Synthesis of 3-dimensional mesoporous silica using a di-block copolymer template

Exploring polymeric surfactants as templates for synthesizing ordered mesoporous silicas has become increasingly important for both academic interests and industrial applications. In this work, we employed C16EO40, a di-block copolymer polyethylene- poly(ethylene oxide), as template in an attempt to synthesize a modified 3-dimensional wormhole mesoporous silicas (WMS-39). In addition, various synthesizing conditions were investigated, including pre-hydrolysis time of TEOS, reaction temperatures and the ratios of TEOS to template. The products were characterized using powder XRD, TEM, 29Si MAS NMR and nitrogen adsorption measurements. The characteristics of as-synthesized mesoporous silica were compared with SBA-15, a highly ordered mesoporous silica, prepared using non-ionic tri-block copolymers of poly(ethylene oxide)–poly(propylene oxide)–poly(ethylene oxide) as templates. The WMS- 39 materials have a BET surface area of 600–970 m2/g and narrowly distributed pore diameter around 3.9 nm. The morphology of WMS-39 was found to be wormhole framework as indicated in TEM diagrams. Thermal transformation of the as-synthesized mesoporous materials were carefully analyzed with TGA/DTA. Findings obtained from this work enable us to propose a modified assembly mechanism of mesoporous silicas.