Self-assembly of a non-ionic surfactant onto a clay mineral for the preparation of hybrid layered materials

摘要

The adsorption of the tri-ethylene glycol mono-n-decyl ether (C _(10)E_3) nonionic surfactant, characterized by its self-assembled lamellar phase above the critical micelle concentration (cmc), in a wide range of concentration, onto a layered clay mineral (montmorillonite) has been studied. C_(10)E_3 exhibits a high affinity for the montmorillonite (Mt) surface with an adsorption isotherm that differs strictly from previous studies on the adsorption of nonionic surfactants onto clay minerals for which a maximum of adsorption was reached below cmc. The self-organization in a lamellar phase changes the interaction potential between C_(10)E_3 and Mt, a surface that favors the aggregation of normal bilayers which expands the interlayer space at wide values (>40 ?) while keeping the exchangeable Na~+ cations conferring dual hydrophilic-hydrophobic behavior for the hybrid layered materials. Depending on the C_(10)E_3 phase state (in monomers or in a lamellar phase), the adsorption leads to four distinct surfactant arrangements (lateral layers to normal tilted bilayers) within the interlayer space of Mt. The hybrid layered materials show a thermal stability at 350 °C with a collapse of their interlayer space at 13 ? due to the degradation of the hydrocarbon chains of C_(10)E_3. FTIR during thermogravimetry analysis permits the identification of the portions of C_(10)E_3 corresponding to ethylene oxide groups in close interaction with the Mt surface. This journal is