New poly(ethylene oxide)-clay composites

This paper reports a new mechanism for the formation of clay intercalates containing poly(ethylene oxide) (PEO). This mechanism permits formation of a two-dimensional PEO crystal phase. Under acidic conditions, polymer adsorption occurs through an ion-exchange process that is mediated by oxonium cation formation. A single phase exhibiting a plateau in the d(001) reflections of 19 Angstrom is formed at a polymer/clay stoichiometry of 0.5 g/g. This two-dimensional PEO crystal phase has a higher melting temperature than its three-dimensional counterpart because it is confined within the clay galleries. Unlike previously reported methods for forming PEO/clay intercalates, oxonium ion exchange produces structures whose basal spacings increase with increasing polymer molecular weight.