Synthesis and characterization of small pore thick-walled SBA-16 templated by oligomeric surfactant with ultra-long hydrophilic chains

Small pore (∼2.6 nm) thick-walled (7.7 nm) cage-like cubic mesoporous silica materials SBA-16 (ST-SBA-16) have been synthesized by using oligomeric surfactant Brij700 (polyoxyethylene (100) stearyl ether, C₁₈H₃₇EO₁₀₀) with ultra-long hydrophilic chains. Their ordered mesostructures were characterized by X-ray diffraction patterns (XRD), transmission electron microscopy (TEM), and nitrogen sorption analysis. Nuclear magnetic resonance (NMR) and infrared spectroscopy (IR) results show that ST-SBA-16 products have large numbers of silanol groups. The mesoscopic ordering of ST-SBA-16 can be greatly improved by the addition of suitable amount of co-surfactants, such as 1,3,5-trimethylbenzene (TMB). The effects of the synthesis parameters on the structure properties of ST-SBA-16 have also been systematically investigated. It is shown that the total pore volume can be enlarged from 0.31 to 0.51 cm³ g^-1 by the addition of TMB, pore diameter can be augmented from 2.6 to 4.0 nm by increasing the synthesis temperature from 5 to 40 °C and the surface area can be effectively tailored by changing the hydrothermal treatment time and the calcination temperature.