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The band gaps of three forms of polyaniline (PANI) are calculated using the DFT method with the B3LYP functional and SV(P) basis set. This marks the first time that the band gap for this polymer has been calculated using this DFT method. The calculations include an investigation of the effect of varying the benzoid–quinoid structural units, the effect of increasing oligomer length, and the inclusion of Michael’s addition structures, which could be residual in the polymer depending on the chosen synthetic method. All results were compared with the experimentally determined band gap of 1.5 eV as typically reported in the literature. A commonly used structural motif of alternating benzoid–quinoid units and a ratio of 0.5:0.5 benzoid–quinoid resulted in a computed band gap of 1.9 eV. Inclusion of one extra quinoid unit gave rise to a band gap of 1.3 eV. Incorporation of a Michael’s addition structure was found to dominate the band gap calculation, yielding a localized LUMO and a band gap of 1.3 eV that was insensitive to the polymer chain length and composition.

Microfibers (mf) are the most common type of microplastic in the environment. Few studies have focused on their abundance in atmospheric deposition in background environments. In the current study, we collected wet-only and bulk rainfall from four precipitation chemistry monitoring stations, primarily located in coastal areas around Ireland. Anthropogenic mf were observed in all samples; the average deposition across the four study sites was 80 mf m-2 day-1. Wet-only mf deposition was 70 mf m-2 day-1 compared with bulk deposition of 100 mf m-2 day-1. The wet-only collectors were estimated to capture ∼70% of the bulk collectors, suggesting that dry deposition makes up at least 30% of total deposition. Meteorological variables, i.e., relative humidity, rainfall volume, wind speed, and wind direction, were significantly related to mf abundance, suggesting that rainfall washout and air mass movement are important predictors of mf deposition in background regions. In total, 15% of all anthropogenic mf were identified as plastic. The most abundant polymer type was polyester or polyethylene terephthalate at 71%, followed by polyacrylonitrile at 11%, polyethylene at 11%, and polypropylene at 4%. The average deposition of plastic mf was 12 mf m-2 day-1.

Green chemistry metrics and life-cycle analysis (LCA) were used to assess inefficiencies in two current organic chemistry experiments conducted in third-year organic chemistry to synthesize (E)-stilbene from benzaldehyde. An alternative Wittig-based, greener, one-pot experiment using the same starting material was selected as a vehicle to introduce the concepts of green chemistry to students. The original learning objectives for the experiment were maintained with additional learning objectives in green chemistry introduced. The theoretical and experimental calculations of all experiments were compared using the standard univariate and multivariate metrics for LCA analysis, to assess the impact of chemical waste generated on the environment. The LCA metrics showed that the Wittig-based experiment addressed eight principles of green chemistry and possessed fewer environmental hazards, produced less waste (E-factor), and had better isomeric purity, mass, and process efficiency including factors such as global warming potential than the current lab methods. Results from a survey of students who conducted all three experiments indicated an enhanced knowledge of green chemistry and an improved sense of chemical and environmental impact. The research provided a platform to introduce sustainable chemistry practices to organic chemistry students at the undergraduate level.

A UV-crosslinkable two-component organically modified silicate (ORMOSIL) sol–gel coating was made using 3-methacryloxypropyltrimethoxysilane (MaPTMS) and tetraethoxysilane (TEOS) in two stages. In the first stage, key synthetic parameters, such as use of co-solvents, reaction temperature, reaction time, and catalyst, were optimized for the rapid hydrolysis and condensation of the ORMOSIL. The ORMOSIL material was made using isopropanol as the solvent and HNO3 as the acid catalyst. This resulted in a sol–gel that underwent rapid hydrolysis in 35 s. The ORMOSIL demonstrated extensive condensation after 10 min of stirring at room temperature followed by 10 min of heating at 60°C as monitored by 29Si-NMR. In the second stage, the ORMOSIL was successfully crosslinked with up to 70% consumption of the acryl functionality within 5 min under UV light exposure in the presence of photoinitiator. The UV-crosslinked coating exhibited high adhesion to low-carbon steel and impeded substrate corrosion from 17 to 25 h under an accelerated corrosive environment. Schematic representation of the hydrolysis and condensation of 3-methacryloxypropyltrimethoxysilane (MaPTMS) and tetraethoxysilane (TEOS) system and the 2D gHMBC 29Si NMR of the system.

