Intermolecular Adhesion in Conjugated Polymers

TL;DR

This paper proposes a tunneling-based inter-chain binding mechanism for conjugated polymers, explaining their aggregation behavior and predicting different bound structures for semiconducting and metallic chains.

Contribution

It introduces a novel tunneling mechanism for polymer aggregation and predicts distinct binding patterns based on electronic properties.

Findings

Semiconducting chains form polyacene-like states with binding at every other site.

Metallic chains can bind at each site, including doped states.

Solitons co-localize with binding sites, enhancing stability.

Abstract

Conjugated polymers are observed to aggregate in solution. To account for this observation we propose a inter-chain binding mechanism based on the intermolecular tunneling of the delocalized $\pi$-electrons occurring at points where the polymers cross. This tunneling mechanism predicts specific bound structures of chain that depend on whether they are semiconducting or metallic. Semiconducting chains should form polyacene-like states exhibiting binding at every other site, while (doped) metallic chains can bind at each site. We also show that solitons co-localize with the intermolecular binding sites thereby strengthening the binding effect and investigate the conformational statistics of the resulting bimolecular aggregates.