Photo-reversibility improvement by the control on polarity of polymeric nanoparticles

Incorporation of photochromic compounds into a polymeric matrix through chemical bonding results in an enhancement of photo-activity and stabilization of optical properties. Here, spirooxazineethyl acrylate (SOEA) monomer was synthesized and then copolymerized with other acrylic monomers to give photochromic particles through semi-continuous emulsion polymerization. Nanoparticles consisted of a photochromic core with less polarity and another layer with higher polarity. DLS and SEM results depicted a decrease in particle size with the increase in surfactants to monomers ratio. Studies on photochromic properties by UV-Vis analysis demonstrated a decrease in the absorption intensity despite the increase in SOEA content, due to the enhancement in particle size. The prepared acrylic copolymer particles showed reasonable photo-stability, photo-reversibility and fast photo-responsiveness. As a consequence, acrylic acid functional groups increased the surrounding polarity and resulted in enhanced-stability of merooxazine-isomer and decrement in reversibility to spirooxazines from.

Spirooxazine; Photochromic; Acrylic acid; Photo-reversibility; Nanoparticle