Balancing Optical Property and Enhancing Stability for High-Refractive Index Polythiourethane with Assistance of Cubic Thiol-Functionalized Silsesquioxanes

To achieve a better balance between the refractive index and Abbe number, the thiol-functionalized polyhedral oligomeric silsesquioxane (POSS-SH) was incorporated as both nanoreinforcement and cross-linking reagent into high-refractive index polythiourethane (PTU). The influences of the POSS-SH on the microstructures and properties of PTU were investigated. It is found that all the nanocomposites exhibited a dense network structure and high structural homogeneity even at the POSS-SH loading up to 10 wt %. Besides great improvements in the thermal stability and mechanical property, the nanocomposite containing 1.5 wt % POSS-SH revealed a slight reduction in the refractive index from 1.6568 for neat PTU to 1.6557 but a significant increase in the Abbe number from 28 to 35, accompanied by excellent optical transparency. These results indicate that the covalent incorporation of bifunctional POSS-SH into the PTU network will be helpful for the rational design of advanced optical and optoelectronic materials.

Automated summary

The study investigated the influence of thiol-functionalized polyhedral oligomeric silsesquioxane (POSS-SH) on the microstructures and properties of high-refractive index polythiourethane (PTU). It was found that incorporating POSS-SH can improve thermal stability and mechanical properties while slightly reducing the refractive index and significantly increasing the Abbe number, maintaining excellent optical transparency.