The adsorption and self-assembly of nanoparticles at fluid interfaces is important in the preparation and design of soft materials such as Pickering emulsions. The interactions of the nanoparticles with the oil-water interface are governed in part by their hydrophobicity and wettability, which can be controlled by tailoring the nanoparticle surface chemical composition. Here, we report studies aimed at characterizing the adsorption of chemically functionalized gold nanoparticles at the toluene-water interface using interfacial tension (IFT) measurements. Gold nanoparticles were functionalized with binary mixtures of alkanethiols terminated in polar (i.e., hydroxyl, amine, or guanidine) and nonpolar (i.e., C8, C10, or C12) functional groups. Our results show that the nanoparticles adsorb at the toluene-water interface to decrease the IFT of the system, with the change in IFT dependent upon the polar group identity, the nonpolar group chain length, and ratio of polar/nonpolar functional groups present on the nanoparticle surface. The results from additional studies performed using optical microscopy, light scattering and zeta potential methods to complement the IFT measurements will also be discussed.

Influence of surface composition on the adsorption of chemically functionalized gold nanoparticles at the oil-in-water interface

ACS Spring Meeting 2021

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