Inkjet-printable diacetylene (DA) supramolecules, which can be dispersed in water without using additional surfactants, have been developed. The supramolecules are generated from DA monomers that contain bisurea groups, which are capable of forming hydrogen-bonding networks, and hydrophilic oligoethylene oxide moieties. Because of suitable size distribution and stability characteristics, the single DA component ink can be readily transferred to paper substrates by utilizing a common office inkjet printer. UV irradiation of the DA-printed paper results in generation of blue-colored polydiacetylene (PDA) images, which show reversible thermochromic transitions in specific temperature ranges. Inkjet-printed PDAs, in the format of a two-dimensional (2D) quick response (QR) code on a real parking ticket, serve as a dual anticounterfeiting system that combines easy decoding of the QR code and colorimetric PDA reversibility for validating the authenticity of the tickets. This single-component ink system has great potential for use in paper-based devices, temperature sensors, and anticounterfeiting barcodes.

Inkjet‐printed paper‐based volatile organic compound (VOC) sensor strips imaged with polydiacetylenes (PDAs) are developed. A microemulsion ink containing bisurethane‐substituted diacetylene (DA) monomers, 4BCMU, was inkjet printed onto paper using a conventional inkjet office printer. UV irradiation of the printed image allowed fabrication of blue‐colored poly‐4BCMU on the paper and the polymer was found to display colorimetric responses to VOCs. Interestingly, a blue‐to‐yellow color change was observed when the strip was exposed to chloroform vapor, which was accompanied by the generation of green fluorescence. The principal component analysis plot of the color and fluorescence images of the VOC‐exposed polymers allowed a more precise discrimination of VOC vapors.

Owing to their flexible, light-weight and disposable properties, paper-based electronic and sensor systems have gained much attention. Efficient immobilization and patterning of functional materials on paper substrates are critical to device performance. Herein, we report an inkjet printable and photopolymerizable diacetylene (DA) containing microemulsion system that can be readily transferred to paper substrates using a common office inkjet printer. UV-induced polymerization afforded clean formation of polydiacetylene (PDA) supramolecules on paper and the polymer displayed a typical thermochromism. The resolution of the printed PDA images was found to be equivalent to that of conventional black ink. The randomly oriented DA in the oil phase was found to be transformed to self-assembled layered structures upon printing. The printed PDA supramolecules derived from 5,7dodecadiyne-1,12-diol bis[((butoxycarbonyl)methyl)urethane] (4BCMU) displayed a blue-to-red-toyellow color transition upon heating. Thus, the blue colored 4BCMU-derived polymer was converted to a red colored PDA at 100 C and further heating to 180 C resulted in the generation of a yellow colored PDA. Upon cooling to room temperature, the yellow colored PDA became red and a complete colorimetric reversibility was observed between red (30 C) and yellow (180 C). The thermally promoted reversible PDA phase transition was successfully applied to a banknote to demonstrate an application to a potential counterfeit prevention method.

An electrothermochromic paper display composed of colorimetrically reversible polydiacetylenes (PDAs), utilizing screen printing on photopaper and patterning of electrically conductive wires on the reverse side, was developed. Heat generated by passing a current through the wires on the back of the photopaper induced a blue-to-red color transition of the PDA on the front at regions corresponding to the wires. This resulted in the generation of red-colored images, which disappeared when the supplied electric current was removed. The voltage at which the PDAs changed color could be controlled by using structured diacetylene (DA) monomers. A PDA-based seven-segment display has also been developed. By applying voltages, red-colored numeric digits from 0 to 9 can be displayed on the surface of the PDA layer.