Ab initio analysis of the local coordination environment of oligomers derived from polymerizing 5-Norbornene-2-carboxylic acid

Detailed ab initio analysis was performed on the local coordination environment of the polymer formed in three polymerization reactions, polymerization of (1) pure exo-Norbornene carboxylic acid, (2) pure endo-Norbornene carboxylic acid and (3) mixture of exo- and endo-Norbornene carboxylic acids. All possible combinations of dimers resulting from endo/exo attack in a diagonal/linear fashion of the monomers were considered. The calculations were extended up to tetramers with the same repeating units as the dimers. From these calculations it was observed that the formation of the most stable isomer has the following preferences (1) exo linkage between monomer units were favored over endo linkage, (2) diagonal linkages between monomer units were preferred over linear linkages and (3) isomers with more exo-Norbornene carboxylic acid repeat units were more stable than isomers with endo-Norbornene carboxylic acid.