Origin of adhesion in humid air.
The origin of adhesion in humid air is investigated by pull-off force measurements between nanoscale contacts using atomic force microscopes in controlled environments from ultrahigh vacuum through various humidity conditions to water. An equivalent work of adhesion (WOA) model with a simplified interface stress distribution is developed, combining the effects of screened van der Waals and meniscus forces, which describes adhesion in humid air and which self-consistently treats the contact stress and deformation. Although the pull-off force is found to vary significantly with humidity, the equivalent WOA is found to be invariant. Increasing humidity alters the nature of the surface adhesion from a compliant contact with a localized, intense meniscus force to a stiff contact with an extended, weak meniscus force.
Kim
Doo-In
DI
National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA. dooin.kim@nist.gov
Grobelny
Jaroslaw
J
Pradeep
Namboodiri
N
Cook
Robert F
RF
D000327:Adsorption; D000388:Air; D006813:Humidity; D008956:Models, Chemical; D013499:Surface Properties; D014867:Water / Q000737:chemistry*
D014867:Water