Reactive Inkjet Printing for Fluorescent Materials Patterning

Abstract

Reactive inkjet printing (RIP) is a unique printing technic that affords patterned functional materials via in-situ chemical reaction on printed area. Combination of inkjet printing technic and in-situ chemical reaction enables convenient patterning of insoluble functional materials. In addition, the RIP approach allows combinatorial synthesis of diverse compounds on a single substrate for high-throughput screening. The first phase of dissertation research focused on in-situ synthesis of stimuli-responsive cyanostilbene derivatives based on RIP strategy. In order to optimize the system, the effect of solvent, temperature, reaction time and substrate were investigated. Inkjet printing of aromatic aldehyde, aromatic nitrile, and base solutions afforded efficient synthesis of a luminescent cyanostilbene derivative DBDCS by an in-situ condensation reaction. The reaction was probed by IR, NMR and TGA analyses and a clean product formation was observed after a 24 h reaction. The luminescent cyanostilbene derivative displayed two different phases (B- and G-forms) depending on the substrate used. The B-form product was obtained when a glass substrate was employed, while the G-form cyanostilbene was produced when the reactive inkjet printing was carried out on a PDMS film. Regardless of the substrate used, the in-situ prepared DBDCS shows vapor-chromic and thermochromic behaviors. Cyanostilbene derivatives library also was fabricated by employing various aromatic aldehydes. Fluorescent materials library also was readily prepared through in-situ condensation reaction of reactive inks. A luminescent conjugated polymer was readily generated by printing of a dialdehyde, a phenylenediacetonitrile, and potassium t-butoxide. The second phase of dissertation research focused on the design of a water compatible reactive ink system that is compatible for an office desktop printer. In order to obtain water compatible reactive ink solutions, an emulsion type and a water dispersible reactive ink systems were developed. Emulsion type reactive inks were achieved by employing oil-in-water type emulsion. The ink solutions were applied to the patterning of a cyanostilbene compound using an office desktop printer. Water dispersible reactive reagents were synthesized by attaching oligo(ethylene oxide) units to the reactive ink components. Oligo(ethylene oxide) substituted reagents were found to readily form stable dispersions in water and were compatible to an office inkjet printer. Inkjet printing of a hydrophilic terephthaldehyde, bis(triphenyl phosphonium salt) and potassium t-butoxide using a common office inkjet printer allowed fabrication of fluorescent poly(p-phenylene vinylene) (PPV) patterns via a Wittig type condensation reaction. The simple and efficient strategies developed in this study should be useful for the fabrication of functional organic materials on solid substrates. Especially, the water compatible reactive ink components should find great utility in the large area patterning of functional organic materials using a conventional office inkjet printer.