Properties of the photochromic latexes based on spiropyran by emulsion polymerization

The latexes based on 2-(3’, 3’-Dimethyl-6-nitro-3’H-spiro[chromene-2,2’-indol]-1’-yl)ethanol(SPOH) were prepared via emulsion polymerization, using a macromolecular surfactant that copolymerized by methyl methacrylate (MMA), butyl acrylate (BA) and acrylic acid (AA). The photochromism of the latexes was characterized by UV-vis spectroscopy. Through the characterization of DLS and SEM, the sizes and morphological of the latexes were studied before and after UV light irradiation. During the thermal fading process, it appeared continuous variable pattern in the emulsion, which was related to the rearrangement of the stimulated latexes to meet the dynamic balance of ionic strength, due to the reversible isomerization of spirogyra.