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Novel Galvanic Corrosion Inhibitors: Synthesis, Characterization, Fabrication and Testing
Abstract
In materials strategy, the Department of the Navy is the first to consider the development of novel anti-corrosion inhibitors. Thus we proposed to develop novel corrosion inhibitors based on polymer metallocomplex composite materials. These new materials can cut off the electron transfer path via the polymer metallocomplexes. Bipyridine-based polymerizable ligand monomers were synthesized starting from 4,5-diazatluoren-9-one (1). The copolymers of the polymerizable methacrylate-type monomer with styrene, methyl methacrylate, and butyl methacrylate have strong blue-light- emitting properties. Amphiphilic tris(2,2'-bipyridine)ruthenium-cored star polymers of polystyrene and poly(N-isopropylacrvlannide) were found to self-assemble into core-shell micelles in which the ruthenium ions are located on the interface between core and shell. The amphiphilic star-shaped metallopolymer with longer PNIPAM blocks formed micro-sized aggregates at high concentration To prepare ligand-endfunctionalizedd polymers, we also synthesized ligand-functionalized initiators. We also synthesized the nanoparticles of zeolite Y (of various chemical compositions) using various techniques such as the addition of organic additives to conventional zeolite Y synthesis mixtures to suppress zeolite Y crystal growth; nanoporous slilcate host materials of up to 30 nm pore diameter, using poly (alkylene oxide) copolymers, which when removed will yield a mesoporus material; and investigated the zeolite Y/Nannnroas composite materials as hosts for corrosion inhibitors.
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This was the discovery that "plastics can corrode" under galvanic conditions and was a factor that led to change in aircraft design. (faudree effect, フォードリー結果) 電気化学的過程とグラファイト/ポリイミド複合材料の関係) Research results are used for the safety and reliability of commercial airplanes, automobiles, and boats. ABSTRACT: The possibility of galvanic action between graphite composites and metals has long been recognized. Recently, at General Dynamics Fort Worth Division, it was discovered that imide-linked
resins can degrade under certain laboratory conditions involving the galvanic process. The
galvanic coupling was found to cause hydroxyl ions to be formed at the gaphite cathode, hence
attacking the O-C-N bond of the polyimide ring structure. Degradation was found ro initiate at
exposed graphite sites at salt water/fuel or salt water/stagnant air interfaces. The phenomenon was
found to occur in bismaleimides (BMI), condensation polyimides, triazines, and blends thereof.
Standard galvanic protection schemes were demonstrated to be effective in preventing degradation,
particularly when proper treatment of the composite was provided.
Note: Since this was the first time polymer degradation (corrosion) by glavanic action was mentioned in the literature, that "plastics can corrode" these results have been referred to as "faudree effect" by workers in the aerospace industry and peer-reviewed publication.
Polyimides reinforced with graphite fibers possess superior mechanical properties in the 121-288°C(250-550°F) temperature range compared to their epoxy counterparts. Polyimides, such as bismaleimides (BMI), are susceptible to hydrolysis which results in physical degradation of the composite. A situation where hydrolysis can occur in a service-type environment has been identified. The situation is a graphite fiber/bismaleimide composite coupled to a metal such as aluminum in a sump-type environment. If the aluminum corrodes, the composite, since it is electrically coupled to the metal, becomes the cathode. Water reduction in the presence of oxygen occurs at the cathode which leads to the formation of hydroxyl ion which attacks the bismaleimide resin. This study has identified the factors required for degradation and the effect of different variables on the reaction rate. Temperature was found to be the greatest reaction accelerator and unexposed composite edges present the best method of slowing the reaction. It was also found that the galvanic current correlates to the amount of degradation observed in the composite as well as the rate of metal corrosion.
