Preparation and photochromic properties of waterborne polyurethane containing spirooxazine groups

Abstract

Two novel photochromic spirooxazines, SO 1 and SO 3, were successfully prepared and characterized by Fourier transform infrared spectroscopy (FTIR), 1 H-NMR, and mass spectrometry with electrospray ionization (ESI-MS). SO 1 was doped and grafted with waterborne polyurethane (WPU) to afford D 1 -WPU and G 1 -WPU. D 3 -WPU was prepared by doping SO 3 with waterborne polyurethane. FTIR spectra indicated that SO 1 was grafted onto waterborne polyurethane successfully. Scanning electron microscopy proved that spirooxazines of D-WPU can be effectively dispersed in a waterborne polyurethane matrix, and spirooxazines of G-WPU are evenly distributed in the copolymer. The results showed that the light transmittance of modified waterborne polyurethane films decreased compared with pure waterborne polyurethane films, but the water resistance and tensile strength were better. Ultraviolet-visible spectra demonstrated that the thermal stability of spirooxazine derivatives improved significantly after being modified. The fading rate constant of the D 3 -WPU film (k = 0.0079 s -1 ) during the discoloration process decreased 9.77 times in contrast to SO 3 in ethanol, which showed that the thermal stability of spirooxazine in WPU film was obviously enhanced.

Facile development of photochromic cellulose acetate transparent nanocomposite film immobilized with lanthanide‐doped pigment: ultraviolet blocking, superhydrophobic, and antimicrobial activity

“…[ 68 ] The long‐time exposure of those organic photoswitchable dyes to UV irradiation can gradually stimulate their decomposition as well as the loss of their photo‐switching responsiveness, to result in poor photostability and restrict their outdoor applications. [ 69 ] Lanthanide‐doped strontium aluminate exhibits high photostability under UV light, presenting a better fatigue resistance to a repeated coloration–decolouration reversibility process. Lanthanide‐doped strontium aluminate has been applied in various merchandise due to its long‐persistent afterglow properties.…”

Enhanced Coloration/Bleaching Photochromic Performance of WO3 Based on PVP/PU Composite Matrix

“…The peak at 3200 cm −1 correspond to associated hydroxyl group in PVP . The peak at 3300 cm −1 correspond to associated amino group in PU and there were no obvious hydroxyl group . The PVP matrix contains more hydroxyl groups.…”

“…[39] The peak at 3300 cm À 1 correspond to associated amino group in PU and there were no obvious hydroxyl group. [35] The PVP matrix contains more hydroxyl groups. When combined with WO 3 nanoparticles, the amount of associated hydroxyl group become higher, which can be confirmed by the wideness of 3200 cm À 1 peak, suggesting a formation of hydrogen bonding.…”

“…Besides, to get a fast speed photochromic composite foil, a waterborne and non‐hydroxyl resin is required. Typically, waterborne polyurethane (PU), a kind of resin dispersed in water, is nonflammable, nontoxic, unpolluted, high rigidity, strong adhesion, and solvent resistance with non‐structural hydroxyl . Therefore, waterborne PU is an ideal matrix that is cheap, economical and stable as compared with PVA, PVB and PVP.…”

Self‐healable and thiol–ene UV‐curable waterborne polyurethane for anticorrosion coating

“…However, most of the above intrinsic healing systems are solvent‐based coatings, and seldom involve waterborne coating that is more energy saving, environmental friendly and low carbon. With the strict restrictions on the content of volatile organic compounds in various countries' environmental protection regulations, the replacement of solvent‐based coating by waterborne coating has become an inevitable trend in the development of coatings industry . In addition, monomers with special reversible bonds usually involve complex organic synthesis, which is not cost‐effective for practical applications.…”