Ring-Opening\nMetathesis Polymerization of Thianorbornenes

A series of <i>exo</i>-7-thiabicyclo[2.2.1]hept-5-ene-2,3-dicarboximides\nwere synthesized and polymerized using Schrock’s catalyst,\n2,6-diisopropylphenylimidoneophylidene molybdenum(VI) bis(hexafluoro-<i>tert</i>-butoxide). The ring-opening metathesis polymerization\n(ROMP) reactions were found to proceed in a controlled manner, enabling\nchain extensions and tuning of polymer molecular weight. The polymers\nwere characterized using size exclusion chromatography (SEC) as well\nas spectroscopic (NMR, FT-IR), thermal (TGA, DSC), and optical techniques.\nThe physical, chemical, and optical properties of the polymers were\nfound to be affected by the embedded sulfur atoms and the pendant\nsubstituents. Copolymers with norbornene were also synthesized and\ncharacterized. Treatment of a poly(thianorbornene) with potassium\nhydroxide led to ring-opening hydrolysis and afforded a derivative\nthat was soluble in aqueous media.