Peroxidase-based reagents that react with whole blood typically undergo internal quality control tests for reactivity prior to their use at a crime scene. This study presents a synthetic polymer alternative to using whole mammalian blood as a luminol reagent control testing material. The luminol-reactive polymer was developed by integrating horseradish peroxidase into a silicon-based sol-gel matrix. Liquid formulations of the polymer were made to simulate forensically relevant luminol reactivity with dried, whole ovine blood at dilutions up to 1:1 × 106. Photoemission from chemiluminescence reactions were characterized as a function of time using a SpectraMax® M3 microplate reader luminometer over a duration of three minutes. The maximum chemiluminescence intensity, time at maxima, reaction half-life, and overall behaviour of the sol-gels and two commercially available materials are reported. The behaviour of each material was statistically compared to the whole blood standards using a two-dimensional Kolmogorov-Smirnov test, which suggests that the sol-gels have a more realistic and statistically similar reactivity to neat (p = 0.835) and diluted (1:1 × 106) blood (p = 0.998) than the commercially available materials (p

We have demonstrated that our patented, crosslinked, sol–gel, epoxy–thiol silicates made from the combination of (a) tetraethoxysilane (TEOS, T), 3-glycidoxypropyltrimethoxysilane (GPTMS, G), and the (b) sulfur-containing 3-mercaptopropyltrimethoxysilane (MPTMS, S) with TEOS in a 1:1 stoichiometric ratio form the 1:1 TGST (crosslinked epoxy and thiol silicates) coating, which can be successfully utilized for the corrosion protection of low-carbon steel. Alcohols that are a by-product of sol–gel reactions influence the network formation, crosslinking density, and formulation stability, are volatile organic contents, and are regulated in the coatings industry. To improve environmental sustainability, a series of low-alcohol (LA) formulations with TG:ST ratios of 3:1 to 1:3 was prepared to investigate the microstructural development and crosslinking reactions emerging from the interplay of the hydrophobic thiol and polar epoxy silicates induced by the low-alcohol environment. The impact on crosslinking density was characterized by Fourier Transform Infrared (FTIR), Raman, XPS, viscosity, and pot-life measurements. Low-alcohol TGST (LA(TGST)) formulations were compared, using the example of 1:1 TGST, to corresponding TGST formulations where alcohols were retained. The reduced impact of LA(TGST) formulations on global warming was quantified. The glossy and scratch-resistant LA(TGST) coatings showed 71% enhanced corrosion protection compared to the non-crosslinked hybrids.

In this work, a comparative study between three carbon materials has been carried out to investigate the impact of the micro/mesoporous structure of the carbon substrate on their adsorption capabilities. The study included two commercial carbons: Darco KB-G (AC), and Vulcan XC-72R (VC). The third carbon material was a mesoporous material (MC), with tailored micro/mesoporous structure and surface area obtained by carbonization of a resorcinol?formaldehyde (RF) polymer gel using both soft and hard template materials. Melamine was used as a model adsorbate in both acid and alkaline solutions. For all carbons, melamine adsorption was found to be pH dependent with higher adsorption from alkaline solutions than from acidic solutions. To the best of our knowledge, these are the first reported values for the adsorption of melamine to these carbon materials. Adsorption data obtained using the Langmuir model were compared with theoretical studies involving melamine as a building block in the self-assembly of molecular structures on carbon substrates, and analyzed using the results of several characterization studies carried out as part of this research work, some of which include nitrogen and CO2 adsorption isotherms, Raman spectroscopy, powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). Fil: Hynes, Lucas. University of Ontario Institute of Technology; Canadá Fil: Montiel, Gonzalo. Instituto Nacional de Tecnología Industrial; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes; Argentina Fil: Jones, Allison. University Of Ontario Institute Of Technology; Canadá Fil: Riel, Donna. University Of Ontario Institute Of Technology; Canadá Fil: Abdulaziz, Muna. University Of Ontario Institute Of Technology; Canadá Fil: Viva, Federico Andrés. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Oficina de Coordinacion Administrativa Ciudad Universitaria. Unidad Ejecutora Instituto de Nanociencia y Nanotecnologia. Unidad Ejecutora Instituto de Nanociencia y Nanotecnologia - Nodo Constituyentes | Comision Nacional de Energia Atomica. Unidad Ejecutora Instituto de Nanociencia y Nanotecnologia. Unidad Ejecutora Instituto de Nanociencia y Nanotecnologia - Nodo Constituyentes.; Argentina. Comisión Nacional de Energía Atómica. Gerencia de Área Investigaciones y Aplicaciones No Nucleares. Gerencia Física (CAC). Departamento de Física de la Materia Condensada; Argentina Fil: Bonetta, Dario. University Of Ontario Institute Of Technology; Canadá Fil: Vreugdenhil, Andrew. Trent University; Canadá Fil: Trevani, Liliana. University Of Ontario Institute Of Technology; Canadá

