Synthesis and characterization of liquid UV-curable-HRI acrylate monomers containing sulfur and aromatic groups

Abstract

High-refractive-index (HRI) liquid monomers containing unsaturated acrylate double bonds possess advantages such as photocurability at room temperature and environmental friendliness. However, introducing acrylate groups often reduces the refractive index of monomers. Although small-molecule sulfur-containing structures have high refractive indices, their pungent odors restrict their applications. In this study, a series of sulfur-containing monomers have been successfully prepared through the optimized combination of sulfur elements, benzene rings, and acrylates. These monomers are in a liquid state, and the refractive index performance has reached an advanced level among photocurable monomers. Furthermore, the optical properties (refractive indices, transmittances), curing properties (double-bond conversion and rate of polymerization), and thermal stability (TGA) of the polymer films have been emphatically investigated. The polymer film has a refractive index of 1.648–1.672 at 589 nm, an Abbe number of 22.20–29.32, a transmittance of >90 % at 550–800 nm, a double-bond conversion of 70–92 %, and a maximum weight-loss rate (T_max) temperature of 354–363 ℃, glass transition temperature (T_g) of 45.91 °C–58.45 °C. It exhibits excellent optical properties, curing properties, and thermal stability, opening up new possibilities for the applications of HRI materials.