A series of functionalized polynorbornenes containing pendent ether- or ester-bridged poly(aromatic ether) chains were prepared. The ether-bridged norbornene complex was synthesized via cyclopentadienyliron-mediated nucleophilic aromatic substitution reactions. This methodology, combined with that of dicyclohexylcarbodiimide-mediated coupling, allowed for the formation of novel oligomeric aryl ether and ester substituted norbornene complexes. Photolytic demetallation gave the monomers in good yields. Structural identification of the exo and endo isomers of both the metallated and demetallated norbornene derivatives was accomplished using HH and CH COSY NMR techniques. Ring-opening metathesis polymerization (ROMP) of these monomers using RuCl3(hydrate) and (Cy3P)2Cl2Ru=CHPh allowed for the preparation of the functionalized polynorbornenes. Thermal analysis of the resulting polymeric materials demonstrated greater thermal stability as the number of aryl ether groups increased.Key words: aromatic ethers, cyclopentadienyliron, polynorbornene, ROMP, ruthenium catalysts.
Reactions of 5-norbornene-2-methanol with arene cyclopentadienyliron complexes led to the synthesis of two new classes of norbornene monomers with ether or ester bridges ; ring-opening metathesis polymerization of these monomers using ruthenium-based catalysts gave rise to high molecular weight polymers displaying exceptional thermal stability.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.