Colloidal lithography for patterning non-planar surfaces

A colloidal lithography method has been developed for patterning nonplanar surfaces. Hexagonal noncontiguously packed (HNCP) colloidal particles 127 nm--2.7 microm in diameter were first formed at the air-water interface and then adsorbed onto the substrate coated with a layer of polymer adhesive. The adhesive layer plays the critical role of securing the order of the particles against the destructive lateral capillary force generated by a thin film of water after the initial transfer of the particles from the air-water interface. The adhesive could either be attached to the substrate or simply be coated on it. Poly(n-butyl acrylate) and poly( n-butyl acrylate-random-N,N-diethylaminoethyl acrylate) brushes were grafted on the substrates via the "graft-from" method using atom transfer radical polymerization (ATRP) or these polymers were simply synthesized separately and coated on the substrates via dip coating. Silicon-containing polymers were also tested as successful adhesives. Several parameters that influence preservation of the order of the particle arrays were examined. The collidal lithography method is robust and very simple to carry out. It is applicable for a variety of surface curvatures and for both inorganic and organic colloidal particles.;Hierarchical structures of colloidal particles were successfully created on substrates with the use of the colloidal lithography method. Coating these substrates with a low energy coating afforded superhydrophobic surfaces. It was also possible to tune the hydrophobicity of the surface by varying system parameters such as interparticle distance between the particles and the nature of the surface coating. The discrete nature of the particles made it possible to predict the wetting properties of the surface.