Enhancement of thermomechanical properties of sulfur-rich polymers by post-thermal treatment

Abstract

Recently, sulfur-rich polymers have been applied in various fields including energy storage, mercury removal, and infrared (IR) optics. However, sulfur-rich polymers typically exhibit insufficient thermomechanical properties for practical applications. Herein, we systematically investigate the effects of thermal treatment on the thermomechanical properties, represented by the glass transition temperature (T-g) and storage modulus, of sulfur-rich polymers prepared by inverse vulcanization with 70 wt% elemental sulfur (S) and 30 wt% divinylbenzene (DVB). The thermal treatment was conducted at three different temperatures (110, 140, and 170 degrees C) for six different times (1, 2, 6, 12, 24, and 48 h). During the thermal treatment, the thermomechanical properties of poly(sulfur(70)-random-DVB30) [poly(S-70-r-DVB30)] increased owing to the thermal degradation of small molecules, including sulfur oligomers and thermally degraded DVB, which acts as a plasticizer. However, excessive thermal treatment induced a deterioration in thermomechanical properties owing to thermal degradation. By systematic investigation of the thermal treatment, the storage modulus of poly(S-70-r-DVB30) could increase from 3 GPa to 4 GPa.