Nanodiamond-stabilized Pickering emulsions: Microstructure and rheology.

Area of Science:

• Materials Science
• Colloid and Surface Chemistry

Background:

• Pickering emulsions offer an alternative to surfactant-stabilized systems.
• Hydroxylated detonation nanodiamonds (ND-OH) possess unique properties for emulsion stabilization.

Purpose of the Study:

• To investigate the use of ND-OH as stabilizers for Pickering emulsions.
• To characterize the impact of ND-OH concentration on emulsion microstructure and rheology.
• To understand the rebuilding capacity of the emulsion microstructure after shear breakdown.

Main Methods:

• A model system of isopropyl palmitate and water stabilized by ND-OH particles was employed.
• Confocal microscopy was used to analyze emulsion microstructure.
• Rheological measurements assessed emulsion stability, elasticity, and yield stress.

Main Results:

• Increasing ND-OH concentration led to smaller droplet sizes and a denser particle network.
• Emulsion rheology exhibited characteristics of both colloidal gels and surfactant-stabilized emulsions.
• Microstructure recovery after shear was dependent on applied stress, scalable by yield stress.

Conclusions:

• ND-OH are effective stabilizers for Pickering emulsions, enabling control over droplet size and network formation.
• The rheological behavior is governed by interparticle interactions and droplet deformability.
• Yield stress is a critical parameter for predicting microstructure recovery in ND-OH stabilized emulsions.