(108b) Surface Properties of Biomimetically Designed Polyelectrolyte Coatings

Controlling interactions and adhesion between surfaces and their environments remains an active challenge in materials science. Desirable properties based on these interactions include surfaces that either demonstrate stickiness to water droplets or ease of shedding droplets, surfaces that resist ice formation or steam condensation are all desirable for various applications. Nature has created numerous materials that might be used as the basis of coatings for these various applications in the surfaces of a number of plants and animals. In the majority of these cases, these superior properties are achieved not with exotic chemistries, but by using a range of textures that enhance the surface properties. For example, the hierarchical nano and microscaled texture used by the lotus leaf to create a self-cleaning, superhydrophobic surface is often cited as an inspiration for artificial surfaces. The wide range of facile techniques available for processing polymers presents an opportunity for the creation of arbitrary surface textures and morphologies. One such example is the “layer-by-layer” (LbL) assembly technique, in which the complexation of oppositely charged polyelectrolytes is directed onto a surface. Using the LbL method films with can be created with a great deal of control as to the placement of film components, which can include nanoparticles or other multivalent materials in addition to polyelectrolytes. Discussed here will be different strategies to create biomimetic polyelectrolyte based coatings that have properties ranging from sticky to slippery with respect to water and other liquids. Our sticky surfaces are a special case of hierarchical texture while our slippery surfaces are created by infusing liquids into a textured surface, replacing the air pockets used in the lotus leaf structure.