Synthesis and properties of waterborne polyurethane containing spiropyran groups

Fabrication and characterization of multi stimuli-responsive fibers via wet-spinning process

Luminescent fibers have attracted much attention due to their application in smart textiles for anti-counterfeiting, camouflage, fashion designs and so on. However, fibers with single function of luminescent is fail to meet the growing demand of smart textiles. Herein, we develop a multifunctional fiber with quick-responsive reversible photochromic and light-emitting with long afterglow. Doping with rare earth material SrAl₂O₄:Eu²⁺, Dy³⁺ phosphors and photochromic pigments into polyacrylonitrile (PAN) fibers enable by facile wet-spinning process, the properties of photochromic luminescent fibers were experimentally investigated in details. The results make clear that resulting fibers exhibit quick-responsive reversible photochromic properties and can be excited by a wide range of ray from 300 to 450 nm, displaying a wide band with a maximum peak at 525 nm. The photochromic pigments and SrAl₂O₄:Eu²⁺, Dy³⁺ phosphors distributed in fibers evenly and the fibers are stable below 258.76 °C. Persistent luminescent properties of fibers are excellent and the afterglow can last for more than 1 h. The ultimate strength of fibers are more than 1.39 MPa. Comparing with a lot of investigated luminescent fibers, our work to photochromic luminescent fibers show huge potential in anti-counterfeiting, aesthetics fashion designs and so on for smart textiles.

Preparation and analysis of photochromic behavior of carboxymethyl chitin derivatives containing spiropyran moieties

1ʹ-(2-Acryloxyethyl)-3,3ʹ-dimethyl-6-nitrospiro[2 H-1-benzopyran-2,2ʹ-indoline] (SPA) was synthesized and grafted onto a water-soluble carboxymethyl chitin (CMCH) macromolecule to prepare a photochromic copolymer (CMCH-g-SPA). The structure of CMCH-g-SPA was characterized by Fourier-transform infrared (FT-IR) spectroscopy, thermogravimetric (TG) analysis, X-ray diffraction (XRD) analysis, water-solubility evaluation, and UV-vis spectroscopy. XRD patterns of CMCH-g-SPA revealed that grafting copolymerization disrupts the CMCH semicrystalline structure, thus improving water solubility. UV-vis spectroscopy results supported the negative photochromic behavior of the merocyanine (MC) form of CMCH-g-SPA (CMCH-g-MCA) present in a water solution of the target copolymer. In addition to high solvent polarity, the intermolecular and intramolecular electrostatic attraction between the indolenine cation and the COO⁻ anion were found to be influencing factors, which stabilize these MC form of spiropyran groups grafted onto CMCH. In a water solution, visible light bleaching was completed over a short period (8 minutes) under artificial visible light irradiation and the thermal coloration reaction, whose rate constant at 25 °C was 4.64 × 10⁻⁴ s⁻¹, which fit the first-order reaction equation. After ten photochromic cycles in water solution, the relative absorption intensity of CMCH-g-MCA decreased by 7.92%.

Light and force dual-responsive waterborne polyurethane in multiple states

Novel SP-WPU presents UV light and force dual-responsive properties in both dispersed state and solid state. The environmental friendly material provides an alternative to extend the application for smart coatings and textiles in industry.

Synthesis of blocked waterborne polyurethane polymeric dyes with tailored molecular weight: thermal, rheological and printing properties

The structure–property relationship of the polymeric dyes with tailored molecular weight including rheological, thermal, and printing properties are mainly investigated.