Preparation and Properties of Halogen-Free Flame Retardant and High Refractive Index Optical Resin via Click Chemistry

Halogen-free flame retardant tri(acryloyloxyethyl) phosphate (TAEP) optical resin was prepared using hydroxy ethyl acrylate (HEA) and phosphorus oxychloride and the chemical structure was characterized by Fourier transform infrared spectrometer and proton nuclear magnetic resonance spectrometer. Optical resins mixed by pentaerythritol tetrathioglycolic and TAEP with different S and P contents were obtained via click chemistry curing. The curing performance, thermal stability and flame retardant performance of the optical resins were analyzed by differential scanning calorimeter, thermogravimetric analyzer, and vertical burning tester, respectively. Additionally, the burned residual morphology of samples was investigated by scanning electronic microscopy, and the refractive indices of the optical resins were measured by an Abbe refractometer. The results revealed that increasing S content could improve the refractive indices of the resins; whereas, the flame retardant performances decreased. The optical resins with S content of 2% and P contents of 7.37% had refractive indices of 1.4935 and UL 94 V-0 flame retard level, respectively. The optical resins had good thermal stability and the 5% decomposition temperature reached up to 200.1 °C.