Organic–inorganic hybrid coatings of crosslinked epoxy and thiol silicates (TGST) were synthesized for the corrosion protection of low carbon steel via a waterborne sol-gel route. The coatings were synthesized in two stages; in the first step two separate aqueous formulations of epoxy and thiol decorated silica colloids were prepared and subsequently crosslinked in a 1:1 ratio in the second stage. The structure and rate of crosslinking was monitored using Raman spectroscopy. Formulation stability was measured based on viscosity changes and pot-life assessment. The novel material was characterized for its particle size using dynamic light scattering. Viscosity average molecular weight was calculated using Fikentscher’s equation and using polyethylene oxide molecular weights as a calibration standard. The covalently bonded epoxy-thiol silicate thin-film coating was uniform and defect free. Accelerated corrosion resistance was tested by exposing the panels to standard salt solution tests. TGST showed a 96% improvement in corrosion inhibition over the non-crosslinked formulations in a corrosive environment. The synthesis and characterization of TGST using a simple approach, revealed key synthetic parameters for generating optimized sol-gel corrosion prevention materials.

This work investigates the spreading dynamics of three candidate sol-gel solutions, of ranging viscosities, surface tensions and densities, and compares them with water and two commercial blood substitute products. Droplets were created with different sizes (10 to75μL) and impact velocities (1.4 to 6.0m/s) to strike 176gsm cardstock. Over 2200 droplets were created using the six different fluids and their final dried stain diameter was measured. Droplet spread was plotted using the Scheller and Bousfield correlation and uses effective viscosity as a parameter for non-Newtonian fluids. Comparing the results to an expected whole human blood range validated the spread of the candidate FBS sol-gel material in passive drip bloodstain pattern simulation. These findings complement the practical application of the material as a safe substitute for demonstrating droplet spread under controlled conditions on hard paper surfaces.

This work explores the crown formation dynamics of blunt force impact onto a thin film of sheep's blood. Three weapons – a hammer head, a simulant baseball bat, and a metal bar – were used to impact blood on fibreboard, cloth, and sponge. Impact velocity was controlled using a custom impact device. High-speed videos were collected and analyzed with motion tracking and computing software. Interestingly, crowns were not observed to form in seven out of nine trials where each weapon struck the bloodied sponge. The widths and heights where observable crowns formed were measured and ranged between 0 to 105 mm and –0.4 to 36 mm, respectively. Bloodied material type was observed to influence the size and shape of the crown; however, the weapon heads used in this study did not. Three unusual cases of rim instability were observed where droplets were sent in the opposite direction of the expanding crown. This work supports the idea that the formation dynamics of mechanisms caused by blunt force impact are ...

Solution-gelation chemistry has promising applications in forensic synthetic blood substitute development. This research offers a silicon-based sol-gel approach to creating stable materials that share similar rheological properties to that of whole human blood samples. Room temperature, high water content, silicon sol-gels were created using the organosilane precursors 3-glycidoxypropyltrimethoxysilane and tetraethylorthosilicate along with various concentrations of filler and pigment. Shear-thinning non-Newtonian properties were observed within most formulations of the presented materials. The effects of colloidal concentration, temperature, age and filler addition on the viscosity of the sol-gels were investigated. SEM-EDS analysis was used to identify the behavior of the fillers within the film and support their inclusion for basic bloodstain pattern simulation. A final proposed candidate sol-gel was assessed using a previously reported passive drip simulation test on a hard, dry surface and passed. This works represents encouraging development in providing safe material alternatives to using whole human blood for forensic training and research.

There are numerous benefits to answer-until-correct (AUC) approaches to multiple-choice testing, not the least of which is the straightforward allotment of partial credit. However, the benefits of granting partial credit can be tempered by the inevitable increase in test scores and by fears that such increases are further contaminated by a large random guessing component. We have measured the effects of using the immediate feedback assessment technique (IF-AT), a commercially available AUC response system, on the scores of a typical first-year chemistry multiple-choice test. We find that with a particular commonly used scoring scheme the test scores from IF-AT deployment are 6–7 percentage points higher than from Scantron deployment. This amount is less than that suggested by previous studies, where the mark increase was calculated in a purely post hoc manner and thus neglected affective changes of students’ behavior associated with the IF-AT technique. Furthermore, we have strong evidence that partial cr...

