1999: Nanocapillarity: Wetting of Carbon Nanotubes

It is well documented in the modem literature that the conventional laws of capillarity such as Laplace, Kelvin, and Young-Dupre equations are not adequate when applied to fluids confined by particulate and porous materials. Specifics of interactions of fluids with solid surfaces at the nanoscale are of special engineering importance in view of recent discovery of carbon nanotubes and rapidly growing research in fiber reinforced nanocomposites and other nanotechnologies [1, 2]. We develop a theory of wetting of nanofibers with taking into account the effects of solid surface curvature and liquid-solid apolar and polar interactions [3]. It is shown that a transition from partial wetting to nonwetting may occur as the fiber diameter decreases. In particular, contact angles of water on hydrophobic carbon fibers may vary from 75 ° (plane graphite surface) to 100-130 ° (carbon nanotubes).