Ring-Opening Metathesis Polymerization of Thianorbornenes

A series of exo-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-tert-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.