Synthesis and characterization of thianthrene-based poly(phenylene sulfide)s with high refractive index over 1.8

Highly refractive thianthrene-based poly(phenylene sulfide)s (TPPSs) have been developed. The TPPSs were prepared from 2,7-difluorothianthrene and dithiols, including 4,4′-thiobisbenzenethiol (TBBT), m-benzenedithiol (mBDT), or sodium sulfide nonahydrate based on aromatic nucleophilic substitution reactions, and showed excellent thermal stabilities such as relatively high glass transition temperatures in the range of 143–147 °C and 5% weight-loss temperatures over 430 °C. All of the TPPSs exhibited very high refractive indices reaching 1.8020 along with a high transparency in the visible region and low birefringence in the range of 0.0037–0.0039.