Régis Guégan

This article gives an overview of the preparation, applications, and limits of organoclay materials in the environment field. Organoclays are obtained by the combination of clay minerals and surfactants (quaternary alkyl ammonium salts and others) and are appropriate candidates for the adsorption of organic contaminants such as pesticides, herbicides, and pharmaceuticals that are more and more found in the water resource despite wastewater treatments. This review article focuses on novel organoc

We present a neutron scattering analysis of the structure of the smectic liquid crystal octylcyanobiphenyl (8CB) confined in one-dimensional nanopores of porous silicon films (PS). The smectic transition is completely suppressed, leading to the extension of a short-range ordered smectic phase aligned along the pore axis. It evolves reversibly over an extended temperature range, down to 50 K below the N-SmA transition in pure 8CB. This behavior strongly differs from previous observations of smect

A nonionic surfactant, triethylene glycol mono-n-decyl ether (C(10)E(3)), characterized by its lamellar phase state, was introduced in the interlayer of a Na-montmorillonite clay at several concentrations. The synthesized organoclays were characterized by small-angle X-ray scattering in conjunction with Fourier transform infrared spectroscopy and adsorption isotherms. Experiments showed that a bilayer of C(10)E(3) was intercalated into the interlayer space of the naturally exchanged Na-montmoril

The confinement of lysozyme in 3 layered materials based on montmorillonite and lamellar double hydroxides exhibiting different surface charges was studied. The protein structure and orientation in these materials were determined by X-ray diffraction, time resolved fluorescence and fluorescence anisotropy. For montmorillonite exchanged with sodium and modified with a non-ionic surfactant (tri-ethylene glycol mono n-decyl ether), the lysozyme was found to be located in the interlayer space with t

The adsorption of the tri-ethylene glycol mono-n-decyl ether (C10E3) 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. C10E3 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

4-n-octyl-4-cyanobiphenyl has been recently shown to display an unusual sequence of phases when confined into porous silicon (PSi). The gradual increase of oriented short-range smectic (SRS) correlations in place of a phase transition has been interpreted as a consequence of the anisotropic quenched disorder induced by confinement in PSi. Combining two quasielastic neutron scattering experiments with complementary energy resolutions, the authors present the first investigation of the individual

The aggregation of surfactants on solid surfaces as they are adsorbed from solution is the basis of numerous technological applications such as colloidal stabilization, ore flotation, and floor cleaning. The understanding of both the structure and the dynamics of surfactant aggregates applies to the development of alternative ways of preparing hybrid layered materials. For this purpose, we study the adsorption of the triethylene glycol mono n-decyl ether (C₁₀E₃) nonionic su