The elasticity of a contact line

We calculate the work required to deform a three-phase contact line between two fluid phases and one solid phase using an interface displacement model. This includes the effects of both surface and line tensions. The leading-order dependence on the wavenumber cl of the distortion has been described by Joanny and de Gennes (J. Chem. Phys. 81 (1984) 552). We examine the next-to-leading term, which contrary to expectation is nest the line tension but a quantity of similar magnitude. Cases of divergent line tension are also examined, which demonstrate a regularization exhibiting scaling on a length scale set by q. Negative line tension does not lead to instability of the contact line to small amplitude deformations at ally wavenumber. (C) 1999 Elsevier Science B.V. All rights reserved.