IMPROVEMENT OF THE PROPERTIES OF A FUNCTIONAL ORGANIZED THIN-FILM BY THE INTRODUCTION OF NANOPARTICLES .1. RETARDATION OF PHOTO-ISOMERIZATION RATE OF A SPIROPYRAN-CONTAINING LANGMUIR-BLODGETT-FILM BY THE INCORPORATION OF SIO2 NANOPARTICLES

An investigation of the retardation of the photo-isomerization ability of spiropyran in Langmuir-Blodgett films due to the introduction of S iO2 nanoparticles is reported. The thermal decoloration of merocyanine (PMC) open form to spiropyran (SP) closed form having a long alkyl ch ain was determined at 45 degrees C and 60 degrees C. SiO2 nanoparticle s about 15 nm in diameter were adsorbed from the subphase onto a surfa ce monolayer which consisted of SP mixed with arachidic acid at a mola r ratio of 1:1. LB films composed of such a monolayer showed a retarda tion effect on PMC decoloration and an absorption peak blue shift. The reason for these changes might be attributed to the H-aggregate forma tion of SP molecules caused by the incorporation of SiO2 which restric ted the molecular mobility.