The influence of cosurfactants on the synthesis of hierarchically porous silica materials in a P123/cosurfactant/1,3,5-trimethylbenzene/water four-component microemulsion system

• The hierarchical porous silicas (HPS) were synthesized by using a four-component microemulsion system.
• HPS show the pore structures of disordered-SBA-15-type and mesocellular foams.
• The proposed mechanism for synthesizing HPS was put forward.
• All the obtained HPS have large pore volumes (about 1.4 cm3 g−1).

This research reported a micelle/microemulsion bimodal templating method to synthesize hierarchical porous silicas (HPS) by using a P123/cosurfactant/1,3,5-trimethylbenzene/water four-component microemulsion system. The influence of different diols (i.e., ethanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentadiol, and 1,6-hexanediol) as cosurfactants on the synthesis of HPS was systematically investigated. Among the obtained mesoporous silica materials, the HPS materials with pore structures of disordered-SBA-15-type (Dis-SBA-15) together with mesocellular foams (MCFs) could be clearly identified from the TEM images when using ethanediol, 1,3-propanediol, or 1,4-butanediol as the swelling agent of P123 in the initial synthesis environment, while MCFs were the main phases as using 1,5-pentadiol and 1,6-hexanediol. The results showed that those shorter chain diols with carbon number from 2 to 4 (involving ethanediol, 1,3-propanediol, and 1,4-butanediol) could more easily swell the P123 micelles compared with the longer chain diols (1,5-pentadiol and 1,6-hexanediol). Consequently, HPS materials with large pore volumes (up to 1.48 cm3 g−1) were successfully prepared by the oriented role from the templates of the swollen P123 micelles and TMB/P123 microemulsions. This approach provides a novel pathway for the facile synthesis of HPS materials with large pore volumes which may be a type of promising candidate for various applications.

We have successfully synthesized hierarchical porous silicas (HPS) by using the micelle/microemulsion templating method in a system of P123/cosurfactant/1,3,5,-trimethlbenze/water four-component microemulsion. The pore structures of HPS consist of disordered-SBA-15-type and mesocellular foams. The cosurfactants (ethanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentadiol, and 1,6-hexanediol) can act as expanding agents to swell P123 micelles, while the oil component of 1,3,5-trimethlbeneze can form microemulsion droplets with P123 aqueous solution. So the porous structures of disordered-SBA-15-type and mesocellular foams can be templated by swollen P123 micelles and TMB/P123 microemulsion droplets, respectively.Figure optionsDownload as PowerPoint slide