(425h) Stabilization of Glycerol/Dodecanol Pickering Emulsions with Surface-Grafted Silica Nanoparticles

The conduct of Pickering interfacial catalysts (PIC) into glycerol/dodecanol nonaqueous biphasic system can significantly promote the reaction efficiency, while the design of optimal catalytic nanoparticles, which will stay farthest at the interface within the reaction process, remains a challenging task. Here by using dissipative particle dynamics simulations, the stabilization of glycerol-dodecanol systems with the addition of different functional silica nanoparticles was investigated. For mimicking the experimental operation, the silica nanoparticle in our study was surface modified by grafting alkyl chains and sulfonic group (catalytic site) for adjusting the emulsifying capability and catalytic performance. By accessing both the thermodynamic and structural properties of the interface systems, we identified the optimal surface modification including the chain length of alkyl chains and the molar ratio between sulfonic and alkyl moieties. In particular, by examining the surface tensions and interfacial contact angle between the nanoparticles and the glycerol/dodecanol interface, we found that the SiO₂-C₃ nanoparticle displayed excellent capacity to stabilize the emulsion with a wide range of alkyl grafting density ranging from 1.0 – 2.2 group/nm², which was confirmed by the experimental result. In addition, the local molecular concentrations in the directions normal to and parallel with the solid particle surface were analyzed. The analysis indicated that the reaction would mostly take place in the glycerol phase close to the interface, and that the chain length of C₃ was appropriate for retaining sufficiently high number densities of both glycerol and dodecanol molecules in the vicinity of the catalytic sites, and thus facilitated the reactions. Finally, the effect of the product yield was conduct, and it was observed that the size of emulsion droplet decreased as increasing the product yield rate. This work provides useful insight from microscopic perspective toward the design of highly efficient PIC process for glycerol/dodecanol reaction.