Molecular-Level Processing of Conjugated Polymers. 4. Layer-by-Layer Manipulation of Polyaniline via Hydrogen-Bonding Interactions

TLDR

Layer‑by‑layer adsorption of polyaniline onto nonionic polymers is driven by hydrogen bonding and was investigated using poly(vinylpyrrolidone), poly(vinyl alcohol), poly(acrylamide), and poly(ethylene oxide) while varying solution pH and polymer molecular weight. Polyaniline was successfully assembled into multilayer films via hydrogen‑bonded adsorption onto nonionic polymers, producing highly interpenetrated bilayers with 1–4 S cm⁻¹ conductivities and a higher density of loops and tails than electrostatic assemblies, as confirmed by FTIR spectroscopy and conductivity measurements.

Abstract

The molecular-level layer-by-layer processing of polyaniline with a variety of different nonionic water soluble polymers has been demonstrated. This new type of layer-by-layer adsorption process is driven by hydrogen-bonding interactions and has been accomplished with poly(vinylpyrrolidone), poly(vinyl alcohol), poly(acrylamide), and poly(ethylene oxide). FTIR spectroscopy measurements confirm a high level of hydrogen bonding between polyaniline and the nonionic polymer in the multilayer films. The effects of solution pH and polymer molecular weight on the deposition process were investigated. Comparisons with polyaniline films assembled via an electrostatic mechanism with sulfonated polystyrene indicate that the nonionic polymers adsorb onto polyaniline with a greater density of loops and tails and form highly interpenetrated bilayers with a high polyaniline content. The conductivities of these self-assembled multilayer films were found to be on the order of 1−4 S/cm for films doped with methane sulfonic acid. It was also demonstrated that the deposition process could be carried out with mixed solutions of polyaniline and a nonionic polymer.