Thermoplastic nanoimprint lithography of electroactive polymer poly(vinylidene fluoride-trifluoroethylene-chlorofluoroethylene) for micro/nanoscale sensors and actuators

Thermoplastic nanoimprint lithography has been used for the first time, to the best of our knowledge, as a method for transferring nanoscale patterns to electroactive polymer poly(vinylidene fluoride-trifluoroethylene-chlorofluoroethylene) [P(VDF-TrFE-CFE)]. PVDF, its copolymers, and terpolymers cannot be processed using conventional lithography techniques because of their solubility in most organic solvents and photoresist developers. In this work, line-shaped patterns with widths of 60 to 100 nm were formed in the thermoplastic polymer by thermal compression using a previously patterned and treated silicon (Si) stamp. Annealing of the polymer under compression in a nanoimprinter following imprint resulted in a 10-fold improvement in the surface roughness of the polymer relative to spin-coated layers of P(VDF-TrFE-CFE). Patterning of distinct polymer structures on Si substrates (without residual layer) was achieved for micron scale structures. The processes presented here comprise a basis for the integration of P(VDF-TrFE-CFE) as an active material in nanoscale sensors and actuators.