Research Grant Report
Synthesis and application of silica particles having helical mesopores
2009 Volume 17 Pages 17-20
Details
2009 Volume 17 Pages 17-20
We have developed the method for synthesizing mesoporous silica having helical channels by using anionic surfactants based on amino acids. During this research, we have established a simple and novel liquid-phase method for preparing uniform-sized silica nanospheres (SNSs) 8－400 nm in size. The SNSs were synthesized through hydrolysis and condensation reactions of TEOS in the emulsion system containing TEOS, water and basic amino acids such as lysine and arginine under weakly basic conditions (pH 9－10). After the reaction, uniform-sized SNSs were stably dispersed in homogeneous solutions without any precipitation. Interestingly, the arrangement of these SNSs into a cubic closed packed (ccp) structure was achieved simply by solvent evaporation. Thus formed SNSs can be categorized into well-ordered mesoporous silicas because they have three-dimensional, interparticle voids with high uniformity.
The size of the product silica spheres was affected by two factors, the proportion of the seed-solution and the ethanol / water ratio of the solvent. Thus uniform-sized silica nanospheres with the diameter ranging from 8 to 400 nm were successfully obtained. By adding a surfactant to the reactant solution, silica spheres with mesopores inside were also synthesized. Carbon replicas with well-ordered mesostructure were synthesized by using the array of silica nanospheres of diverse sizes as a template. The pore size of the carbon structure was easily regulated by varying the size of silica spheres. The pores were uniform in size and spherical; each of the spherical pores was also three-dimensionally interconnected to neighboring pores through small holes, which were attributed to the contact points between closely-packed silica spheres. Furthermore, by using the porous carbon replica as a template, transition metal oxides having three-dimensional mesopores were prepared. Some of the metal oxides were crystallized with the mesoporous structure retained.
