Polymerization of Enantiomerically Pure 2,3-Dicarboalkoxy Norbornadienes and 5,6-Disubstituted Norbornenes by Well-Characterized Molybdenum ROMP catalysts
Abstract
Preparing polymers with a regular primary structure is a prerequisite to ultimately controlling the properties of the bulk polymer in a systematic manner. Polymers prepared by ring-opening metathesis polymerization (ROMP) of norbornenes and norbornadienes employing classical metathesis catalysts are rarely regular. In contrast, it has been shown that 2,3-bis(trifluoromethyl) norbornadiene (NBDF6) and 2,3-dicarbomethoxy norbornadiene (DCMNBD) can be ring- opened with 'well-characterized' catalysts of the type Mo(CHCMe2R')(NAr)(OR)2 (R'= Me, Ph; Ar = 2,6-i-Pr2-C6H3) to give highly tactic (>90%) high trans poly (NBDF6) and poly(DCMNBD) when OR = O-t-BU, and high cis poly (NBDF6) and poly (DCMNBD) with a tactic bias of approx. 75% (sigma m)c=0.75) when OR = OCMe(CF3) 2. (The four possible regular structures of polymers of this type are shown in Scheme I.) It has been suggested that high trans poly (NBDF6) and high cis poly (NBDF6) prepared using the initiators mentioned above both have a syndiotactic bias (B and C, respectively) on the basis of the measurement of the value of the relaxed dielectric constant
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 29, 1993
- Accession Number
- ADA272649
Entities
People
- David H. Mcconville
- Gretchen E. Hofmeister
- Richard O'dell
- Richard R. Schrock
Organizations
- Massachusetts Institute of Technology