A dual-templating strategy for the scale-up synthesis of dendritic mesoporous silica nanospheres

• Published in: Green chemistry : an international journal and green chemistry resource : GC Vol. 19; no. 23; pp. 5575 - 5581
• Main Authors: Liu, Peng-Cheng, Yu, Ye-Jun, Peng, Bo, Ma, Shi-Yu, Ning, Tian-Yu, Shan, Bing-Qian, Yang, Tai-Qun, Xue, Qing-Song, Zhang, Kun, Wu, Peng
• Format: Journal Article
• Language: English
• Published: Cambridge Royal Society of Chemistry 2017
• Subjects: adsorption; anionic surfactants; Business competition; Catalysis; catalysts; catalytic activity; Cetyltrimethylammonium bromide; Cyclohexene; cyclohexenes; Dendritic structure; Epoxidation; epoxidation reactions; Green chemistry; iodides; Ions; Micelles; Nanoparticles; Nanospheres; Oligomers; Organic solvents; porous media; Silica; silicates; Silicon dioxide; solvents; Surfactants; Titanium
• ISSN: 1463-9262; 1463-9270; 1463-9270
• DOI: 10.1039/c7gc02139a

We have demonstrated a facile and green way to synthesize dendritic mesoporous silica nanoparticles (DMSNs) on an ultra-large scale (kg) with cetyltrimethylammonium bromide (CTAB) and an anionic surfactant as dual templates free of organic solvents. In contrast to its co-template role in tuning the packing parameter of the surfactant molecule organization, the anionic surfactant herein acts as a more strongly competitive counterion against the adsorption of negatively charged silicate oligomers (I − ) on the micelles. Based on the new understanding of the interaction between the cationic-anionic surfactant ionic pairs and the silicate oligomers, we proposed a dual template synergistically controlled micelle self-aggregated model to understand the formation mechanism of dendritic MSNs where the anionic surfactant stabilized micelles or micelle blocks are basic self-assembling building units for the formation of center-radial pore channel networks. By using one-pot in situ isomorphous substitution, the metal Ti atom can be easily incorporated into the silica frameworks of DMSNs, and the obtained Ti-DMSN catalyst shows a superior catalytic performance in the epoxidation of cyclohexene over the typical mesoporous Ti-MCM-41 silicas. Mesoporous silica nanoparticles with varied morphologies and pore structures were synthesized on the kilogram scale using cetyltrimethylammonium bromide and an anionic surfactant as co-templates.