Odd-Even Effect in Synthesis of Mesoporous Silica Using Long-Chain Acyl-L-Alanine Sodium Salt Templating.

In this research, hexagonal and cubic mesoporous silica with ordered parallel pore channels was synthesized using odd chain-length N-undecanoyl-L-alanine sodium salt and even chain-length N-lauroyl-L-alanine sodium salt as template respectively. Aminopropylsiloxane was used as the co-structure-directing agents (CSDA). The ordered mesostructure was characterized by infrared spectroscopy, small X-ray diffraction patterns (XRD), scanning electron microscope (SEM), trasmission electron microscope (TEM), and nitrogen sorption analysis. The results indicated that mesoporous silica which was prepared by asymmetric odd chain-length surfactants presented a looser strucuture with large volume than mesoporous silica prepared by the even chain-length surfactant. It led to the transformation from 2D hexagonal (p6mm) phase to cubic (Ia¯3d) mesophase.