The Structure and Rheology of Carbon Nanotubes Adsorbed At An Air-Water Interface

Particles of appropriate size and wetability adsorb strongly at gas-liquid and liquid-liquid interfaces and lower the interfacial energy. The ability of particles to stabilize foams and emulsions was well documented by Ramsden and Pickering more than a century ago. The effect of particle shape has, however, remained largely unexplored and unexploited. We hypothesize that the particle shape matters and that rod-like particles will increase the number of particle-particle contacts, leading to the formation of a stronger layer at the interface relative to spheres. To examine this hypothesize, we have chosen carbon nanotubes (CNTs) as a model system given their high aspect ratio (>1000). In this presentation, we will report our recent findings on the microstructure and interfacial rheology of a CNT-decorated interface. The latter is directly related to the mechanical integrity and stability of the interface. Our findings indicate that CNTs adsorb strongly at the air-water interface, leading to a significant increase in surface pressure. The highly compressible nature of an interface also enables the creation of two-dimensional CNT “liquid crystals” by compressing a CNT-decorated interface.