Synthesis of high refractive index polymer with pendent selenium-containing maleimide and use as a redox sensor

A high refractive index polymer was synthesized by the copolymerization of styrene with different functionalized N-phenyl maleimides, phenyloxide (P1), phenylsulfide (P2), and phenylselenide (P3). The effects of the substituent elements, molecular weight and selenium content on refractive indices, thermostability, and the glass transition temperature of the obtained polymers were investigated. The results showed that the refractive index of obtained polymers increased in the order of P3 > P2 > P1. Introducing the maleimide moiety into the polymer side chain improved its thermostablity and enhanced the glass transition temperature. To increase the selenium content, P4 was polymerized with selenium-containing maleimide monomer and 4-phenylselane styrene. An RI as high as 1.869 was obtained for P4 at a wavelength of 633 nm. Furthermore, the redox responsive selenide moiety endowed the selenide functionalized polymers with the property of refractive index transformation under oxidization and reduction conditions, which provided a material with potential application as a redox sensor.