Solution/Gelation of Arsenic Trisulfide in Amine Solvents

Arsenic–sulfur solutions were synthesized by dissolving amorphous arsenic trisulfide (a-As₂S₃) in anhydrous amine solvents. Ethylenediamine provided the highest solubility for As₂S₃ and led to optimum gelation behavior. Thus, it was selected as the model system for this study. The emphasis of the study was the identification of the active polymerizing species in the As₂S₃–ethylenediamine solutions. The molecular transformations that occurred during the sol-to-gel and gel-to-glass transitions of fibers prepared from the As₂S₃–ethylenediamine solutions were also examined and correlated to the proposed solution species.