Hyocheol Jung

Multifunctional near‐infrared (NIR)‐responsive materials are essential for advanced anti‐counterfeiting (ACF). Here, we present a highly transparent squarylium (SQ) dye that integrates triple NIR responses—absorption, fluorescence, and photothermal conversion—within a single molecular system. The 2,3‑dihydroperimidine structure enables strong NIR absorption (811–823 nm) and fluorescence (834–857 nm) with > 97% visible transparency (0.1 wt.%) and thermal stability (T _d = 208°C). The dye exhibits ∼13‐fold higher photostability than indocyanine green (ICG) and repeatable photothermal response under 808 nm irradiation. Screen‐printed NIR‐emitting inks on diverse substrates (films, textiles, glass, plastic bottles) show washing/solvent durability and enable QR code authentication under 832 nm excitation, maintaining no visible contrast under daylight. This work establishes a transparent single‐component NIR photonic platform for multimodal, instrument‐assisted authentication of visually imperceptible security patterns through orthogonal optical readout modes.

Self-reporting systems automatically indicate damaged or corroded surfaces via color changes or fluorescence.

Topology control of polymers is critical for determining their physical properties and potential applications; in particular, topologies that incorporate numerous hydrogen bonding (H‐bonding) donors and acceptors along the polymer chains considerably influence the formation of different inter‐ and intramolecular H‐bonding motifs. In this study, the high‐level control of inter‐ and intramolecular H‐bonding is investigated in topology‐controlled poly(glycidoxy carbonyl benzoic acid)s (PGCs). Three types of topology‐controlled PGCs (i.e., linear, hyperbranched, and branched cyclic structures having a similar degree of polymerization) are prepared by introducing aromatic carboxylic acids into the corresponding polyglycidols (PGs) via quantitative post‐polymerization modification with phthalic anhydride. The obtained three types of PGCs demonstrated the high‐level interplay between the inter‐ and intramolecular H‐bonding in polymer chains by exhibiting the pH‐dependent self‐association properties in the solution state and the strong adhesion properties in the bulk state with high transparency. Interestingly, the dramatically enhanced adhesive property by 2.6‐fold is demonstrated by simple mixing of branched cyclic PGC and topology‐controlled PGs to promote the cooperative H‐bonding between polymer chains. The new class of cooperative H‐bonding is anticipated between topology‐controlled polymers to contribute to the development of advanced adhesive and the high potential in biological and biomedical applications due to its excellent biocompatibility.

Wastewater management is of considerable economic and environmental importance for the dyeing industry. Digital textile printing (DTP), which is based on sublimation transfer and does not generate wastewater, is currently being explored as an inkjet-based method of printing colorants onto fabric. It finds wide industrial applications with most poly(ethylene terephthalate) (PET) and nylon fibers. However, for additional industrial applications, it is necessary to use natural fibers, such as cotton. Therefore, to expand the applicability of DTP, it is essential to develop a novel reactive disperse dye that can interact with the fabric. In this study, we introduced a blocked isocyanate functional group into the dye to enhance binding to the fabric. The effect of sublimation transfer on fabrics as a function of temperature was compared using the newly synthesized reactive disperse dyes with different blocking groups based on pyrazole derivatives, such as pyrazole (Py), di-methylpyrazole (DMPy), and di-tert-butylpyrazole (DtBPy). Fabrics coated with the new reactive disperse dyes, including PET, nylon, and cotton, were printed at 190 °C, 200 °C, and 210 °C using thermal transfer equipment. In the case of the synthesized DHP-A dye on cotton at 210 °C, the color strength was 2.1, which was higher than that of commercial dyes and other synthesized dyes, such as DMP-A and DTP-A. The fastness values of the synthesized DHP-A were measured on cotton, and it was found that the washing and light fastness values on cotton are higher than those of commercial dyes. This study confirmed the possibility of introducing isocyanate groups into reactive disperse dyes.