Fast decoloration of spironaphthooxazine bound to a poly(dimethylsiloxane) network

Abstract

Spironaphthooxazine (SNO) was attached to a three-dimensional network of polysiloxane through the allyloxy group on C-7 of the naphthalene ring of SNO, and the photochemical coloration and thermal decoloration behaviors of this material (Film-P) were examined by comparing their properties with those of model SNO having a 7-propyloxynaphthyl group in solution, in a doped polysiloxane film (Film-D), and in a doped PMMA film. For Film-P, the SNO units were connected to a part of the vinyl groups on the Si atoms of a linear polysiloxane by hydrosilylation, and the remaining vinyl groups were bridged by the bifunctional linear polysiloxane possessing two hydrosilyl groups at both ends of the chain. While Film-P containing 1.7 × 10⁻³ mol dm⁻³ of the SNO unit formed a transparent film, Film-D containing more than 1.2 × 10⁻³ mol dm⁻³ could not form a transparent film but segregation of SNO occurred. A transparent Film-D was prepared at 0.54 × 10⁻³ mol dm⁻³ SNO concentration. The decoloration reaction rate of Film-D was faster than those for Film-P, solutions, and PMMA. However, due to the low concentration, the coloration of Film-D was weak. When the concentration of SNO in Film-P was increased 5.7 times, the decoloration rate became 3.6 times faster. Its half-life time was 0.9 s, which is 3.1 times as fast as that of corresponding solution in hexamethyldisiloxane.