Jump to main content
Jump to site search
PLANNED MAINTENANCE Close the message box

Scheduled maintenance work on Wednesday 27th March 2019 from 11:00 AM to 1:00 PM (GMT).

During this time our website performance may be temporarily affected. We apologise for any inconvenience this might cause and thank you for your patience.

Issue 36, 2018
Previous Article Next Article

Microscopic details of a fluid/thin film triple line

Author affiliations


In recent years, there has been a considerable interest in the mechanics of soft objects meeting fluid interfaces (elasto-capillary interactions). In this work we experimentally examine the case of a fluid resting on a thin film of rigid material which, in turn, is resting on a fluid substrate. To simplify complexity, we adapt the experiment to a one-dimensional contact geometry and examine the behaviour of polystyrene and polycarbonate films directly with confocal microscopy. We find that the fluid meets the film in a manner consistent with the Young–Dupré equation when the film is thick, but transitions to what appears similar to a Neumann-like balance when the thickness is decreased. However, on closer investigation we find that the true contact angle is always given by the Young construction. The apparent paradox is a result of macroscopically measured angles not being directly related to true microscopic contact angles when curvature is present. We model the effect with an Euler–Bernoulli beam on a Winkler foundation as well as with an equivalent energy-based capillary model. Notably, the models highlight several important lengthscales and the complex interplay of tension, gravity, and bending in the problem.

Graphical abstract: Microscopic details of a fluid/thin film triple line

Back to tab navigation

Supplementary files

Publication details

The article was received on 30 May 2018, accepted on 26 Aug 2018 and first published on 27 Aug 2018

Article type: Paper
DOI: 10.1039/C8SM01117F
Citation: Soft Matter, 2018,14, 7492-7499

  •   Request permissions

    Microscopic details of a fluid/thin film triple line

    T. Twohig, S. May and A. B. Croll, Soft Matter, 2018, 14, 7492
    DOI: 10.1039/C8SM01117F

Search articles by author