Mesostructure Design with Gemini Surfactants: Supercage Formation in a Three-Dimensional Hexagonal Array

Abstract

At low temperatures, liquid crystal-like arrays made up of inorganic-cluster and organic molecular units readily undergo reversible lyotropic transformations. Gemini surfactants, with two quaternary ammonium head groups separated by a methylene chain of variable length and with each head group attached to a hydrophobic tail, can be used to control organic charge sitting relative to the bivariable hydrophobic tail configurations. This approach has led to the synthesis of a mesophase (SBA-2) that has three-dimensional hexagonal (P6(3)/mmc) symmetry, regular supercages that can be dimensionally tailored, and a large inner surface area. This mesostructure analog of a zeolite cage structure does not appear to have a lyotropic surfactant or lipid liquid crystal mesophase counterpart. Through the modification of gemini charge separation and each of the two organic tails, these syntheses can be used to optimize templating effects, including the synthesis of MCM-48 at room temperature.

Direct Synthesis and Characterization of Titanium-Substituted Mesoporous Molecular Sieve SBA-15

“…This is an indication of N 2 condensation and evaporation within interparticles 46 or of some impurity phase, such as lamellar mesostructures that are sometimes generated by liquid-crystaltemplated materials. 47 Figure 10 shows the 29 Si MAS NMR spectra for the series of as-synthesized Ti-SBAS-15 samples. Three bands centered at -93, -103, and -113 ppm are resolved, and these bands can be attributed to Si(OSi) x (OH) 4-x framework units where x ) 2 (Q 2 ), x ) 3 (Q 3 ), and x ) 4 (Q 4 ).…”

Surfactant effects on the microstructures of Fe3O4 nanoparticles synthesized by microemulsion method

“…About Gemini surfactants, there have the relevant reports on the application of template synthesis of various materials, such as gold particles and organized mesoporous silica [48][49][50]. Here, a Gemini surfactant dimethylene-1,2-bis(dodecyldimethylammonium bromide), abbreviated as 12-2-12, has been devised as surfactant phase to synthesize the nanosized Fe 3 O 4 particles in water-in-oil microemulsion.…”

π–π interaction of aromatic groups in amphiphilic molecules directing for single-crystalline mesostructured zeolite nanosheets

“…Long-chain alkyl-quaternary ammonium molecules are universally used to synthesize mesoporous silica materials through the self-assembled liquid crystal templating route [20][21][22] . Recently, Ryoo and coworkers 8 succeeded in synthesizing polycrystalline mesostructured MFI (zeolite framework code by International Zeolite Association) zeolite using designed bifunctional surfactants 7,8,23 , in which the connection of the head groups of the multiple quaternary ammoniums to hydrophobic alkyl chains is the indispensable factor for the effective structure-directing agent to simultaneously form MFI zeolite and a mesoscale micellar structure.…”