Biostructure-like surfaces with thermally responsive wettability prepared by temperature-induced phase separation...

We present a very efficient and convenient approach to obtain smart biosurfaces by directly replicating biological surface structures. It is realized by a two-step replication process combining regular replica molding and temperature-induced phase separation micromolding (PSmicroM). The negative replicas of biological surface structures using poly(dimethylsiloxane) as the replication material are durable molds for further replication. The positive replicas of biological surface structures are obtained by the second step replication using PSmicroM of poly(N-isopropylacrylamide) aqueous solution, which can be easily carried out just by adjusting temperature. With cold water as good solvent and hot water as nonsolvent, an environmentally friendly PSmicroM process is successfully achieved, and organic solvents for PSmicroM are completely avoided. Our study has demonstrated that the micro- and nanostructures of the lotus leaf and rice leaf can be well replicated using this two-step replication process, and the replicated artificial lotus leaf and rice leaf using poly(N-isopropylacrylamide) exhibit good thermally responsive wettability.