Piercing an interface with a brush: Collaborative stiffening
Physique et Mécanique des Milieux Hétérogènes, UMR 7636 CNRS ESPCI-Paris6-Paris7, ESPCI 10 rue Vauquelin, 75005 Paris, France, EU
Corresponding author: firstname.lastname@example.org
Accepted: 17 May 2010
The hairs of a painting brush withdrawn from a wetting liquid self-assemble into clumps whose sizes rely on a balance between liquid surface tension and hairs bending rigidity. Here we study the situation of an immersed carpet in an evaporating liquid bath: the free extremities of the hairs are forced to pierce the liquid interface. The compressive capillary force on the tip of flexible hairs leads to buckling and collapse. However we find that the spontaneous association of hairs into stronger bundles may allow them to resist capillary buckling. We explore in detail the different structures obtained and compare them with similar patterns observed in micro-structured surfaces such as carbon nanotubes “forests”.
PACS: 45.70.Qj – Pattern formation / 46.70.De – Beams, plates, and shells / 47.61.Fg – Flows in micro-electromechanical systems (MEMS) and nano-electromechanical systems (NEMS)
© EPLA, 2010