Porous oxide thin layers using mesophase templating

Abstract

Hexagonal mesoporous silica layers were first prepared by the sol-gel route from solutions containing silicon alkoxides as silica precursors and alkyltrimethylammonium bromides to form the templating liquid crystal mesophase. The synthesis conditions required to obtain well-ordered crack-free layers were investigated. Two main synthesis parameters were identified. The first one is the aging time of the sol before deposition which defines the size of the inorganic cluster before the thin layer deposition and the simultaneous phase formation. The second important synthesis parameter is the surfactant volume fraction in the medium after the departure of the volatile components. Well-ordered hexagonal layers were obtained for surfactant volume fractions in agreement with the water-surfactant binary diagram. These synthesis conditions were extended to cubic and lamellar phases and to other types of surfactants, gemini (cationic surfactants with two polar head groups) and non-ionic triblock copolymers. First results concerning the extension of this approach to the preparation of alumina thin layers are finally presented.

Effect of surfactant in a modified sol on the physicochemical properties and photocatalytic activity of crystalline TiO2 nanoparticles

“…Compared to other commonly used toxic additives (i.e., long-chain ammonium salts), these organics are relatively inexpensive, biodegradable, nontoxic, and easily-removable and exhibit the ability to control large inorganic clusters [28][29][30]. According to quasi elastic light scattering data and a fluorescent probe study for the Pluronic block copolymer, further addition of EO/PO block copolymer after monolayer saturation on particle surface does not lead to classical micellization as in Tween surfactant [31].…”

Humidity-controlled mesostructuration in CTAB-templated silica thin film processing. The existence of a modulable steady state

“…2,3 This method has been applied to prepare silica and transition metal oxide films, using various inorganic precursors and types of surfactant. [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] Nevertheless, because of the versatile properties of silica, most previous works focused on the cetyltrimethylammonium bromide-tetraethyl orthosilicate (CTAB-TEOS) system in acidic media, the former acting as the structure directing agent and the latter as the precursor. Various mesoporous structures have been obtained with this combination, including disordered (D), lamellar (L), 2D-hexagonal (P6m), 3D-hexagonal (P6 3 /mmc) and cubic (Pm3n) structures.…”

One pot synthesis of hierarchical porous silica membrane material with dispersed Pt nanoparticles using a microwave-assisted sol–gel route

“…Ni, Pd and Rh) in various types of hierarchical single or mixed oxide systems like TiO 2 , Al 2 O 3 , SiO 2 -TiO 2 or SiO 2 -Al 2 O 3 , by exploiting our knowledge of the preparation of mesostructured thin films and membranes. 34,[38][39][40]…”