanocomposites has been examined. Here the surfactant and matrix homopolymer are both based on polystyrene and are therefore expected to be miscible. Small-angle x-ray scattering data show that there was no intercalation of the homopolymer into the modified layered silicate. This finding is consistent with autophobic dewetting such as that which occurs with densely grafted polymer brushes, based on high surfactant coverage within the layered silicate galleries.