The effect of photo irradiation on the refractive index of spirobenzopyran
(SP) polymer was investigated. Spirobenzopyran polymers were prepared by a
radical polymerization using 6-(p-methacryloyloxy-hexyloxyphenyl)carbonylsp
irobenzopyran, styrene, and butylmethacrylate. Films with spirobenzopyran p
olymers showed color change from pale yellow to deep blue upon irradiation
of a monochromatic light of 340 nm. The colored films were bleached either
spontaneously or by light of 580 nm. The refractive index changes of the sp
irobenzopyran polymers were 5 x 10(-4) and 9 x 10(-4) for 20 wt% and 35 wt%
of the spirobenzopyran content, respectively.