Ring Opening Metathesis Polymerization

The central theme of this research is ring opening metathesis polymerization of norbornenes and substituted norbornadienes by well characterized imido alkylidene catalysts of the type MCHRNROR 2 where R, R, and R are some alkyl or aryl groups, or most recently alkylidyne alkylidene rhenium catalysts of the type ReCHRCROR 2. Initially we focused on developing catalysts that would tolerate functionalities such as carbonyl groups. The findings concerning the polymerization of 2,3- bistrifluoromethylnorbornadiene suggested that the polymer was virtually all trans and tactic. It is now believed to be syndiotactic. Such materials are highly polarizable above Tg200 C. A significant fraction of the present effort is being expended toward understanding how this stereoselectivity arises and how it can be controlled by changing the nature of the catalyst.