Synthesis of colorless and high-refractive-index sulfoxide-containing polymers by the oxidation of poly(phenylene sulfide) derivatives†
Abstract
Highly refractive, thermostable, and transparent poly(phenylene sulfide) (PPS) derivatives partially including SO bonds were reported. The polymers were prepared by m-chloroperbenzoic acid (mCPBA) oxidation of the corresponding PPS derivatives, affording sulfoxide or sulfone-containing polymers with high oxidation selectivity. After the oxidation, the transparency and glass-transition temperature (Tg) of the polymers enhanced while maintaining their high refractive indices (nD = 1.66–1.71), owing to the introduction of rigid sulfoxide/sulfone moieties. This bleaching of the bulk films was due to the loss of the lone pairs on the sulfur atom in the sulfide bonds through the formation of the S
O bonds, which led to a smaller conjugation length and weaker absorption in the near-UV region. From the viewpoint of both molar refraction and molecular volume, incorporating the sulfoxide moiety is the best way to enhance transparency and maintain a suitable Tg with a high refractive index.