Preparation of cyclohexanone/water Pickering emulsion together with modification of silica particles in the presence of PMHS by one pot method

Pickering emulsions prepared from cyclohexanone and silica sol with equal volumes have been investigated in this article. The aggregation of particles in the sols at different pHs was mainly attributed to the weak electrostatic repulsion in accordance to the classical DLVO theory. The emulsions stabilized solely by sol particles were unstable to creaming and coalescence after a period of storage, and phase separations were observed at aqueous pH>7. In the presence of PMHS, the emulsion stability increased dramatically, and droplets began to form under alkaline conditions. At pH=11, emulsions stabilized by PMHS and particles inverted from o/w to w/o. The causality was investigated by using Fourier transform infrared (FT-IR) spectroscopy, thermal analysis (TGA and DTG) and ²⁹Si CP MAS NMR to characterize the surface nature of particles around the dispersed droplets. It was summarized that the acid conditions were just contributed to the particle aggregation, and no reaction between PMHS and particles was observed. However, alkaline conditions were tested to be responsible for the chemical grafting of PMHS onto particle surfaces, which increased the hydrophobicity of particles and inverted the type of emulsions from o/w to w/o. As a result, stable emulsions and modified particles were prepared simultaneously by one pot method through ball milling.