A Microphase Separation Strategy for the Infrared Transparency-Thermomechanical Property Conundrum in Sulfur-Rich Copolymers

Abstract

With intrinsic optical and dynamic properties of polysulfide chains, inverse vulcanized copolymers have demonstrated immense potential for infrared (IR) optical applications. However, preparing highly IR-transparent sulfur-rich copolymers without sacrificing their thermomechanical properties remains challenging. To overcome the trade-off relationship between IR optical and thermomechanical properties, an in situ microphase separation strategy for the inverse vulcanization of elemental sulfur utilizing self-crosslinkable 1,3,5-trivinylbenzene (TVB) is presented. Even with 80 wt% sulfur content, the microphase-separated TVB-rich domain self-reinforces the copolymer with a noteworthy modulus of approximate to 2.0 GPa and a high glass transition temperature (T-g) of 92.6 degrees C, while still exhibiting outstanding IR optical properties. This work is expected to provide insights into the fundamental structure-property relationships of sulfur-rich copolymers and pave the way for various practical applications.