Single-Wall Carbon Nanotubes as Macroemulsion Surfactant

(a) Toluene (top) and water (bottom) in a test tube
(b) Prior to vigorous mixing
(c) After sonication and shearing
(d) SWNT/water mass ratio of 0.0008, (e) 0.0033, (f) 0.012, and (g) 0.18.

Single-walled carbon nanotubes (SWNTs) are insoluble in either water or oil.  When mixtures of SWNTs, water and toluene are sheared rigorously, macroscopic emulsion of water droplets form in toluene with SWNTs residing at interfaces between water and toluene, acting as a natural “surfactant” or interphase material.  The concept of emulsification via amphiphobicity may find applications in processing nanotubes, compatiblizing immiscible fluids, and creating new macroscopic emulsion materials with unique interfacial and structural properties.

Wang, Hobbie, Langmuir, 19, 3091 (2003).