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Home page > Research topics > Wrinkle morphologies.

Wrinkle morphologies

MSC : Cyprien Gay.

Collaborations Laboratoire InFlux, Université de Mons, Belgique : Hugues Vandeparre (thèse), Christophe Poulard (post-doc, today in Orsay), Fabian Brau (post-doc), Sylvain Gabriele, Pascal Damman.


When compressed along its longer dimension, a slender object tends to buckle. If the object is held only through its ends, only one half-oscillation, of maximal length, is observed. In many situations, the buckling phenomenon is influenced by the presence of another material that limits the amplitude of the slender body oscillations. This then generates wrinkles, such as those observed with the skin.

The morphology of an assembly of wrinkles is sometimes complex and poorly understood. We studied the wrinkles of a Titanium membrane deposited on a thin polymer film. Making substrates with such wrinkles can be an alternative to usual microfabrication techniques for substrates with controled surface roughness.

- In a first work [1], we show that wrinkling patterns at the metallized surface of thin polymer films are sensitive to the sticky or slippery character of the polymer-substrate interface (titanium coating, polystyrene film, and coated silicon substrate). Selective preferred wrinkle orientation and amplitude are achieved. Existing theoretical models are expanded to specific boundary conditions (adhesive vs slippery), and we rationalize these observations.

- In another work [2], we report a simple and flexible method for generating hierarchical patterns from wrinkling instability. Complex features with gradually changing topographies are generated by using the spontaneous wrinkling of a rigid membrane (titanium) on a soft foundation (polystyrene) compressed via the diffusion of a solvent. We show that the morphology of these unreported wrinkled patterns is directly related to the rheological properties of the polymer layer and the geometry of the diffusion front. Based on these ingredients, we rationalize the mechanism for the formation of hierarchical wrinkling patterns and quantify our experimental findings with a simple scaling theory. Finally, we illustrate the relevance of our structuration method by studying the mechanosensitivity of fibroblasts.

- In a third work [3], we studied the various patterns that appear when the deposited PS film is very thin. Bumps appear in new hexagonal array morphologies. We showed that as in adhesive materials (Ghatak et al. 2003), the instability may be due to van der Waals interactions between all three material layers.

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- In another work [4], we wanted to understand the hierarchical wrinkling patterns that appear in very different systems like graphene sheets held on both sides and in curtains that are held on the upper end. When the wavelength is fixed at one end, it evolves in space and follows a power law which depends on the situation: \lambda\propto x^{2/3} for light surfaces without tension and \lambda\propto x^{1/2} for surfaces under tension. To understand the origin of these behaviours, we decomposed these hierarchical structures into a piling of elementary wrinkle bifurcations, which we named "wrinklons". In each situation, we detailed the various contributions (bending, tension, fold) that determine the wrinklon dimension and thus the spatial evolution law for the wavelength, be it for curtains or for graphene sheets.


- [1] Hugues Vandeparre, Julien Leopoldes, Christophe Poulard, Sylvain Desprez, Gwennaelle Derue, Cyprien Gay, Pascal Damman, "Slippery or Sticky Boundary Conditions: Control of Wrinkling in Metal-Capped Thin Polymer Films by Selective Adhesion to Substrates", Phys. Rev. Lett. 99 188302 (2007)

- [2] Hugues Vandeparre, Sylvain Gabriele, Fabian Brau, Cyprien Gay, Kevin Kit Parker, Pascal Damman, "Hierarchical wrinkling patterns", Soft Matter 6 5751-5756 (2010).

- [3] Hugues Vandeparre, Simon Desbief, Roberto Lazzaroni, Cyprien Gay, Pascal Damman, "Confined Wrinkling: Impact on pattern morphology and periodicity", Soft Matter 7 6878-6882 (2011)

- [4] Hugues Vandeparre, Miguel Pineirua, Fabian Brau, Benoît Roman, José Bico, Cyprien Gay, Wenzhong Bao, Chun Ning Lau, Pedro M. Reis, Pascal Damman, "Wrinkling hierarchy in constrained thin sheets from suspended graphene to curtains", Phys. Rev. Lett. 106 224301 (2011) (voir aussi liens vers couverture et reprises)


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