An efficient ring-opening copolymerization of thiiranes with elemental sulfur in the presence of the fluoride anion

Sulfurization of selected thiiranes such as 2-phenylthiirane (styrene sulfide), 2,3-tetramethylenethiirane (cyclohexene sulfide) and 2-(alpha-thienyl)thiirane was carried out, leading to sulfur-rich polymers. The activation of the S-8 molecule was initiated by the fluoride anion (F-) delivered by tetrabutylammonium fluoride (TBAF) dissolved in tetrahydrofuran (THF). The opening of the thiirane ring, followed by the copolymerization process, was initiated by the fluoropolysulfide anions (FSx-) generated in situ. The anionic copolymerizations were carried out under mild conditions, below the floor temperature of S-8 (159 degrees C), and a variable ratio of monomers (thiirane/sulfur) was applied to obtain polysulfides with a diversified sulfur content. Polysulfides were characterized using analytical (elemental analysis, gel permeation chromatography), spectroscopic (Raman spectroscopy, FTIR), and thermal (thermogravimetry (TGA), differential scanning calorimetry (DSC)) methods. Mechanistic interpretation of sulfur transfer in the anionic copolymerization of thiiranes with S-8, in the presence of the fluoride anion, has been discussed.