Beyond Doping and Charge Balancing: How Polymer Acid Templates Impact the Properties of Conducting Polymer Complexes

Abstract

Polymer acids are increasingly used as dopants/counterions to access and stabilize the electrically conducting states of conducting polymers. Beyond doping and/or charge balancing, these polymer acids also serve as active components that impact the macroscopic properties of the conducting polymer complexes. Judicious selection of the polymer acid at the onset of synthesis or manipulation of the interactions between the polymer acid and the conducting polymer through processing significantly impacts the electrical conductivity, piezoresistivity, electrochromism, mechanical properties, and thermoelectric efficiency of conducting polymers. As polyelectrolytes, these polymer acids enable conducting polymer complexes to transport ions in addition to electrons/holes. Understanding the role of the polymer acid and its interactions with the conducting polymer generates processing-structure-function relationships for conducting polymer/polymer acid complexes, which can help overcome challenges that were associated with these materials, such as low electrical conductivity and sensitivity to humidity, and enable the design of conducting polymer complexes with desired functionalities.

Applications of Carboxylic Acids in Organic Synthesis, Nanotechnology and Polymers

“…In 2017, it was reported the study of a series of linear carboxylic acids whit different chain lengths of 6 trans-2-hexanoic acid carbon atoms (CA-6), trans-2-decanoic acid (CA-10), 9-tetradecanoic acid (CA-14), used as halogenfree additives-solvent, considered a sustainable and viable process useful for the production of polymeric films whit optical properties, whit potential application in solar cells. The conclusion of the study showed that increasing the length of the carboxylic acid chain changes the topology of the polymeric film [59].…”

Conducting Polymer Electrodes for Thermogalvanic Cells

“…Therefore, new absorption peaks appear at lower transition energies, in the visible and near infrared (VIS-NIR) parts of the spectrum leading to color changes (37). The electrically conducting state of conducting polymers requires delocalized charges along the conjugated backbone (38). A peculiar case is that of polyaniline where the positive charge is introduced in the π-electronic system by a proton attached on the nitrogen.…”

“…In the case of PEDOT, the conductive state is achieved by redox doping. Here, the role of the PEDOT is to carry the charge of the electrically conductive state of PEDOT (oxidized PEDOT) whereas counter ion balance the charge (38). Figure 2.9 illustrates the oxidative doping of PEDOT.…”

“…The PEDOT chain can be further oxidized by removing two electrons and obtain the bi-polaron defect delocalized on few monomer units and neutralized with two anions. The chemical nature of the counterion can affect the morphology, packing, and conformation of the PEDOT chains; which leads to variation in conductivity levels (38)(39)(40). However, the conductivity of PEDOT does not only depend on the counterion, but also on the fabrication and processing conditions.…”

“…The conductivity of PEDOT strongly depends not only the counter ion but also the fabrication methods and the processing conditions (38)(39)(40). As an example, PEDOT-PSS has conductivities ranging from 0.001 S/cm to 1000 S/cm due to the difference in the process in conditions (10,60,(65)(66)(67)(68)(69) and PEDOT-Tos can have conductivity of 100 S/cm up to 9000 S/cm due to both the difference in counterion and processing conditions (39,40,(70)(71)(72)(73)(74).…”