Formation of Films and Photoimages of Pigments by Photoisomerization of Surfactants with a Spiropyran Moiety

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Formations of films and photoimages of pigments by the photoisomerization of surfactants with a spiropyran moiety are examined. Surfactants containing a spiropyrane moiety (SPPEG) were synthesized. Blue film with a photoimage was prepared on a polyester plate by the illumination with UV light of a suspension containing SPPEG, β-type copper phthalocyanine (β-CuPc, C. I. Pigment Blue 15), and FeSO4 under neutral or alkaline conditions. The resolution was of the order of 10, um. No film was formed without addition of FeSO4. Blue (α-CuPc, C. I. Pigment Blue 15), red (C. I. Pigment Red 177), violet (C. I. Pigment Violet 23) and yellow (C. I. Pigment Yellow 55) films and photoimages were also obtained by a similar method. The critical micelle concentrations of SPPEG, the MC form and the complex of the MC form with Fe2+ were measured as were their adsorption isotherm on the pigment particles. The influences of the concentrations of the pigment, SPPEG and divalent metal, and pH on the film growth were discussed. The mechanism of the film formation was estimated as follows : The surfactants are isomerized to the MC form by UV illumination. The MC form forms a complex with Fe2+ ion which results in the loss of their amphiphilicity and desorption of the surfactant molecules from the pigment surface. Such a desorption of the surfactants leads to the deposition of pigment particles onto the substrate to form a film.
Japan Society of Colour Materialの論文