(583d) Influence of Surfactants and Nanoparticles on Desorption Behavior of Nanoparticles at Fluid Interfaces

The behavior of colloidal particles near interfaces holds significant importance across diverse industrial and environmental domains¹ such as emulsion stabilization² and oil recovery processes.³ Understanding energy considerations, particularly the desorption energy of nanoparticles (NPs) at the interface between immiscible fluids is essential in these applications. In addition, the presence of surfactants alters the interfacial properties, potentially influencing the desorption energy required for NPs to detach from the interface. Both surfactants and NPs can stabilize oil-water interfaces and ultimately impact NP desorption behavior at the oil-water interface.

While many studies overlook specific interactions between particles and surfactants, it is notable that surfactants can indeed interact with the surface of NPs, potentially influencing the desorption energy. Hence, careful consideration of the interplay between surfactants and NPs is essential in the study of mixed interfacial systems composed of surfactants and particles. Our research seeks to gain insights into the energy needed to detach the single NP (including homogeneous and amphiphilic NPs) from the oil-water interface in such mixed systems using Dissipative Particle Dynamics (DPD) simulation methods.^4-7 When the NP transitions between two immiscible liquids, the free energy of the system exhibits asymmetry concerning the particle's distance from the interface. It is observed that the presence of surfactants can reduce the energy requirement, whereas the NP layer may lead to a challenge in the movement of a single NP. Regarding the effect of NP type, hydrophilic NPs are favored in the water phase due to their lower desorption energy compared to the significantly higher energy required in the oil phase. In the case of surface anisotropic NPs, the desorption energy level lies between those of homogeneous NPs. This study also explored how the presence of both surfactant and NPs at the interface affects the desorption energy necessary for NP transport to the bulk phase.

A discussion of the computational methodology and its validation will be presented. Our findings on the relationship between surfactants, NPs, and interfacial properties, which are essential for predicting and controlling NP behavior at two immiscible fluid interfaces, will also be discussed.

References

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4. P. Espanol and P. Warren, Europhysics letters, 1995, 30, 191.
5. T. X. Nguyen, S. Razavi and D. V. Papavassiliou, The Journal of Physical Chemistry B, 2024.
6. T. X. Nguyen, S. Razavi and D. V. Papavassiliou, The Journal of Physical Chemistry B, 2022, 126, 6314-6323.
7. T. X. Nguyen, T. V. Vu, S. Razavi and D. V. Papavassiliou, Polymers, 2022, 14, 543.