Monomer sequencing and microstructural analysis on polymers of dimethyl norbornene dicarboxylate and 7-oxanorbornene dicarboxylic derivatives employing ruthenium catalysts by ring-opening metathesis polymerization

ABSTRACT The physiochemical properties, comonomer sequencing, and regiospecificity of the linkages between monomeric units within homo/copolymers based on 5,6‐di‐substituted norbornene and 7‐oxanorbornene type monomers by ring‐opening metathesis polymerization are reported and correlated to their primary and secondary structural elements. In general, first‐generation Grubbs‐I1 ruthenium catalyst generates polymers with high trans content that exhibits an extended secondary structure with exo,exo substituents, whereas second‐generation Grubbs‐I2 catalyst produces polymers with high cis content that forms tight turns, resulting in a compact structure. Furthermore, I2‐produced polymers exhibit a high level of alternating cis–trans double bonds along their polymeric backbone. In stark contrast, both first‐ and second‐generation Grubbs catalysts display complete reversal in cis/trans selectivity when an oxygen atom is in position‐7 of the norbornene‐ring along with mono‐endo‐substitution in position‐5 or 6, and hence highlighting the importance of stereoelectronic complexation by the catalyst with the next incoming monomer for cis/trans selectivity. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 2477–2501 Homo/copolymers based on 5,6‐substituted norbornene and 7‐oxanorbornene‐type monomers by ring‐opening metathesis polymerization are reported and correlated to their primary and secondary structural elements. In general, a first‐generation Grubbs‐I ruthenium catalyst generates polymers with high trans content that exhibits an extended serpentine secondary structure with exo,exo substituents. In contrast, a second‐generation Grubbs‐II catalyst produces polymers with higher cis content that forms tight turns, resulting in a compact globular structure.