Amphiphilic tris(2,2′-bipyridine)ruthenium-cored star-shaped polymers consisting of one polystyrene block and two poly(N-isopropylacrylamide) blocks were prepared by the “arm-first” method in which RAFT polymerization and nonconvalent ligand–metal complexation were employed. The prepared amphiphilic star-shaped metallopolymers are able to form micelles in water. The size and distribution of the micelles were studied by dynamic light scattering and transmission electron microscopy techniques. Preliminary studies indicate that the polymer concentration and the hydrophilic poly(N-isopropylacrylamide) block length can affect the morphologies of the formed metal-interfaced core–shell micelles in water. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4204–4210, 2007
Polyimides were synthesized from bicylic dianhydrides and diamines. The bicyclic monomers used were bicyclo[2.2.2]oct‐7‐ene‐2,3,5,6‐tetracarboxylic dianhydride (BCDA), 1,4,7,8‐tetrabromobicyclo[2.2.2]oct‐7‐ene‐2,3,5,6‐tetracarboxylic dianhydride, and 1,4,7,8‐tetrachlorobicyclo[2.2.2]oct‐7‐ene‐2,3,5,6‐tetracarboxylic dianhydride. The diamines used were benzidine, 4,4‐diaminodiphenyl ether, 4,4‐(hexafluoroisopropylidene)dianiline and 4,4‐(1,4‐phenylenedioxy)dianiline. Each dianhydride was polycondensed with each of the diamines in N‐methyl pyrrolidinone (NMP) at elevated temperatures. The polymers were characterized by means of IR and C nuclear magnetic resonance (NMR) spectroscopy, solubility and thermal analysis such as differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Thermogravimetric analysis studies indicate that the polymers were all stable to above 320°C. Most of the polymers were found to be soluble in highly polar solvents such as dimethyl sulfoxide (DMSO), NMP, dimethyl acetamide (DMAc) as well as concentrated sulfuric acid. Thermal studies of the behavior of the bicyclic components of the polyimides were carried out by the use of low molecular weight imide dimers. The results obtained indicate that the bicyclic ring system undergoes a thermal retro Diels‐Alder reaction thus separating into two fragments.
Bipyridine-centered poly(N-isopropylacrylamide) polymers with controlled molecular weight and low polydispersity were synthesized by RAFT polymerization using a novel bipyridine-functionalized dithioester as a RAFT agent, and were further complexed with ruthenium ion to produce ruthenium-centered thermosensitive polymers with well-defined structure. Results from UV–vis, fluorescence and DSC characterizations of the thermosensitive polymeric ruthenium complexes indicated that tris(2,2′-bipyridine)ruthenium(II) ion was successfully grafted onto the center of polymer chains.
A novel bipyridine-functionalized dithioester, 5,5‘-bis(thiobenzoylthiomethyl)-2,2‘-bipyridine (3), was first synthesized through a simple ester exchange reaction with the commercially available dithioester, carboxymethyl dithiobenzoate (CMDB), and further used as a RAFT agent in bulk polymerization of styrene for the synthesis of well-defined bipyridine-centered polystyrene polymers. The molecular weight is well-controlled, and also the molecular weight distribution remains quite narrow. This shows that the novel bipyridine-functionalized dithioester 3 is an efficient RAFT agent. More importantly, the good agreement between theoretical and 1H NMR-determined molecular weights indirectly indicates that almost all of the polymer chains are centered by the bipyridine functional groups derived from the new RAFT agent. Two of the bipyridine-centered polystyrene polymers were further complexed with ruthenium(II) ions to produce tris(bipyridine)ruthenium(II)-centered polystyrene metallopolymers. The metallopolymers were characterized by UV−vis, fluorescence, size exclusion chromatography (SEC), and differential scanning calorimetry (DSC) techniques. The characterization data show that tris(bipypridine)ruthenium(II) ions have been successfully incorporated into the center of polymer chains.
