Study of Synergistic Interactions Between SiO2 Nanoparticles and CTAB in the Presence of NaCl: Relationships with the Formation and Stabilization of Hexadecane-in-Water Emulsions

摘要

Hexadecane/water emulsions were prepared with different mixtures in decreasing ratios (R1, R2 and R3) of silica particles (SiO2) and cetyltrimethylammonium bromide (CTAB) to determine droplet crystallization transitions upon freezing by differential scanning calorimetry (DSC), droplet size distribution, and the rheological properties, in order to study the effect of the [CTAB]/[SiO2] ratio in the formation process and stability of the emulsions. The emulsions were polydisperse and the average droplet size of the emulsions decreased as the [CTAB]/[SiO2] ratio diminished. DSC ageing tests indicated that only the emulsion prepared with R3 (E-R3) presented changes in the average droplet size probably du to a reorganization of the CTAB-SiO2 aggregates at the droplet interface until a well-structured film was developed. Despite that E-R1 and E-R2 presented relatively large nonspherical droplets they were highly stable against coalescence du to the formation of a solid-like interfacial layer.