Photochromic Cotton Fabric Prepared by Spiropyran-ternimated Water Polyurethane Coating

Photochromic materials have drawn growing interesting due to their capability of interconversion under the action of external optical stimulation, allowing diverse potential applications. Herein, we proposed a novel method of preparing photochromic cotton fabric coated by combined l-(2-hydroxyethyl)-3,3-dimethyl-6-nitrospiro [l(2H)-benzopyran-2,2-indoline] terminated waterborne polyurethane. The synthesized photochromic compounds 1-(2-hydroxyethyl)-3,3-dimethyl-6-nitrospiro[1(2H)-benzopyran-2,2-indoline] (SP-OH), were characterized by FTIR spectra, H-1 NMR and ultraviolet (UV) spectrum. The as-prepared spiropyran-terminated water polyurethane (SP-OH/WPU) was characterized via FTIR spectra, ultraviolet (UV) spectrum, SEM and size analysis. The photochromic cotton fabric was featured via FTIR spectra, ultraviolet (UV) spectrum and SEM. In addition, the photochromic properties, thermal stability of as-prepared cotton fabric was tested. The results showed that the photochromic compounds and SP-OH/WPU have been successfully synthesized and the resultant cotton fabric possesses excellent and durable photochromic properties, including noticeable and quick color alteration under UV radiation and fast recovery when exposed to green light. Furthermore, the excellent thermal stability ensured it undergo harsh service environment, which indicated that it is a good candidate for photochromic textile.