Creating thin film compositional polymer libraries using electrospray deposition

Electrospray deposition (ESD) enables the growth of polymer thin films in a precise and continuous manner by the delivery of sub-micron droplets of dilute polymer solutions to a heated substrate. By combining ESD with programmable motor control and gradient solution pumping in a first-of-its-kind user tool at the Center for Functional Nanomaterials at Brookhaven National Laboratory, we show the ability to create one or two-dimensional compositional gradient nanoscale films via ESD. These capabilities make it possible to construct thin film multicomponent “libraries” on a single substrate to rapidly and systematically characterize composition-dependent properties, in particular, thin films involving homopolymer and block copolymer (BCP) blends. We report the design, construction, and validation of a gradient ESD tool which allows users to carefully control the jet stability, flow composition, spray position, and substrate temperature. Paired with synchrotron small angle X-ray scattering (SAXS), this tool forms an integral part of a new platform for high-throughput, autonomous characterization and design of self-assembling polymer blends as well as functional soft materials more generally.