Pickering Emulsions with Long-Term Stability from Ultrafine Amphiphilic Benzyl-Modified Silica Nanoparticles

Abstract

Pickering emulsions offer superior stability and eco-friendly properties across multiple industries due to solid particle stabilization at oil–water interfaces. However, the design and synthesis of ultrafine nanoparticles capable of stabilizing Pickering emulsions have always been a challenging problem. Herein, ultrafine silica nanoparticles which have a diameter of 20–30 nm, were prepared based on a microemulsion method. The ultrafine silica nanoparticles have excellent dispersion properties in water. The benzyl-modified amphiphilic silica nanoparticles were synthesized by grafting benzyl groups onto the nanoparticle surface using the Pickering emulsion template method after modification with 3-[2-(2-aminoethylamino)ethylamino]propyl-trimethoxysilane. The benzyl-modified silica nanoparticles have excellent interfacial activity, with a three-phase contact angle close to 90°, and can reduce the interfacial tension of the kerosene/water system. The resulting Pickering emulsions stabilized by benzyl-modified silica nanoparticles have excellent long-term stability (stable for at least 200 days). Additionally, benzyl-modified silica nanoparticles can also be used as Pickering emulsifiers for soybean oil, sunflower oil, n-hexadecane, and mineral oil, and they exhibit potential application scenarios in fields such as the food and cosmetics industry, catalytic synthesis, and sustained drug release.