The behavior of fluorinated surfactant F(CF2)8C2H4(OC2H4)9OH in water solution was investigated, and the preparation ofmesoporous molecular sieves was achieved. A direct micellar phase (L1) and a hexagonal (H1) liquid crystal were found. Small-angle X-ray scattering measurements proved that the hydrophobic chains are completely extended and that the cross sectional area remains constant in H1. At 80 degrees C, materials with a hexagonal array of their channel are prepared via a cooperative templating type mechanism in a wide range of surfactant concentrations (5-20 wt %). Decreasing the hydrothermal temperature leads to the formation ofwormhole-like structure. In this case the channel arrangement is no longer governed by the surfactant behavior but by the silica condensation and polymerization. An increase of the mean pore diameter with heating temperature is noted. This result is associated with changes of aggregation number with temperature. A comparison of the characteristics of the materials obtained with both hydrogenated and fluorinated surfactants is also made.

Surfactant templating techniques based on electrostatic, hydrogen-bonding, covalent, and van der Waals interactions between organic and inorganic species have been developed for the synthesis of materials with a narrow mesopore size distribution and controlled pore structure. [1,2] The use of block copolymers was recently shown to extend the pore sizes of ordered mesoporous oxides up to ten nanometers. [3,4] In addition, macroporous materials with pore sizes ranging from 100 nm to 1 mm can be obtained using latex spheres as templating agents. [5][6][7][8] The fabrication of hierarchically ordered structures at multiple length scales has attracted much interest from both a fundamental and practical viewpoint. [9,10] The combination of surfactant and colloidal crystal templating methods, together with microfabrication techniques allows the construction of hierarchical micro/meso/ macroporous architectures. [10][11][12][13][14][15] In this report, hierarchical mesoporous metal oxides with a novel macroporous architecture were synthesized in one step by single-surfactant templating without the need for polymeric spheres to act as a template that generates the macroporous structure. Polyethylene oxide (PEO) surfactants were used, which have been shown to efficiently organize mesoporous materials with structures of disordered wormhole-like MSU-type [16][17][18] and ordered SBA-n [19] and CMI-1 [20] materials. The occurrence of pores with a bimodal pore-size distribution in mesoporous materials is important and useful for both catalysis and the engineering of pore systems.[21]Mesoporous metal-oxide molecular sieves with macroporous structures are of interest as potential catalysts and sorbents, partly because the textural mesopores and intrinsic interconnected pore systems of macrostructures should efficiently transport guest species to framework binding sites. Biomimetic vesicular structures can be formed when the ionic strength of the nonionic surfactant solution is raised from that of the pure aqueous solution through the modification of PEOÀH 2 O hydrogen bonding; one kind of bimodal mesoporous silica has been synthesized by adding dilute electrolytes during PEO-templating.[22] Spongelike silica membranes with three-dimensional meso-macrostructures (that is, materials composed of mesopores of 2-50 nm in diameter, and macropores with diameters of between 50 nm and several micrometers) were synthesized from an electrolyte phase of a block copolymer/silica system, though inorganic salt crystals inevitably grew together with the silica membrane.[23] Mesomacroporous niobium oxides have also been prepared by adding NaCl to a ligand-assisted templating mixture of niobium ethoxide and amine surfactants; the salt was emphasized as being necessary for macropore (vesicle) formation. [24] We have used a simple method to prepare mesoporous metal oxides, such as TiO 2 and ZrO 2 , with macroporous hierarchical structure by the cooperative assembly of nonionic alkyl-PEO surfactants and inorganic precursors derived from metal alkoxi...

Surfactant templating techniques based on electrostatic, hydrogen-bonding, covalent, and van der Waals interactions between organic and inorganic species have been developed for the synthesis of materials with a narrow mesopore size distribution and controlled pore structure. [1,2] The use of block copolymers was recently shown to extend the pore sizes of ordered mesoporous oxides up to ten nanometers. [3,4] In addition, macroporous materials with pore sizes ranging from 100 nm to 1 mm can be obtained using latex spheres as templating agents. [5][6][7][8] The fabrication of hierarchically ordered structures at multiple length scales has attracted much interest from both a fundamental and practical viewpoint. [9,10] The combination of surfactant and colloidal crystal templating methods, together with microfabrication techniques allows the construction of hierarchical micro/meso/ macroporous architectures. [10][11][12][13][14][15] In this report, hierarchical mesoporous metal oxides with a novel macroporous architecture were synthesized in one step by single-surfactant templating without the need for polymeric spheres to act as a template that generates the macroporous structure. Polyethylene oxide (PEO) surfactants were used, which have been shown to efficiently organize mesoporous materials with structures of disordered wormhole-like MSU-type [16][17][18] and ordered SBA-n [19] and CMI-1 [20] materials. The occurrence of pores with a bimodal pore-size distribution in mesoporous materials is important and useful for both catalysis and the engineering of pore systems.[21]Mesoporous metal-oxide molecular sieves with macroporous structures are of interest as potential catalysts and sorbents, partly because the textural mesopores and intrinsic interconnected pore systems of macrostructures should efficiently transport guest species to framework binding sites. Biomimetic vesicular structures can be formed when the ionic strength of the nonionic surfactant solution is raised from that of the pure aqueous solution through the modification of PEOÀH 2 O hydrogen bonding; one kind of bimodal mesoporous silica has been synthesized by adding dilute electrolytes during PEO-templating.[22] Spongelike silica membranes with three-dimensional meso-macrostructures (that is, materials composed of mesopores of 2-50 nm in diameter, and macropores with diameters of between 50 nm and several micrometers) were synthesized from an electrolyte phase of a block copolymer/silica system, though inorganic salt crystals inevitably grew together with the silica membrane.[23] Mesomacroporous niobium oxides have also been prepared by adding NaCl to a ligand-assisted templating mixture of niobium ethoxide and amine surfactants; the salt was emphasized as being necessary for macropore (vesicle) formation. [24] We have used a simple method to prepare mesoporous metal oxides, such as TiO 2 and ZrO 2 , with macroporous hierarchical structure by the cooperative assembly of nonionic alkyl-PEO surfactants and inorganic precursors derived from metal alkoxi...

Decane has been used as swelling agent to enlarge the pore size of pure silica MCM-41 materials. The synthesis conditions such as the swelling agent/surfactant molar ratio, the adding sequence of swelling agent, etc., have been studied. The role of decane and the effect of crystallization time and temperature on the synthesis have also been discussed. Final compounds were intensively characterized by several techniques (XRD diffraction, SEM, TEM, and nitrogen adsorption-desorption analysis). The present work shows that decane is an effective expander to enlarge the pore size of mesoporous materials. Two possible mechanisms have been proposed to describe the swelling effect of decane molecules. The synthesis of mesoporous materials can be explained by different steps, which have been observed in the synthesis course of zeolites.