David J. Irvin

Progress in using conductive polymers as corrosion-inhibiting coatings

Abstract A general review of the chemistry and corrosion control properties of electroactive polymers will be presented. These polymers are also known as conductive polymers (CPs), and this term will be used throughout this article. This paper will focus on both the synthesis of applicable CPs used for corrosion protection in various environments and their potential benefits over common organic barrier coatings.

Poly(propylenedioxy)thiophene-Based Supercapacitors Operating at Low Temperatures

A mixture of the ionic liquids 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (EMIBTI) and 1-ethyl-3-methylimidazolium hexafluorophosphate (EMIPF6) was formulated. The thermal properties of the 50/50 binary mixture were determined by differential scanning calorimetry and cloud point measurement. No evidence of crystallization or phase separation during cooling at 1°C/min to - 60°C was found. The devices constructed in this study were light weight, flexible, and hermetically sealed. These sealed devices proved effective against electrolyte leakage and performance degradation during temperature cycling. The performance of poly(propylenedioxy) thiophene (PProDOT)-based type I supercapacitors using a 50/50 wt % EMIBTI/EMIPF6 electrolyte mixture was compared to the performance using neat EMIBTI. It was difficult to deposit PProDOT films directly from the ionic liquid mixtures. However, it was possible to deposit PProDOT films from EMIBTI and then assemble and test the devices using the 50/50 mixture. The low temperature performance of the EMIBTI/EMIPF6 supercapacitors was superior to that of the EMIBTI-based supercapacitors, evidenced by the retention of capacitive behavior below -30°C. The high temperature performance of the EMIBTI/EMIPF6 supercapacitors was nearly as good as the EMIBTI-based supercapacitors with 10% loss after 10,000 cycles at 70% depth of discharge at 60°C.

Electrochemical Deposition of a New n-Doping Polymer Based on Bis(thienyl)isopyrazole

A novel donor-acceptor polymer based on thiophene and isopyrazole has been prepared for use in n-doping applications. Nonpolymerizable monomer radical cations appear to be the predominant oxidation product, resulting in a need for extended cycling to produce adequate quantities of polymer for characterization. The electrochemical behavior of the polymer films produced is strongly dependent upon the conditions applied during electrodeposition and on the solvent used during cycling of the films. Cycling to reductive potentials during oxidative polymerization in acetonitrile was necessary to produce a polymer film capable of n-doping, likely resulting from a need to establish pathways for cation migration. The neutral polymer undergoes oxidation to the p-doped form at ca. 2000 mV vs Ag/Ag + in propylene carbonate and reduces back to neutral at ca. 0 mV. Conversion of the neutral polymer to its n-doped form involves reductions at -700 and -1300 mV, with reoxidation at -800 and -200 mV to return to the neutral form of the polymer.

Synthesis and characterization of chiral conjugated polymers for optical waveguides

In the pursuit of new photonic devices, the unique waveguide properties of chiral films made from single-handed helical molecules are under investigation. The synthesis of polymers with a hierarchical structure is the first step. In this paper we present results on the synthesis and characterization of poly(p-phenylenes) (PPPs) and polythiophenes possessing amine and amide chiral side-chains. A regioirregular PPP possessing one chiral side group per repeat unit was prepared. Regioregular PPPs possessing two chiral side groups per repeat unit were also synthesized; however, lower molecular weights were achieved due to steric constraints. The PPPs exhibited total optical rotation that was a function of the concentration of the chiral side group, with 35- per chiral group or 70- per repeat unit. A regioirregular polythiophene was prepared using oxidative polymerization. A molecular structure that leads to helical polymer chains that undergo supramolecular packing in spin-cast films is the goal.