Synergistic and Competitive Adsorption of Hydrophilic Nanoparticles and Oil-Soluble Surfactants at the Oil–Water Interface

Fundamental insights into the interplay and self-assembly of nanoparticles surface-active agents at liquid-liquid interface play a pivotal role in understanding ubiquitous colloidal systems present our natural surroundings, including foods aquatic life, industry for emulsion stabilization, drug delivery, or enhanced oil recovery. Moreover, well-controlled model mixed interfacial adsorption surfactants allow unprecedented nonideal contaminated particle-stabilized emulsions. Here, we investigate such system composed hydrophilic, negatively, positively charged silica oil-soluble cationic lipid octadecyl amine with situ synchrotron-based X-ray reflectometry, which is analyzed discussed jointly dynamic tensiometry. Our results indicate that negatively only adsorb if oil-water covered lipid, indicating synergistic adsorption. Conversely, readily on their own, but compete reversibly desorb increasing concentrations lipid. These further competitive adsorption, an electrostatic exclusion zone exists around adsorbed particles. This prevents molecules this area, leading to decreased surface excess concentration unexpectedly high tension.