Ring-Opening Metathesis Polymerization of Thianorbornenes

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