Click Functionalization of a Dibenzocyclooctyne-Containing Conjugated Polyimine

A conjugated poly(phenyl‐co‐dibenzocyclooctyne) Schiff‐base polymer, prepared through polycondensation of dibenzocyclooctyne bisamine (DIBO‐(NH2)2) with bis(hexadecyloxy)phenyldialdehyde, is reported. The resulting polymer, which has a high molecular weight (Mn>30 kDa, Mw>60 kDa), undergoes efficient strain‐promoted alkyne–azide cycloaddition reactions with a series of azides. This enables quantitative modification of each repeat unit within the polymer backbone and the rapid synthesis of a conjugated polymer library with widely different substituents but a consistent degree of polymerization (DP). Kinetic studies show a second‐order reaction rate constant that is consistent with monomeric dibenzocyclooctynes. Grafting with azide‐terminated polystyrene and polyethylene glycol monomethyl ether chains of varying molecular weight resulted in the efficient syntheses of a series of graft copolymers with a conjugated backbone and maximal graft density. Click on a stick: Incorporation of a strained cyclooctyne monomer unit within the backbone of a conjugated polymer structure was achieved through Schiff‐base polymerization, thereby resulting in a conjugated polymer backbone that could be subsequently modified with a variety of azide derivatives through strain‐promoted azide–alkyne cycloaddition.