Synergy between the Assembly of Individual PEDOT Chains and Their Interaction with Light

Abstract

A new method for poly (3, 4-ethylenedioxythiophene) (PEDOT) synthesis based on acid-assisted polymerization is proposed, and the optical and structural properties of the obtained material are explored. Special attention is given to the effect of the polar Bronsted acid on the formation of oligomer/polymer chains and their ability to assemble into nanoobjects. By using 1H and 13C NMR spectroscopy (in the liquid and solid state), the formation of PEDOT in a neutral state was proven. Matrix-assisted laser desorption/ionization–time-of-flight, static light scattering, and dynamic light scattering spectroscopies were used to determine the Mw and size of PEDOT nanoobjects. Moreover, we used density functional theory calculations to seek a correlation between the length of the PEDOT oligomer chain and the position of its lowest-energy absorption peak S1. All calculations were performed in concentrated formic acid and compared with calculations in the gas phase. In addition, we demonstrate a correlation between the photoluminescence (PL) from individual PEDOT chains and that from PEDOT chains assembled into nanoobjects. While individual PEDOT chains show four PL peaks, the assembled PEDOT nanoobjects show only one PL peak. Tuning the process of self-assembly for individual PEDOT chains is a promising way to control the properties of a polymer material.