We report the synthesis and uses of a novel terpyridine-functionalized chain transfer agent (CTA) that produces well-controlled macromolecular architectures with terpyridine functionalities at one chain end via reversible addition−fragmentation chain transfer (RAFT) polymerization. The terpyridine-terminated macromolecules with well-defined structures were further used for preparation of supramolecular diblock metallomacromolecules by bis(2,2‘:6‘,2‘ ‘-terpyridine)ruthenium(II) complex connectivity. The successful connectivity between two macromolecular blocks via the metallocomplex was confirmed by UV−vis, size exclusion chromatography (SEC), and differential scanning calorimetry (DSC) as well as atomic force microscopy (AFM) techniques.
A new bipyridine-functionalized dithioester was synthesized and further used as a RAFT agent in RAFT polymerization of styrene and N-isopropylacrylamide. Kinetics analysis indicates that it is an efficient chain transfer agent for RAFT polymerization of the two monomers which produce polystyrene and poly(N-isopropylacrylamide) polymers with predetermined molecular weights and low polydispersities in addition to the end functionality of bipyridine. The bipyridine end-functionalized polymers were further used as macroligands for the preparation of star-shaped metallopolymers. Hydrophobic polystyrene macroligand combined with hydrophiphilic poly(N-isopropylacrylamide) was complexed with ruthenium ions to produce amphiphilic ruthenium-cored star-shaped metallopolymers. The structures of these synthesized metallopolymers were further elucidated by UV–vis, fluorescence, size exclusion chromatography (SEC), and differential scanning calorimetry (DSC) as well as NMR techniques. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4225–4239, 2007
Al-SBA-15 mesoporous catalyst with strong Brönsted acid sites and Al stabilized in a totally tetrahedral coordination was
synthesized from the addition of hydrothermally aged zeolite Y precursor to SBA-15 synthesis mixture under mildly acidic condition
of pH 5.5. The materials possessed surface areas between 690 and 850m2/g, pore sizes ranging from 5.6 to 7.5nm and pore volumes up to 1.03cm3, which were comparable to parent SBA-15 synthesized under similar conditions. As much as 2wt.% Al was present␣in the most
aluminated sample that was investigated, and the Al remained stable in totally tetrahedral coordination, even after calcination
at 550°C. Calcined Al-SBA-15 showed high hydrothermal stability when treated with steam (20%v/v in nitrogen) at 650°C for
2h. Textural characteristics are maintained on steam treatment, and very little or no conversion of Al from tetrahedral to
octahedral coordination resulted. The Al-SBA-15 mesoporous catalyst showed significant catalytic activity for cumene dealkylation,
and activity increased as the amount of zeolite precursor added to the SBA-15 mixture was increased. The catalyst’s activity
was not affected by the aging time of the precursor for up to the 24h aging time investigated. This method of introducing
Al and maintaining it in a total tetrahedral coordination is very effective, in comparison to other direct and post synthesis
alumination methods reported.
The thermosensitive [60]fullerene end-capped poly(N-isopropylacrylamide) was successfully synthesized by the reaction of C(60) with dithiobenzoate-terminated poly(N-isopropylacrylamide), which was prepared by reversible addition-fragmentation chain-transfer (RAFT) polymerization in the presence of azobisisobutyronitrile (AIBN). Its structure was determined by FTIR, UV/Vis, and carbon and proton NMR spectroscopy as well as by size exclusion chromatography (SEC). The novel fullerenated polymer retained the thermosensitivity of poly(N-isopropylacrylamide). Moreover, it is soluble in water and most of the common organic solvents. Interestingly, it was able to form nanoparticle clusters in methanol and exhibited significant radical scavenging ability in cell viability and metabolic activity tests with fibroblasts and NOR-3 radicals.
Galvanic Corrosion Fatigue Testing of 7075-T6 Aluminum Bonded with Graphite Epoxy Composite
- S R Brown
- J J Deluccia
Brown, S. R.; Deluccia, J.J., Galvanic Corrosion Fatigue Testing of 7075-T6 Aluminum Bonded with Graphite Epoxy Composite , Navel Development Center Report, NADC- 77328-60, Jan. 1978