Comparison of structural and mechanical properties between water-in-oil high internal phase Pickering emulsions stabilized with surface-modified spindle-shaped and amorphous TiO2 particles

• Published in: Colloids and surfaces. A, Physicochemical and engineering aspects Vol. 707; p. 135940
• Main Authors: Kim, YeRin, Hwang, Jun Pil, Choi, SeoYoung, Choi, SooBin, Lee, EunSuk, Kwon, Sun Sang, Kim, Tae Hoon, Cho, Yong Jae, Kim, KyuHan
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 20.02.2025
• Subjects: cosmetics; droplet size; droplets; drugs; Emulsion stability; hydrophobicity; oils; Rheological properties; Spindle-shaped particles; stearic acid; TiO2 particles; titanium dioxide; viscoelasticity; water solubility; Water-in-oil high internal phase emulsions; Water-in-oil high internal phase emulsions; Emulsion stability; TiO2 particles; Spindle-shaped particles; Rheological properties
• ISSN: 0927-7757
• DOI: 10.1016/j.colsurfa.2024.135940

Water-in-oil high internal phase Pickering emulsions (W/O HIPPEs) are known for their polyhedral droplet structures and viscoelastic properties, attributed to their high dispersed phase volume fraction. These emulsions are particularly useful for encapsulating water-soluble compounds while minimizing the use of the oil phase, making them highly desirable for applications in industries such as pharmaceuticals, cosmetics, and food. While most studies have focused on stabilizing oil-in-water (O/W) HIPPEs using amorphous TiO2 particles, this study, for the first time, investigates the stabilization of W/O HIPPEs using TiO2 particles modified with hydrophobic stearic acid to enhance stability. Additionally, we explore the critical role of particle shape—comparing spindle-shaped and amorphous particles—on the interfacial stability and mechanical properties of W/O HIPPEs. Through detailed analysis of droplet size, particle behavior at the interface, and the rheological properties of the emulsions, we demonstrate the versatility of these TiO2 particles in stabilizing HIPPEs with tunable internal structures. This research provides a foundation for the customizable design of HIPPE formulations, paving the way for targeted applications across a wide range of industries. [Display omitted] •TiO2 particles are surface modified with stearic acid to enhance their interfacial activity.•For the first time, we successfully achieve stable W/O HIPPEs using surface-modified TiO2 particles.•We confirm that the interfacial behavior of colloidal particles varies significantly depending on their shape.•We compare the interfacial stability and mechanical properties of W/O HIPPEs stabilized by spindle-shaped versus amorphous particles.