Preparation of 2,5-bis(methylallyl thioester)-thiadiazole with high refractive index and its coatings

New high refractive index monomer of 2,5-bis(methylallyl thioester)-thiadiazole (BMATETDZ) containing thioester and dithiazole was synthesized by a one-step condensation reaction with methyl acryloyl chloride and 2,5-dimercaptothiadiazole (DTD). N–N=(C), C=O, and C–S with high molar refraction groups were introduced into the structure of BMATETDZ. FTIR and 1 H NMR were used to characterize the molecular structure of BMATETDZ. The refractive index of BMATETDZ was 1.661. The coatings of poly (2,5-bis(methylallyl thioester)-thiadiazole) (C-PBMATETDZ) on polyethylene terephthalate (PET) film were prepared by photopolymerization under UV irradiation. The C-PBMATETDZ coatings exhibited better comprehensive properties with high refractive index, high hardness, good adhesive force, excellent thermal stability, and high transparency in range of 200–900 nm. Graphical Abstract