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...

First hierarchical titanium phosphate (TiPO) materials with multiple porosities of different lengths (meso-macroporous and meso-macro-macroporous) were synthesized by the self-formation process. The further tuning of the porous hierarchy by using the poly(ethylene oxide) surfactant technique was demonstrated. The macroporous structure (50-160 nm in size) of TiPO with mesoporous walls could be self-formed in the absence of any templatable agents, including surfactant molecules. On the basis of spontaneous structurization, the addition of a small quantity of nonionic poly(ethylene oxide) surfactant (e.g., 5%) led to an improvement in macroporosity in abundance and in regularity with a slight enlargement in macropore sizes to 80-250 nm. Interestingly, a secondary, larger macropore system with parallel channels 500-1000 nm in size was generated when the synthesis was performed with moderately increasing the content of surfactant (10%), giving rise to an unprecedented trimodal meso-macro-macroporous structure. A uniform three-dimensional co-continuous macroporous structure with accessible wormhole-like mesoporous walls was synthesized by using the higher content of surfactants. This is a direct demonstration of tailoring the porous hierarchy of different lengths integrated in one solid body by fine-tuning the self-formation process and the participation of surfactant. The synthesized hierarchical titanium phosphates possess interesting optical and acidic properties, which should be significant for large application potential from catalysis and separation to electrochromic devices, fuel cells, and bioactive materials.

A hierarchical structure of mesoporous-macroporous phosphated aluminum (oxyhydr)oxide (PAl) materials was prepared via a simple self-assembly process with the use of precursor aluminum secbutoxide in a mixed solution of H 3 PO 4 and Na 2 HPO 4 . Direct phosphation resulted in the incorporation of phosphorus into the inorganic framework of aluminum (oxyhydr)oxides by the Al-O-P bonds. The X-ray diffraction (XRD) patterns revealed that, despite slight phosphorus incorporation or phosphation, the frameworks of the as-synthesized autoclaved PAl samples remained in a crystalline phase of boehmite AlOOH-type, and their calcined products had a phase of γ-Al 2 O 3 -type. The macroporous structures are uniform, with sizes of 500-1800 nm, and the macropore walls are composed of accessible mesopores of a scaffold-like nanoparticle assembly. It is shown that the direct incorporation of phosphorus from a phosphate solution of the synthesis system can stabilize the framework of mesoporous-macroporous aluminum oxides with high surface areas and acidic properties. The present study also demonstrated that the surfactant (Brij 56) did not seem to have a direct role in the formation of macroporous structures, but significantly influenced the textural properties of the resultant PAl materials. The surface areas of surfactantsynthesized PAl exceeded 700 m 2 /g, which is almost two times of that of surfactantless-synthesized samples. The synthesized hierarchical PAl exhibited high thermal stability (at least 800°C), possessing surface hydroxyl groups and acid sites, which may attract much interest for practical applications, including catalysis.