Dual-Pathway Regulation by Diphenyl Guanidine Enhancing Sulfur Utilization in Sulfurized Polyacrylonitrile Synthesis.

The introduction of vulcanization accelerator (VA) can effectively reduce the amount of sulfur precursor in Sulfurized Polyacrylonitrile (SPAN) synthesis, improving sulfur utilization efficiency and thus promoting the commercial application of SPAN. Nevertheless, the mechanism of VA remains unclear due to the lack of rational experimental design along with effective detection, which hinders the screening of efficient vulcanization accelerators. Using diphenyl guanidine (DPG) as a representative VA, this study employed X-ray absorption spectroscopy (XAS) to detect the bonding interactions through selective excitation of C and S. The modulating role of DPG in the SPAN sintering process has been revealed, and its distinct interaction pathways with PAN and sulfur have been elucidated. DPG facilitates PAN cyclization at a lower temperature, which kinetically promotes C─S bond formation. Meanwhile, sulfur chains are chemically anchored within DPG by attacking the C═N bonds and forming C─Sx -, effectively suppressing high-temperature volatilization and thereby enhancing sulfur utilization efficiency. This study provides insights for the selection of efficient vulcanization accelerators and the rational design of SPAN.