Ring-Opening Metathesis Polymerization of Pyridinonorbornenes Synthesized from 2,3-Pyridynes

Pyridine-containing polymers are promising materials for a variety of applications from the capture of contaminants to the self-assembly of block copolymers. However, the coordinative ability and the innate basicity of the pyridine motif drastically limit the scope of pyridine-based monomers that can undergo living polymerization. For example, processes relying on transition metal catalysts are rarely amenable to controlled polymerizations because of coordination of the pyridine nitrogen to the metal center. Herein, we report the expedient synthesis of a family of pyridinonorbornene monomers via a [4+2] cycloaddition between 2,3-pyridynes and cyclopentadiene. Careful structural design of the monomer allowed the preparation of polypyridinonorbornenes via ring-opening metathesis polymerization (ROMP) with living characteristics. These unusual macromolecules exhibited high Tg and Td. Investigation of the polymerization kinetics and of the reactivity of the chain ends shed light on the influence of monomer coordination on the chain-growth mechanism.