Solid-like elastic behavior of nanosized concentrated emulsions: Size-dependent Young's and bulk moduli

Concentrated emulsions with volume fractions exceeding the critical value have diverse applications in foods, cosmetics, coatings, and pharmaceuticals. They have a jammed structure and tend to exhibit a solid-like behavior. Unfortunately, the mechanical properties of monodisperse concentrated emulsions are challenging to study by experiments or simulations because of thermodynamic instability and droplet coalescence. A mesoscopic simulation method is employed to study the mechanical properties of the concentrated emulsion. Knowledge of the microstructure and interdroplet interaction among monodisperse droplets is not a prerequisite. Effects of the volume fraction (phi), droplet diameter (D), and interfacial tension (sigma) on Young's modulus (E) and bulk modulus (K) are investigated systematically. For phi < phi(c), Young's modulus is absent and the bulk modulus rises with increase phi. For phi > phi(c), both Young's and bulk moduli are found to grow with increasing phi and sigma. However, these solid-like properties become more prominent as D is decreased. On the basis of the interfacial energy per unit volume, our simulation results can be well represented by the relations E similar to phi(0.13)(phi-phi(c))(1.55)(sigma/D) and K similar to phi(1.06)(phi-phi(c))(0.15)(sigma/D). Moreover, the relationship for soft materials E = 3 K(1 - 2 nu) is satisfied. The Poisson's ratio (nu) is very close to 0.5 but still decreases slightly with increasing phi. (c) 2023 Elsevier B.V. All rights reserved.

Automated summary

Concentrated emulsions with volume fractions exceeding the critical value display solid-like behavior and have diverse applications. However, it is challenging to study the mechanical properties of monodisperse concentrated emulsions due to thermodynamic instability and droplet coalescence. A mesoscopic simulation method is employed to investigate the effects of volume fraction, droplet diameter, and interfacial tension on Young's modulus and bulk modulus.