(93d) Morphology-Controlled Synthesis of Mesoporous Silica with Cotemplate of P123 and [Dmim]Cl

Morphology-controlled Synthesis of Mesoporous Silica with Cotemplate of P123 and [Dmim]Cl

Xiaowei Ji¹, Tuanchun Liu¹, Shaokun Tang^{1,2 *}

¹ Key Laboratory for Green Chemical Technology of Ministry of Education, School of Chemical Engineering & Technology, Tianjin University, Tianjin 300072, China;

² Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin University, Tianjin 300072, China

*Corresponding author. Tel: +86-22-27408578; E-mail address: shktang@tju.edu.cn (S. K. Tang)

  Mesoporous silica tubes has been successfully synthesized via sol-gel process with P123 (EO₂₀PO₇₀EO₂₀) and an ionic liquid ([Dmim]Cl) as the cotemplate and tetraethyl orthosilicate (TEOS) as the precursor. Uniform silica hollow spheres with diameters of 2-6 μm were synthesized with the single template of [Dmim]Cl, while highly ordered mesoporous silica with irregular shape was obtained with only P123 as the template. However, the morphology transformation from spheres to tubes of silica could be controlled by the cotemplate of P123 and [Dmim]Cl. The silica hollow spheres were gradually elongated and transformed into tubes by simply increasing the molar ratio of P123 to [Dmim]Cl. The uniform silica tubes with length of 15 μm, outer diameter of 3 μm and inner diameter of  2 μm were prepared when the P123/[Dmim]Cl molar ratio reached 0.09. The TEM images show that the synthesized silica tube walls possess highly ordered mesopores. N₂ adsorption/desorption experiment indicates that the pore diameter is centered at 3.6 nm, the specific area is up to 872 m²g^-1 and the pore volume is 0.86 cm³g^-1. We propose the possible mechanism that the interaction of the ionic liquid with the precursor by hydrogen-co-π-π stack result in the formation of silica hollow spheres; while adding P123 into the system, [Dmim]Cl can be self-assembled along the inner wall of cylindrical P123 micelles and TEOS are attached on the outside surface of P123 micelles by hydrogen bonds. The silica tubes were finally obtained by calcination to remove the cotemplate over 550 °C.

Acknowledgements

  This project was financially supported by the National Natural Science Foundation of China (21206118, 21328601), the Natural Science Foundation of Tianjin of China (12JCYBJC13500) and PetroChina Innovation Foundation (2013D-5006-0402).