The cellulose colloidal particles with good photochromic and photoluminescent performances had been developed in aqueous solution based on a spiropyran-grafted filter paper cellulose (SP–cellulose) in this study. The insoluble filter paper cellulose dramatically became soluble in ethanol after grafting a spiropyran derivative onto its backbone via esterification. During this process, the optical properties of the spiropyran had been successfully inherited. With the aid of ultraviolet and visible light, the obtained SP–cellulose colloidal particles showed light-induced tunability on both photochromism and photoluminescence, corresponding to the significant change of the spiropyran between weak polar ring-closed spiropyran and strong polar ring-opened zwitterionic merocyanine. Based upon this result, the SP–cellulose colloidal particles were finally obtained in water by follow-up dialysis process. In comparison to the pure spiropyran showing poor optical properties in mixed solvent of ethanol/water, the obtained SP–cellulose colloidal particles in water showed good photochromic and photoluminescent performances as well as fine stability. Considering also the raw material of filter paper being cheap and easy to get as well as the facile preparation process of the functional colloidal particles, our experimental results may bring about more promising applications of spiropyran species and water-insoluble cellulose in aqueous medium.
Spiropyran-functionalized graphitic carbon nitride (MCH@g-C3N4) in acidic conditions was prepared for the first time. MCH@g-C3N4 exhibited dual-wavelength fluorescence emission with two distant bands and distinct solvatochromic behavior owing to the different molecular structures of spiropyran. A three-dimensional organic solvent decoder was fabricated for solvent identification based on the emission wavelength and fluorescence quantum yield of MCH@g-C3N4 in different polar solvents. The ratiometric fluorescence sensing of the water content in organic solvent was realized using water to induce the structural change of spiropyran. A solid-phase MCH@g-C3N4/polyvinylpyrrolidone (PVP) nanofiber mat-based sensor was prepared via cospinning MCH@g-C3N4 with hydrophilic PVP. A fluorescent humidity sensor was fabricated using a commercial syringe equipped with a stainless-steel needle (catcher) to obtain the air inside the grain heap, which enabled the accurate location of the sampling spot. The space between the syringe and piston was used as an enclosed sensing space. Thus, a simple, accurate, and intuitive visual colorimetric method for the internal humidity of a grain heap was realized by analyzing the recorded images.
危险品化学品经营许可证（带存储）