Measuring the three-phase contact angle of nanoparticles at fluid interfaces

Abstract

We report a generic technique to image and study the wettability of spherical nanoparticles adsorbed at liquid surfaces and demonstrate that nanoparticle monolayers can be imprinted at air–water and oil–water interfaces and their three-phase contact angle at the original liquid interface can be determined by an atomic force microscopy scan on a replica of the interface; the technique is tested using four different types of nanoparticles, the smallest one having a radius of 37 nm.