High-Temperature Melt Stamping of Polymers Using Polymer/Nanoporous Gold Composite Stamps

Parallel lithographic deposition of polymers onto counterpart substrates is a widely applied surface manufacturing operation. However, polymers may only be soluble in organic solvents or are insoluble at all. Solvent evaporation during stamping may trigger hardly controllable capillarity-driven flow processes or phase separation, and polymer solutions may spread on the counterpart substrates. Solvent-free stamping of melts prevents these drawbacks. Here, a stamp design for the deposition of melts is devised, which intrinsically circumvents ink depletion. The stamps' topographically patterned contact surfaces with protruding contact elements contacting the counterpart substrates consist of a nanoporous gold layer with a thickness of a few micrometers. The nanoporous gold layer is attached to a molten polymer layer, which is support for the nanoporous gold layer and ink reservoir at the same time. The nanoporous gold layer in turn stabilizes the topography of the stamps' contact surfaces. As examples, arrays of submicron microdots of polystyrene and poly(vinylidenefluoride-trifluoroethylene) (PVDF-TrFE) are manufactured. The P(VDF-TrFE) microdots are partially crystalline, ferroelectric, and can be locally poled. It is envisioned that the methodology reported here can be automatized and may be extended to functional low-molecular-mass compounds, such as active pharmaceutical ingredients.