A 15 nm Thick Interlayer for Nanoscale Functional Patterning of Hard and Soft Materials

In many nanostructured materials, such as those for implantation, it would be useful to control surface chemistry (e.g., ligand display) independent of mechanical properties. However, mesoscale heterogeneities native to soft elastomers limit spatial resolution. Here, we design interlayers composed of highly cross-linked 10-200 nm thin-film polydimethylsiloxane (TF-PDMS) for controlled ligand presentation on a range of hard and soft material interfaces. Nanometer-resolution chemical patterns (1 nm wide with a sub-10 nm pitch) assembled on highly oriented pyrolytic graphite (HOPG) are cross-linked to TF-PDMS and transferred to target materials (e.g., glass and soft PDMS) through plasma bonding. In this way, similar ligand densities are presented independently of the native material structure and modulus. We demonstrate that it is possible to leverage the difference in elastic modulus between the TF-PDMS interlayer and a soft PDMS substrate to generate mechanically induced microscale topographical control. Hierarchical nanoscale control over the interface architecture is also used to control the assembly of inorganic nanostructures (high-aspect-ratio gold nanowires) at the interface.