(40d) Adsorption Dynamics of Polymeric Nanoparticles at an Air-Water Interface with the Addition of Surfactants

The self-assembly of nanoparticles (NPs) at an air-water interface is greatly affected by the interaction between NPs and existing components on the interface. Previous studies have been conducted to model the adsorption of NPs onto an air-water interface. However, few studies in the past have quantitatively described the changes of NP adsorption dynamics due to the addition of reagents such as surfactants. In this work, NPs with hydrophobic cores and hydrophilic coronas are made using Flash NanoPrecipitation (FNP) method. We demonstrate that even at a very low concentration, ionic surfactants such as sodium dodecyl sulfate (SDS) and cetrimonium bromide (CTAB) can change the electrostatic potential of both the NPs and the interface, so as to affect the rate of adsorption of NPs at the interface. Quantitative comparison has been carried out to compare this electrostatic interaction energy with the change of adsorption energy derived from the Ward and Tordai model. We have also observed that the variation of NP adsorption due to the ionic surfactants can be eliminated by applying the shield effects of free salts, or by changing the core materials of NPs. Out findings have brought new insights into the fundamental understandings of NP interfacial assembly dynamics.