Peter Zarras

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.

Synthesis of an Isophorone‐Based Nonlinear Optical Chromophore

Abstract The synthesis of a “CLD‐type” nonlinear optical chromophore incorporating the isophorone unit to rigidize the polyene segment is described. The synthesis required seven steps with an overall yield of 17%.

Polycationic Salts V [1]. 15N NMR Spectra of Amines, Ammonium Salt Monomers, and Polymers of Styrene Based Trialkylammonium Salts

Summary. 15N NMR spectroscopy was found to be essential for the detailed characterization of tertiary amines, vinylbenzylammonium salts, and polymers derived from these compounds. It proved important for the characterization of low 2-ionene oligomers and vinylbenzylammonium salts derived thereof as well. The polymers of these novel monomers were also characterized and identified.

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.

Procedure for the Rapid Synthesis of the Monomer 1,4-Bis(chloromethyl)-2-(2-ethylhexyloxy)-5-methoxybenzene

Abstract The alkylation of 4-methoxyphenol with 2-ethylhexyl bromide was accelerated by using potassium tert-butoxide in dimethylformamide. Subsequent chloromethylation occurred quickly using acetic acid as a cosolvent to give the poly[(2-(2-ethylhexyloxy)-5-methoxy-p-phenylene)vinylene] (MEH-PPV) monomer in 61% overall yield on a 2-mol scale.

Methods for estimating the refractive index profile at near infrared wavelengths of polymers for optical waveguides

Methods that successfully predict the refractive index at near-infrared wavelengths of negatively birefringent polymer films for optical waveguide applications are presented. The starting point for these methods is a correlation based on connectivity indexes originally developed by Bicerano for the refractive index of isotropic polymers at visible wavelengths. This correlation is applied to a set of polyimides at near infrared wavelengths with modifications in order to improve its predictive power. The polyimides were synthesized by condensation of monomers to form the precursor poly(amic acid)s followed by imidization in solution. Solutions of the polyimides were then spin coated onto glass substrates and baked to produce films of 2-3 microns in thickness with a variable negative birefringence. The refractive index profiles of these films near 1320 nm were then measured in both the TE- and TM- modes using a prism-coupling technique. The average refractive index of these films was then compared to the prediction generated by the model. The agreement between the predicted and observed values has been sufficient to enable the rapid development of materials for optical waveguides without the need for many rounds of trial-and-error investigation. These techniques facilitate the development of specialized polymers for optical waveguide applications.

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.

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.

Poly(2,5-bis(N-Methyl-N-Hexylamino)Phenylene Vinylene) (BAM-PPV) as Pretreatment Coating for Aerospace Applications: Laboratory and Field Studies

In this study, an electroactive polymer (EAP), poly(2,5-bis(N-methyl-N-hexylamino)phenylene vinylene) (BAM-PPV) was investigated as a potential alternative surface pretreatment for hexavalent chromium (Cr(VI))-based aerospace coatings. BAM-PPV was tested as a pretreatment coating on an aerospace aluminum alloy (AA2024-T3) substrate in combination with a non-Cr(VI) epoxy primer and a polyurethane Advanced Performance Coating (APC) topcoat. This testing was undertaken to determine BAM-PPV’s adhesion, corrosion-inhibition, compatibility and survivability in laboratory testing and during outdoor field-testing. BAM-PPV showed excellent adhesion and acceptable corrosion performance in laboratory testing. The BAM-PPV aerospace coating system (BAM-PPV, non-Cr(VI) epoxy primer and polyurethane APC topcoat) was field tested for one year on the rear hatch door of the United States Air Force C-5 cargo plane. After one year of field testing there was no evidence of delamination or corrosion of the BAM-PPV aerospace coating system.

Second-order nonlinear optical films for alternating polyelectrolyte deposition

This is a preliminary report on alternating polyelectrolyte deposition (APD) with the goal of making electro-optic films at room temperature. By means of the APD method, films were built up layer-by-layer at room temperature by a dipping process. APD requires two complementary polymers, one being negatively charged and the other being positively charged. The polymer in solution is attracted to the solid substrate by coulombic forces to form the next layer on the substrate. For the first time, second-order nonlinear optical (NLO) polymer films were prepared by APD in which both polymers were NLO-active. The cationic polymer contained a side-chain stilbazole chromophore, and the anionic polymer contained a main-chain cinnamoyl chromophore. The intensity of the second harmonic signal generated in the film increased quadratically with each layer for the first twenty layers.