Synthesis and high refractive index properties of poly (thiophosphonate)s

Novel high-refractive-index materials consisting of poly(thiophosphonate)s, which were synthesized by the polycondensation of phenylthiophosphonic dichloride with various bisphenols, were reported. A mixture containing bisphenol, 2-phenylphenol and sodium hydride in dry tetrahydrofuran (THF) was stirred at 60°C for 0.5 h under argon. After cooling to 0°C, a dry THF solution of phenylthiophosphonic dichloride was added dropwise to the reaction mixture over 1 h. The reaction mixture was warmed to 60°C and stirred for 2.5 h. After the reaction, acetic acid and deionized water were added, and the mixture was extracted with CHCl3. The organic layer was washed three times with deionized water, and the solvent was evaporated under reduced pressure. The residue was poured into acetone, and the obtained solid was washed three times with acetone. These polymers exhibit excellent thermal stability, moderate to high glass transition temperatures and high transparency in the visible light region. Furthermore, they achieve high refractive indices of 1.626-1.687 owing to the highly polarizable sulfur and phosphorous atoms in their backbones and relatively high Abbe numbers of 21.3–27.5.