Influence of Side Chain Isomerism on the Rigidity of Poly(3-alkylthiophenes) in Solutions Revealed by Neutron Scattering

TL;DR

This study uses neutron scattering to show how side chain isomerism affects the flexibility of poly(3-alkylthiophenes), revealing that side chain topology influences backbone conformation and potentially impacts electronic properties.

Contribution

It demonstrates that side chain topological isomerism modulates backbone rigidity by affecting π-π interactions and torsional motion in poly(3-alkylthiophenes).

Findings

Side chain branch points increase chain flexibility.

Impeding π-π interactions promotes torsional motion.

Topological isomerism influences molecular rigidity.

Abstract

Using small angle neutron scattering, we conducted a detailed structural study of poly(3-alkylthiophenes) dispersed in deuterated dicholorbenzene. The focus was placed on addressing the influence of spatial arrangement of constituent atoms of side chain on backbone conformation. We demonstrate that by impeding the {\pi}- {\pi} interactions, the branch point in side chain promotes torsional motion between backbone units and results in greater chain flexibility. Our findings highlight the key role of topological isomerism in determining the molecular rigidity and are relevant to the current debate about the condition necessary for optimizing the electronic properties of conducting polymers via side chain engineering.