This research uses high-speed video analysis of bloodstain impact events to investigate the influence of impact velocity, fluid depth and free-space on the characteristics of the mechanism. We focus on the changes in the crown growth over time. This work demonstrates qualitative differences in the impact mechanism under a range of impact conditions. These differences are further explained quantitatively as a function of measured crown width and height lengths over time. Fluid dynamic explanations of this growth are featured in the results and discussion. A comparison to water dynamics is reported. Our image analysis demonstrates that droplets are consistently formed at points which are different from the impactor/fluid interface and that this difference is fluid dependent. This fluid dependency demonstrates the importance of accurately modeling fluid dynamics of blood when designing and deploying blood substitutes in forensics applications.

Impact patterns that are generated on dark surfaces can become camouflaged creating difficulties with conventional photographic methods that are used when estimating the area of origin. Chemical enhancement is an alternative technique that can be used to visualize these latent bloodstains. The application of Acid Yellow 7 to already fixed bloodstains provides a robust enhancement protocol which yields minimal stain distortion. Image J software was utilized to count stains, resulting in an approximate 5% increase in small stain detection post-enhancement. Area analyses also performed with Image J demonstrates that the average area of a single stain increases by a factor of approximately 1.24 post-enhancement. When using the BackTrack™ suite of programs this enlargement does not significantly affect the calculated impact angle of an enhanced bloodstain when compared to that of its original deposition (P= 0.585). As a result, the area of origin can be estimated within the accepted error of ± 7 cm fro...

Ceramic carbon electrodes were prepared via polymerization of silane materials containing sulfonic acid groups in the presence of Pt/Vulcan XC72. Cyclic voltammetry and electrochemical impedance spectroscopy were used to investigate the effects of sulfonic acid functionalities on platinum utilization and proton conductivity, as well as CCE microstructure. It has been determined that incorporation of small amounts of sulfonated silane to the CCE structure can lead to a profound enhancement of proton conductivity despite decreases in BET surface area. Retention of surface area was achieved through combination of sulfonated and unsulfonated organosilane precursors. These composite samples show improved performance during fuel cell testing than for CCEs prepared using unsulfonated precursors.

The three isomers of phenylenediamine have been used as crosslinking agents for epoxide decorated silica colloids generated by high water content sol–gel chemistry techniques. The resulting materials were used as corrosion protection thin films for aluminum alloys in corrosive environments. These hybrid epoxy-amine crosslinked sol–gel materials have demonstrated an order of magnitude improvement over similar materials crosslinked with aliphatic diamines along with novel electrochemical and coloration behavior. The processes behind these performance improvements are explored and two possibly complementary mechanisms are identified, namely exposure-triggered toughening of the materials through oxidative polymerization of the phenylenediamines and an increase in corrosion inhibition via the formation of electroactive phenylenediamine oligomers.

Gold nanoparticles were encapsulated in sol–gel matrices with different amine cross-linker molecules in order to determine the cross-linker influence on nanoparticle agglomeration behaviour during encapsulation. The role of a stabilizing surfactant (SDS) was also investigated. The NP aggregate sizes were tracked using the UV surface plasmon resonance band (SPR), which red-shifts with increased particle size. It was found that use of long carbon chain cross-linkers such as 1,4-diaminobutane resulted in large Au NP aggregates, compared to short-chain analogs such as 1,2-diaminoethane, with which almost no agglomeration was observed. The SPR splitting pattern observed in samples with nanoparticle agglomeration is consistent with formation of nanodimensional objects with major and minor axes similar to nanowires during encapsulation within the cross-linked sol–gel material. The cross-linkers diethylenetriamine and triethylenetetraamine containing both terminal and internal amines demonstrated nanoparticle stabilization beyond that observed for similar sized diamine cross-linkers. This is ascribed to the multiple cross-linking sites available on these polyamines and the resulting reduction in matrix void volume.

A sol–gel derived hybrid material with nanometer dimensional layers is described. The material was fabricated using alternating layers of preformed silica colloids decorated with either epoxide or amine functional groups as a means of providing horizontal ordering to an otherwise amorphous material. The layer thicknesses, as determined by XPS escape depth calculations, are 20 nm for the epoxide and 7 nm for the amine decorated material. The sharpness of the interfaces, the homogeneity of the surfaces and the chemical availability of the functional groups following deposition are demonstrated by X-ray photoelectron spectroscopy, grazing angle infrared spectroscopy and aqueous contact angle measurements. The functional groups of the uppermost layer were readily modified by diethylamine or propylene oxide in tetrahydrofuran at 100 °C.

