Influence of Surface-Active Agents on the Transport of Nanoparticles through Interfaces*

Investigating the adsorption and desorption energy of nanoparticles (NPs) at oil-water interfaces, particularly in the presence of surfactants and/or NPs, is important for various applications.¹ Both surfactants and NPs have the potential to influence interfacial properties, so that careful consideration of the interplay between surfactants and NPs is essential when studying the free energy of the system for the desorption or adsorption process. Herein, we employed the Dissipative Particle Dynamics (DPD) method^2-4 to calculate the energy needed for single nanoparticle migration, encompassing both homogeneous and amphiphilic NPs (Janus NPs), across the oil-water interface. We considered scenarios involving NPs alone, surfactants alone, and their coexistence. Our results for NPs that traversed between the oil and water phases revealed that surfactants lowered the energy barrier for desorption. However, the formation of an NP layer at the interface reduced NP mobility and at high enough concetration at  the interface resulted in jammimg.  It was found that the creation of a bridge of water (or oil) as the NP moved out of the water phase (or the oil phase) led to deviations from theoretical predicitons of desorption. 

References

1.         S. Kaur and A. Roy, Environment, Development and Sustainability, 2021, 23, 9617

2.         T. X. Nguyen, et al., Polymers, 2022, 14, 543.

3.         T. X. Nguyen, et al. he Journal of Physical Chemistry B, 2022, 126, 6314

4.         T. X. Nguyen, et al., The Journal of Physical Chemistry B, 2024. 128(12), 3016