Maleimide Polyacetylene: A Highly Conductive n-Type Polymer

Despite significant interest in conjugated polymers for a wide range of applications in electronics, n-type materials have lagged in performance relative to their p-type counterparts. Polyacetylene is a promising scaffold for addressing this deficiency, as the most conductive conjugated polymer to date when p-doped. However, it displays orders of magnitude lower conductivity in the n-doped state and is not stable under ambient conditions. The systematic introduction of electron-withdrawing groups to the backbone could solve this issue, but few such examples exist. Herein, we address this gap by introducing maleimide polyacetylene (mPA) as a new n-type conjugated polymer. The alternating vinylene-maleimide sequence introduces strongly electron-withdrawing groups to the polyacetylene core while retaining backbone planarity, conferring both ambient stability (LUMO = -4.35 eV) and good conductivity (σ = 22 S/cm) in the n-doped state. The versatile synthetic approach uses ring opening metathesis polymerization to generate nonconjugated precursor polymers with low dispersity and controlled molecular weight. These are then converted to mPA by an unusual base-mediated oxidation that leverages the acidity of the maleimide α-protons.