Lithographic Tuning of Polymeric Thin Film Surfaces by Stress Relaxation

We report a facile soft lithography (SL) technique that allows fabrication of patterned polymeric surfaces with feature height varying between 0 and h₀, using a single stamp. The method relies on the partial relaxation of the applied stress in a viscoelastic polymer thin film imprinted under a transient external load using a flexible stamp. The applicability of the technique is demonstrated for thermosetting (rubbery) as well as thermoplastic (glassy) polymers over a wide range of lateral dimensions. The lateral dimension and the periodicity of imprinted patterns remain identical to that of the original stamp. The method has potential applications in creating templates for performing combinatorial experiments related to wetting and dewetting studies, adhesion, nanotribology, microfluidics, etc.