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Electrochromic polymers (ECPs) have great application potential in flexible displays, and there is an increasing expectation of using green methods to form ECP films. Herein, we propose a modified microemulsion method to prepare cyan/magenta/yellow (C/M/Y) water-dispersed electrochromic polymer nanoparticles (WDEN) systems. Three polymer films (WDECP-C/M/Y) maintain similar electrochemical properties compared to their corresponding organic solvent-based polymer films. It is intriguing that WDECP-C/M/Y exhibit better electrochromic properties in terms of higher cycling stability (97.24%, 95.05%, and 52.84%, respectively) and faster switching time (0.94 s, 1.09 s, and 1.34 s for coloring time, respectively) due to the introduction of nanoparticles. In addition, it can achieve various desired colors by blending the C/M/Y WDEN systems in different ratios. The calculated chromaticity coordinates of the blending polymer films show close values to the experimental observation, and the calculated Δ E * ab values range from 2.6 to 10.3, which may provide theoretical guidance for precisely color control. Finally, large-scale and patterned devices were assembled, which can achieve colored-to-colorless reversible electrochromism at a low driving voltage of 0–1.5 V. This work puts forward a universal and environmentally sustainable strategy to prepare WDEN systems, demonstrating their wide range of applications in display devices and electronic tags. [ABSTRACT FROM AUTHOR]

Ionic hydrogels with designable properties that can detect a broad spectrum of stimuli and have the potential for the preparation of flexible electronic devices are available. However, the incorporation of structurally ameliorated zwitterionic monomers can further enhance the performance of ionic hydrogels and provide them with more functions. In this study, we synthesized a new class of zwitterionic monomers (CNPU) with hydroxyurethane chromophores using a straightforward method and subsequently fabricated a double-network ionic hydrogel, containing as-synthesized zwitterionic monomers and common gelation monomers. The luminescent monomer CNPU provides the hydrogels with fluorescence properties, while the double network structure imparts robust mechanical properties. Furthermore, the abundant hydrogen bond and electrostatic interaction give excellent fatigue resistance and anti-freezing properties (−28.70 °C) to the hydrogel. Ultimately, this hydrogel, characterized by high ionic conductivity (81.08 mS cm−1) and temperature-sensitive sensing, was utilized to develop temperature sensors with remarkable anti-strain interference capabilities (GF = 0.16) and versatile applications including fluorescence positioning and information storage. Given its numerous advantages, this double-network ionic hydrogel exhibits tremendous potential for practical application in flexible sensors. [ABSTRACT FROM AUTHOR]

Metal-free near-infrared (NIR) piezochromic materials (PCMs) have critical applications as sensors and probes, particularly those with high luminescence efficiencies, ultrawide wavelength shifts, and pressure resistances when used in hyperbaric environments. Herein, a rigid-flexible steric blocking strategy is proposed to achieve the desired performance by simply introducing an alkyl carbazole at the periphery of the benzothiadiazole cyanostilbene-based luminophore. The as-synthesised molecule, CzC6BT, exhibits highly efficient deep-red (DR) luminescence in both solution and solid states, with an extraordinary photoluminescence quantum yield (PLQY) of 48.5% in the molten glassy state. The polymorphs Crystal-a (λem = 680 nm, PLQY = 40.1% at atmosphere) and Crystal-b (λem = 670 nm, PLQY = 21% at atmosphere) exhibited ultrawide piezochromism in the DR/NIR region (up to >900 nm), with wavelength shifts of 270 and 263 nm in large tolerable pressure ranges (16 and 13.2 GPa). These properties were significantly superior to those of the control molecule MPBM (164 nm, 10 GPa) without the alkyl carbazole fraction and achieved state-of-the-art NIR PCMs. The rigid-flexible alkyl carbazole wrapped around the dimeric luminophore has important steric blocking effects in hindering the formation of continuous π–π stacking while offering a moderate free volume for molecular rearrangements during compression. Thus, ultrawide NIR piezochromism was observed in CzC6BT, with a limited luminescence quenching effect caused by the enhanced π–π interactions during compression. This work demonstrates that inserting rigid-flexible alkyl carbazoles effectively regulates luminophore stacking, adjusts their response towards compression, and simplifies the rational design of advanced NIR PCMs. [ABSTRACT FROM AUTHOR]

Electrochromic polymer film preparation methods such as spin coating, spray coating, and electrochemical polymerization, are commonly used. At present, developing new film preparation technology is an important aspect in the field of electrochromics. Herein, a continuous in situ self-growing method based on the chemical reaction occurring on the surface of an ITO glass between a metal oxide and organic acid groups was successfully applied to prepare electrochromic polymer films at a mild room temperature. SEM, FT-IR spectroscopy, XPS, and XRD characterization methods were combined to reveal the process and mechanism of film formation. The following notable electrochromic properties were observed: switching time within 6 s, contrast reached 35%, and minimal decrease of stability after 600 cycles. Finally, the patterned films were obtained through the directional growth of polymers in solution. This study provides an effective strategy for designing and preparing electrochromic films by self-growing methods in future applications. [ABSTRACT FROM AUTHOR]