Organic mixed ion-electron conductive composite films based on polyacrylic acid/polyaniline

Composite materials of polyacrylic acid complexed with polyaniline (PAA/PANI) can be used to form organic mixed ion-electron conductive (OMIEC) films. These are promising candidates for next-generation optoelectronic and energy storage applications. PAA/PANI composite films are connected by blending the amine (NH) groups in PANI with carboxylic groups (COOH) in PAA by an acid-base reaction via strong electrostatic interactions with intermolecular hydrogen bonds. PAA/PANI composite films show that a PAA-rich matrix separates PANI-rich domains. The electrical conductivity of pure PAA film is 0.58 mS cm−1, which is attributed to negatively charged COO− groups, allowing for ion transfer inside the polyelectrolyte. The electrical conductivity of PANI film is 3.56 mS cm−1, which is attributed to the weakly bound electron conductions of the polaron states along delocalized π-orbitals. PAA/PANI composite films with 33 wt% of PANI have higher electrical conductivity (6.57 mS cm−1) due to the high ionic-electronic coupling through the polymer matrix at the interface between phase-separated regions.