John D. Stenger-Smith

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.

Main-chain syndioregic nonlinear optical polymers. II. Extended Pi conjugation and improved thermal properties

Recent results concerning the synthesis of new main-chain syndioregic nonlinear optical polymers are presented. In particular, the synthesis of polymers with extended pi conjugation in the chromophore and chromophores with improved thermal stability are presented. The nonlinear optical coefficient of several of the polymers and the optical loss at 1.3 and 1.55 μm were measured and are discussed.

High-performance electro-optic polymers for high-frequency modulators

New thermally stable, spin-castable, electro-optic (EO) polymers designed for high frequency optical modulators are reported (the third generation accordion polymers). The softening temperature (the glass transition temperature) is about 240 degrees Celsius, and the upper limit on short term thermal baking stability is about 320 degrees Celsius. The refractive index at 1.3 microns is about 1.73 and fairly birefringent. The second-order nonlinear optic coefficient, d33, of a second generation accordion polymer containing essentially the same chromophore, measured by second- harmonic generation at 1.06 microns, is 120 pm/V (resonance enhanced by the 495 nm absorption). Measurement of the electro-optic coefficient, r33, is in progress. The added thermal stability in these polymers is due to the all- aryl amine electron donor. The molecular topology of the polymer backbone makes it possible for over 85 weight percent of the bulk material to be comprised of EO-active chromophore. The chromophores are configured in a head-to- head mainchain topology. The films are completely amorphous (no microcrystalline scattering sites).

Ionic Liquids in Charge Storage Devices: Effect of Purification on Performance

Ionic liquids have been the subject of study over the past several years and there are quite a few advantages to their use in charge storage devices such as extremely low volatility, high voltage window, and inherently high concentration of cations and anions for charge transport processes1-8. Several ionic liquids are also commercially available. Purity of ionic liquids has been the subject of several publications9-11. The impurities (chloride or water for example) discussed in these publications have a profound effect on the physical properties of the ionic liquids. There is a continuing discussion about the effect of ionic liquid purification on the electrochemical performance of electroactive charge storage devices. In this chapter we examine the effect of column chromatography purification of ethyl methyl imidazolium bis(trifluoromethanesulfonylimide), (EMIBTI) (synthesized by our laboratory on the 100 gram scale) on the performance of a Type I electroactive polymer supercapacitor based upon poly(propylene dioxythiophene) (PProDOT). The EMIBTI was purified on a 100-gram scale preparatory column using 20% acetonitrile and 80% chloroform as the eluting solvent. A detailed analysis was performed on the ionic liquid and impurities such as water, lithium chloride, imidazolium, and other elements and compounds. Best efforts were made to quantify the amounts of these impurities. An attempt was made to correlate the presence or absence of an impurity with electrochemical growth and performance of the Type I electroactive supercapacitor.

Alternating polyanion/polycation second-order nonlinear optical films by aqueous solution deposition

Alternating polyelectrolyte deposition (APD) in aqueous solutions may be used to process nonlinear optical polymers (NLOPs) into noncentrosymmetric ordered films at ambient temperature. Second-order NLOP films were prepared by alternately dipping a substrate into aqueous solutions of a polycation and a polyanion. Polyepichlorohydrin substituted with stilbazolium side-chain chromophore was used as the cationic NLOP. The inactive polyanion was polystyrene sulfonate. Uniform layer to layer deposition is observed as evidenced by a linear increase of UV-Visible absorbance and quadratic increase of second harmonic generated light intensity as a function of film thickness. Films have been uniformly deposited up to 24 bilayers. Films have been further characterized by contact angle measurements, interferometry, and polarized light microscopy. Work is in progress to deposit thicker films of the same quality and to quantify NLO figures of merit.

Accordion polymers for nonlinear optical applications

Abstract The design and synthesis of mainchain chromophore polymers in a syndioregic (head-to-head) configuration is described. Polymers were designed for both electric-field poling and Langmuir-Blodgett-Kuhn (LBK) deposition. LBK deposition gives intrinsically polar films (no E-field poling) as evidenced by nonlinear optical (χ (2) ) properties.

Synthesis and Characterization of bis(Tetrahydrofurfuryl) Ether

Abstract Despite the availability of a large number of alkyl tetrahydrofurfuryl ethers that have a wide range of applications, pure bis(tetrahydrofurfuryl) ether (BTHFE) has not been previously synthesized. Here, we report the synthesis of BTHFE (consisting of the RR, SS, and meso stereoisomers) at greater than 99 % purity from tetrahydrofurfuryl alcohol, using (tetrahydrofuran‐2‐yl)methyl methanesulfonate as an intermediate. Additionally, we demonstrate that BTHFE can be used as a non‐volatile solvent in poly(3,4‐propylenedioxythiophene)‐based supercapacitors. Supercapacitor devices employing solutions of the ionic liquid 1‐ethyl‐3‐methyl‐imidizolium bis(trifluoromethylsulfonyl)imide in BTHFE display similar performances to those prepared by using the neat ionic liquid as an electrolyte, although solution‐based devices exhibit a somewhat higher resistance.

Smart Inorganic and Organic Pretreatment Coatings for the Inhibition of Corrosion on Metals/Alloys

This chapter provides a comprehensive review of both inorganic and organic pretreatment coatings for metals and alloys. Aqueous and nonaqueous corrosion are introduced as well the economic costs associated with corrosion for several industrialized countries. Smart coating strategies currently employed to mitigate corrosion damage are shown as well as future materials and film development. Conversion coatings including chromate and phosphate conversion coatings are discussed as early examples of “smart coatings” for the inhibition of corrosion; and the latest use of lanthanide-based conversion coatings is discussed. The chapter also discusses the corrosion-inhibiting abilities of sol-gel and conductive polymer smart coatings. An examination of new methods to inhibit corrosion highlights self-assembling (SA) molecules, polyelectrolyte (PE) multilayers, the incorporation of “nanocontainers” in a coating formulation, and protective biofilms. These new innovative coatings can provide efficient barrier protection and/or controlled release of corrosion inhibitors, reducing the effects of corrosion via a self-healing mechanism.