Conjugated Poly(phenylacetylene) Films Cross-Linked with Electropolymerized Polycarbazole Precursors

In this work, we describe the synthesis and electropolymerization of conjugated substituted polyacetylenes, poly(N-alkoxy-(p-ethynylphenyl)carbazole) or PPA-Cz-Cn with electropolymerizable carbazole side groups to form conjugated polymer network (CPN) films. The phenylacetylene monomer was functionalized with a carbazole group separated by an alkylene spacer. Polymerization of the monomer in solution is accomplished using a Rh catalyst to form a “precursor polymer”. The electrochemical behavior and cross-linking of the carbazole side group was then investigated by cyclic voltammetry (CV) and spectroelectrochemistry. A trend in the redox electrochemical behavior was observed with varying alkyl spacer length between the poly(phenylacetylene) backbone and carbazole side-group. The resulting film combines the electrooptical properties of the conjugated poly(phenylacetylene) polymer with polycarbazole units in a cross-linked electropolymerized film as evidenced by the CV and spectroelectrochemical behavior. This study emphasizes the preparation of polymer materials with mixed π-conjugated species arising from the electrochemical cross-linking of a designed precursor polymer.