Synthesis and Characterization of Silica Nanotubes with Radially Oriented Mesopores

Abstract

Hierarchical silica nanotubes with radially oriented mesoporous channels perpendicular to the central axis of the tube were synthesized by using self‐assembled chiral anionic surfactant, co‐structure directing agent (CSDA) and silica precursor. The average inner diameter and the wall thickness were ∼94, ∼62, and ∼62 nm and to ∼27, ∼33, and ∼45 nm, respectively, by manipulating the synthesis gel composition, while the diameter of the wall mesopores was kept constant at ∼4 nm. These materials with such a unique structure were produced only with chiral surfactant and achiral or racemic surfactant did not give rise to mesoporous silica nanotubes. The existence of helicity in the lipid bilayer template was confirmed by means of circular dichroism spectroscopy. The mesoporous penetrating from outside to inside of silica nanotubes are thought to originate from the initial formation of self‐assembled lipid tubes with helical bilayers, which in turn re‐assemble to form the mesopores in the wall of the nanotubes upon addition of co‐structure directing agent and silica source.

Organically Functionalized Mesoporous Silica by Co‐structure‐Directing Route

“…AMS nanotubes with disordered radial mesopores have been prepared at 30 ° C by using various anionic surfactants, typically C 14 AlaS, as the template. [ 91 ] By investigating the initial surfactant gel and intermediate products in the formation of the nanotubes, a mechanism has been proposed, emphasizing the templating of the preformed bilayered tube-like gels of the surfactant for the mesoporous silica tubes. In another work, when C 14 AlaS is used as the template at the reaction temperature of 0 ° C, helical silica ribbons with disordered mesopores have been prepared, which in a similar manner come from templating of the ribbon-like gel of the anionic surfactant (Figure 7 f).…”

Functional Mesoporous Material Derived from 3D Net‐Linked SBA‐15

“…[12][13][14][15][16][17][18] Also, the field effects, for example, gravitational, electric, magnetic, hydrodynamic, shear, and stress forces, [19] can influence the final morphology to a high degree. Until now a variety of mesoporous materials with particular micro-and macromorphologies, such as spheres, [20,21] rods, [22] fibers, [23] tubes, [24] thin films, [25] membranes, [26] monoliths, [27] and crystals, [28] have been prepared by adjusting the synthetic conditions. Nonetheless, some special techniques are necessary in these preparations, for instance solvent evaporation, [29] two-phase systems, [30,31] or special templates, such as a single-strand spider silk.…”

Synthesis of Silica Nanotube Using Myelin Figure as Template and their Formation Mechanism

“…Since Kuroda 5 and the company Mobil 6 reported the preparation of mesoporous silica, silica particles with various nanostructures including porous, hollow, and core-shell structures have been developed. In particular, silica nanotubes have recently attracted attention as these structures are known for biological compatibility, photoluminescence properties, low density, high-specific surface area, and the capability to incorporate materials; therefore, there are many potential applications of these structures as light materials, absorbing materials, separating agents, heat insulators, catalysts, biosensors, and nano-sized using the soft template method with chiral surfactants 19 , cationic 20,22 or anionic 21,22 surfactants, and hexagonal liquid crystals comprised of triblock copolymer surfactants or lipid nanotubes 23 as the template.…”