Fabrication and replication of re-entrant structures by nanoimprint lithography methods

In this work, the authors present and demonstrate a simple method to fabricate and mass replicate re-entrant structures. The method consists of the direct imprinting of polymer mushroomlike microstructures produced by a combination of photolithography and nickel up-plating process. In particular, they have studied the conditions to generate highly robust mushroomlike topographies and their topographical impact on the replication process. They discuss all the imprinting conditions suitable to replicate such topographies using both ultraviolet light assisted nanoimprint lithography (UV-NIL) and thermal NIL methods in two polymer films, poly(methyl methacrylate) and polypropylene, and a hybrid (organic–inorganic) UV light curable photoresist, namely, Ormocomp. Re-entrant topographies have been widely studied for liquid/oil repelling and dry adhesive properties, whereas in their experiments, they have proved evidence for their amphiphobic potential.