Exploring Factors that Determine Cis/Trans Structure and Tacticity in PolymersPrepared by Ring Opening Metathesis Polymerizations Involving Initiators of the Type Syn and Anti Mo(NAr)(CHCMe2Ph)(OR)2. Observation of a Temperature Dependent Cis/Trans Ratio

摘要

The factors that determine the structure (cis/trans and tacticity) of polymersprepared by ring opening metathesis polymerization (ROMP) Using well-defined initiators of the type Mo(NAryl)(CHCMe2Ph)(OR)2 (Aryl = a substituted aryl group and OR = a variety of alkoxides) have been explored. The main finding is a dependence of cis/trans structure on temperature; at low temperatures (-35 deg C) all cis-polymer is formed and at high temperatures (65 deg C) up to 90% trans-polymers are formed. These results are consistent with formation of cis polymer from syn-alkylidene rotamers and trans-polymer from anti-alkylidene rotamers in