Synthesis of Sequence-Specific Polymers with Amide Side Chains via Regio-/Stereoselective Ring-Opening Metathesis Polymerization of 3-Substituted cis-Cyclooctene

Highly regio-/stereoregular (trans-head-to-tail) polymers with amide side chains on every eighth backbone carbon were successfully synthesized by ring-opening metathesis polymerization (ROMP) of 3-substituted cis-cyclooctene (3RCOE) using Grubbs second-generation catalyst (G2). Regioregular linear ethylene-acrylamide copolymers were also prepared via hydrogenation of the obtained poly(3RCOE)s. The thermal properties and solubility of the obtained polymers were strongly influenced by the presence of amide hydrogen in the side chains, the presence of unsaturated bonds in the carbon backbone, and the side chain density. The presence of amide hydrogen in the side chains resulted in the formation of crystalline polymers and the lack of solubility of these polymers in common organic solvents. In contrast, the absence of amide hydrogen in the side chains led to the formation of amorphous polymers exhibiting good solubility in common organic solvents, and decreasing values of T_g were observed for amorphous polymers as a result of the saturation of double bonds in the backbone via hydrogenation.