Enhanced adhesion of bioinspired nanopatterned elastomers via colloidal surface assembly

Abstract

We describe a scalable method to fabricate nanopatterned bioinspired dry adhesives using colloidal lithography. Close-packed monolayers of polystyrene particles were formed at the air/water interface, on which polydimethylsiloxane (PDMS) was applied. The order of the colloidal monolayer and the immersion depth of the particles were tuned by altering the pH and ionic strength of the water. Initially, PDMS completely wetted the air/water interface outside the monolayer, thereby compressing the monolayer as in a Langmuir trough; further application of PDMS subsequently covered the colloidal monolayers. PDMS curing and particle extraction resulted in elastomers patterned with nanodimples. Adhesion and friction of these nanopatterned surfaces with varying dimple depth were studied using a spherical probe as a counter-surface. Compared with smooth surfaces, adhesion of nanopatterned surfaces was enhanced, which is attributed to an energy-dissipating mechanism during pull-off. All nanopatterned surfaces showed a significant decrease in friction compared with smooth surfaces.

Fracture Mechanics Simple Calculations to Explain Small Reduction of the Real Contact Area Under Shear

“…Several authors are focusing on this topic nowadays for its relevance in different scientific areas, which range from adhesive contact of rough surfaces [1][2][3][4][5] to bioinspired [6][7][8] and pressure sensitive adhesives [9][10][11]. A very important topic is the interaction between "adhesion" and "friction".…”

A Maugis–Dugdale cohesive solution for adhesion of a surface with a dimple

“…Interface 14: 20160996 completely detaches. Then, in the second regime (circles), the pull-off happens in partial contact ( point F, figures [3][4][5]. This value ofŝ po is insensitive toŝ 0 , is almost coincident with the JKR value (3.9) and exists if the branch E-F crossesŝ A ¼ 0, as this ensures that the branch can be physically reached.…”

“…Akerboom et al [3] describe a method to build nanopatterned bioinspired dry adhesives using colloidal lithography, which results in elastomers patterned with nanodimples with a wavelength about 10 times the size of the dimple (qualitatively described in figure 1a). Adhesion and friction properties of nanopatterned surfaces with varying dimple depth against a spherical probe counter-surface showed enhancement of adhesion, attributed to reaching full contact and an energy-dissipating mechanism during pull-off.…”

Adhesion Between a Power-Law Indenter and a Thin Layer Coated on a Rigid Substrate

“…The progress of technology allows us today to "design" surface topography down to the nanoscale. Nanopatterned surfaces, with repeating pillars [9] or dimples [10], are nowadays inspiring many researchers to develop pressure sensitive adhesive mechanisms [10][11][12]. The majority of scientific literature has focused on the case of halfspace geometry; nevertheless, the development of microelectromechanical systems (MEMS), anti-wear coatings, microelectronics, pressure sensitive adhesive, multilayer coatings calls for a detailed understanding of the contact behavior of the layered surfaces in presence of adhesion.…”