Unveiling thermal treatment effects on the thermomechanical and IR optical properties of chalcogenide hybrid inorganic/organic polymers

Abstract

We report the influence of post-thermal treatment on the thermomechanical and infrared (IR) optical properties of chalcogenide hybrid inorganic/organic polymers. Using 20 wt% of the tricyclopentadiene (TCPD) crosslinker, elemental sulfur was inverse vulcanized into as-synthesized poly(sulfur₈₀-random-TCPD₂₀) (S80T20) and then thermally treated under different conditions. 140 °C for 12 h was found to be optimal for improving both the thermomechanical and IR optical properties. It is due to the increase in crosslinking density after the reduction of unreacted ES and CC bonds in the crosslinker, while thermal degradation and oxidation were controlled. Glass transition temperature, storage modulus (at 25 °C), and mid-IR transmittance (1 mm-thick) values of S80T20 increased from 6.5 to 29.2 °C, 1.5 to 2.0 GPa, and 38.5 to 41.2%, respectively. Such a strategy could also be applied to S/Se chalcogen mixture-based CHIPs, endowing them with potential for IR optical applications.