Controlled Bending of Microscale Au-Polyelectrolyte Brush Bilayers

Free-standing Au-polyelectrolyte brush bilayer objects were fabricated by a facile route based on microcon tact printing and chemical etching. Patterned poly(methacryloxyethyltrimethylammonium chloride) (PMETAC) brushes were grown on a gold-coated silicon wafer, which was etched to produce free-standing hi layer objects. These bilayers, produced with different thicknesses of Au, were imaged by optical microscopy in suspension in water and in NaCl solutions of varying concentrations. The radius of curvature of these objects was used to extract values for the surface stress induced by the brush in salted and salt-free regimes and to investigate the time scale of the brush swelling transition, demonstrating that this technique can be used to probe the mechanical properties of stimulus-responsive brushes.