Nature has the ingenuity to create a wide range of properties from a few number of elements by using structural diversity. We present in this work surfaces made from polyelectrolyte multilayers that either have very good water pinning properties or water sliding properties. These surfaces mimic the rose petal as well as the surface of the pitcher plant. Both have a textured surface, the rose petal's being one that can strongly pin water and the pitcher plant being extremely slippery when wet. These differences in wettability are based on the difference of the size and density of nanoscaled features on the microscaled texture of the surface.  Polyelectrolyte multilayers are coatings based on the layer-by-layer technique of assembly of oppositely charged polyelectrolytes onto a surface. This assembly of oppositely charged macromolecules can create films and coatings with a range of different properties and functionality. We employ both weak polyelectrolytes and ionomers in our work to achieve this range of textures. The pitcher plant mimic is assembled from weak polyelectrolytes and silica nanoparticles, wet by a lubricant, and achieves water roll off angles of as little as 2 - 3 degrees. The rose petal mimic is constructed by spin coating a film of ethylene-co-methacrylic acid ionomers and polyelecthylene imine. The ionomer is spin coated from a THF solution in which it is not solvated but only dispersed. This allows for the creation of colloidal particles with surface features, possibly created by a dewetting phenomena.

Bioinspired pinning or sliding of water drops on polyelectrolyte multilayer surfaces

248th National Meeting (2014)

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