Three-level hierarchical micro/nanostructures on biopolymers by injection moulding using low cost polymeric inlays

Abstract The industrial interest in the patterning of surfaces at the micro/nanoscale to include functionalities to a variety of objects and parts has considerably increased across a large range of application sectors during the last years. Hierarchical organization of micro/nanometric surface textures makes it possible to mimic biological solutions to provide enhanced functional properties, as for example, hydrophobicity, hydrophilicity, antibacterial activity, optical or chromatic effects, to cite some. Multiple and high accuracy methods for patterning surfaces at the nanoscale have been developed, and some of them have been applied for high volume manufacturing of such hierarchically patterned surfaces with relative success. However, many of those methodologies rely on the use of expensive machinery and moulds, or on complicated and expensive inserts. Therefore, a method using low cost recyclable tooling and process conditions applicable to high volume manufacturing is currently missing. In this work, we present a scalable, low cost method to replicate hierarchical micro/nanostructured surfaces on plastic films, which can be latter used as inlays for injection moulded parts with standard processing conditions. We use this method to demonstrate the feasibility of replicating three level hierarchical micro/nano textured surfaces using recyclable bio-based polymers (of high relevancy in the current plastic pollution context), and we compare the replication results with those obtained in polypropylene. Finally, we characterize various mechanical and wetting properties of the replicated parts to highlight the validity of the replicated micro/nano textured surfaces, regardless of the biopolymers special crystallization characteristics.