Inkjet-compatible single-component polydiacetylene precursors for thermochromic paper sensors

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.