Enhanced Adhesion of Elastic Materials to Small-Scale Wrinkles

Abstract

The adhesive properties of a material can be greatly affected simply by wrinkling its surface. We show the importance of selecting the wrinkle feature sizes (amplitude, b; and wavelength, λ) that complement the material-defined length scale related to the adhesion energy and modulus. A rigid circular cylindrical punch patterned with aligned wrinkles ranging in amplitude from 0.5 to 5.0 μm with a fixed aspect ratio of 0.1 is used to characterize the adhesion of elastic films of smooth poly(dimethyl siloxane) (PDMS). The cross-linker concentration used to form the PDMS layers is varied to determine the impact of material properties on wrinkled surface adhesion. The elastic films have an average thickness of 240 μm and the average probe radius is 1 mm, leading to a confined contact scenario. The separation stress and work of debonding are presented for each cross-linker concentration with testing rates ranging over 3 orders of magnitude. For stiffer films (10 wt % cross-linker, E' ≈ 3.00 MPa), small wrinkles (b ≈ 0.5 μm) increase the separation stress by nearly 200% relative to a smooth interface whereas large wrinkles (b ≈ 5.0 μm) are shown to reduce adhesion significantly. A substantial increase in the debonding energy is also observed for these small-amplitude wrinkles contacting stiff materials. No discernible impact of wrinkled surface topography on the adhesion of softer (2 and 4 wt % cross-linker, 0.05 MPa < E' < 0.30 MPa) films is measured.

Functional Polymeric Materials Inspired by Geckos, Mussels, and Spider Silk

“…The most prominent contributions of this approach are made by Crosby and co‐workers that developed nonfibrillar adhesives with a load‐bearing structure that is compliant in the normal direction to the surface, yet comparatively stiff in the loading direction . Alternatively, wrinkling techniques were used to create relatively simple structured surfaces, retaining the design feature to control adhesion by structuring the surface …”

“…[36][37][38][39] Alternatively, wrinkling techniques were used to create relatively simple structured surfaces, retaining the design feature to control adhesion by structuring the surface. [40][41][42][43]…”

Enhanced adhesion of bioinspired nanopatterned elastomers via colloidal surface assembly

“…Alternatively, wrinkling techniques have been explored as a scalable, potentially cheaper production method. Wrinkled surfaces have been shown to increase or decrease adhesion depending on the testing geometry and wrinkle dimensions [14][15][16][17][18]. Ideally, however, scalable methods should not be limited to two-dimensional patterns, as more complex, three-dimensional sub-micrometre structures would enable the fabrication of surfaces with different property profiles [19].…”

Voltage‐induced wrinkling behavior of dielectric elastomer

“…1,2 Wrinkles with regular spatial periodicity are useful in extensive applications, including metrology, 3,4 complex surface patterning, [5][6][7] 3-D mechanical fabrication, 8,9 smart adhesion, 10,11 and optical gratings. 12,13 Wrinkles appear mostly in compliant materials.…”