Rheological study of nanoemulsions with repulsive and attractive interdroplet interactions

Nanoemulsions have adjustable transparency, tunable rheology, high stability, and low sensitivity to changes in pH and temperature, which make them interesting for applications such as low-fat and low-calorie foods. In this research, we study model concentrated nanoemulsions which are stabilized by sodium dodecyl sulfate (SDS). To prepare samples in different structural states, semi-dilute nanoemulsions are prepared at 25% droplet volume fraction (phi), after which evaporating the continuous phase at room temperature leads to concentrated nanoemulsions up to 60% volume fraction. Surfactant concentration is also tuned to induce different interdroplet interactions so that concentrated nanoemulsions in repulsive glass, attractive glass, and gel states are achieved. Rheological properties of nanoemulsions with different structural states are comprehensively studied over a volume fraction range. Utilizing the existing predictive models for (nano)emulsion rheology reveals a more satisfactory prediction for repulsive systems than systems with attractive interactions. In addition, a master curve is constructed for storage and loss moduli of nanoemulsions with different interdroplet interactions. The present work offers control over physicochemical properties of nanoemulsions for design of new food products with enhanced quality and functionality. As the potential well between droplets becomes deeper, nanoemulsions show higher and sigma y. By superposition of rheological properties of nanoemulsions, a master curve is constructed for dynamic moduli at different volume fractions and interactions.

Automated summary

This research comprehensively studies the rheological properties of nanoemulsions with different structural states, including repulsive glass, attractive glass, and gel states, by adjusting the droplet volume fraction and surfactant concentration. The study provides a master curve for the storage and loss moduli of nanoemulsions, revealing a more satisfactory prediction for repulsive systems than systems with attractive interactions. The findings offer control over the physicochemical properties of nanoemulsions for the design of new food products with enhanced quality and functionality.