The search for chromate replacements in corrosion prevention materials has identified the use of hybrid sol–gel coatings as one, very promising approach. Appropriately functionalized hybrid sol–gel materials can be crosslinked to enhance their chemical durability and mechanical strength. In this work, we evaluate three crosslinkers used in a tetramethoxysilane–glycidoxypropyltrimethoxysilane binary sol–gel system in order to identify the role of the crosslinkers in corrosion protection. The crosslinkers examined were ethylenediamine, N-aminethylepiperazine, and diethylenetriamine. The sol–gel coatings were examined by contact angle, atomic force microscopy, and electrochemical impedance spectroscopy (EIS). Circuit modeling of the EIS results yielded valuable insights into the significant differences between the durabilities of the variously crosslinked coatings. Crosslinker hydrophobicity was identified as not playing a significant role whereas the number of reactive sites per crosslinker and the resulting morphology of the material may be an important parameter.

Aqueous phase metal nanoparticles were formed by laser ablation and subsequently encapsulated in sol–gel derived alkyl-siloxane solids. The resulting nanoparticles were encapsulated into a mixture of hydrolyzed tetramethoxysilane and 3-glycidoxypropyltrimethoxysilane by addition of nanoparticle-containing solutions. Silanol condensation and epoxy-amine crosslinking was used to solidify the matrix. The production of gold nanoparticles and their fate upon encapsulation were characterized by the evolution of the surface plasmon absorbance band and by transmission electron microscopy (TEM). Encapsulation resulted in an increase in particle size and size distribution as well as a significant red shift in the surface plasmon absorbance band from 520 nm to 545 nm at low nanoparticle concentrations and 565 at high nanoparticle concentrations. This is attributed to chemical interactions with methanol and enhanced nanoparticle–nanoparticle interactions.

Advanced materials capable of responding to their chemical environment have been synthesized from the highly tailorable combination of sol–gel chemistry and epoxy-amine cross-linking reactions. Several materials were prepared from tetramethoxysilane (TMOS), and 3-glycidoxypropyltrimethoxysilane (GPTMS), and polyamine cross-linking agents. These cross-linking agents included diethylenetriamine (DETA), N-(2-aminoethyl)-piperazine (AEPZ), 1-(2-aminoethyl)-piperidine (AEPD), and ethylenediamine (EDA). Selective release of the indicator 4-methylaminoazobezene-4′-sufonic acid from these materials was monitored using UV–visible spectroscopy. Studies of the release demonstrate that it is continuously pH responsive with the greatest release at extreme pHs. Release is triggered by changes in the electrostatic interactions between the molecular additive and the matrix. These interactions can be readily tuned by altering the cross-linking agent.

Two coatings capable of responding to their chemical environment have been synthesized using a combination of sol–gel techniques and epoxy-amine cross-linking reactions. These triggered release materials were prepared from tetramethoxysilane (TMOS), 3-glycidoxypropyltrimethoxysilane (GPTMS), methyltrimethoxysilane (MTMOS) and cross-linked with diethylenetriamine (DETA). Studies of the release of a molecular additive were performed in solutions ranging in pH from 2.5 to 11.0, over a 90-min period. The coating response is shown to be pH dependent with the greatest release occurring at the extreme pHs. Zeta potential measurements of the 1:3 coating were used to approximate the isoelectric point of the coating. Extreme–moderate pH cycling experiments were performed to determine the effect of matrix decomposition on the release of molecular additive from each of the coatings. These experiments indicate that electrostatic interactions and not coating decomposition is the major component of the release mechanism.

A mechanical device that uses gravitational and spring compression forces to create spatter patterns of known impact velocities is presented and discussed. The custom-made device uses either two or four springs (k1 = 267.8 N/m, k2 = 535.5 N/m) in parallel to create seventeen reproducible impact velocities between 2.1 and 4.0 m/s. The impactor is held at several known spring extensions using an electromagnet. Trigger inputs to the high-speed video camera allow the user to control the magnet's release while capturing video footage simultaneously. A polycarbonate base is used to allow for simultaneous monitoring of the side and bottom views of the impact event. Twenty-four patterns were created across the impact velocity range and analyzed using HemoSpat. Area of origin estimations fell within an acceptable range (ΔXav = -5.5 ± 1.9 cm, ΔYav = -2.6 ± 2.8 cm, ΔZav = +5.5 ± 3.8 cm), supporting distribution analysis for the use in research or bloodstain pattern training. This work provides a framework for those interested in developing a robust impact device.

Nanoscale dispersion of only a few weight percentage of layered silicate (montmorillonite) in nylon 6 and epoxy results in the formation of a uniform passivating and self-healing inorganic surface region upon exposure to oxygen plasma. The enrichment of inorganic is compositionally graded with respect to the surface and is due to the preferential oxidation of the polymer from the nanocomposite and the corresponding enhancement of the nanoscale layered silicate on the surface. The structure of the inorganic region is turbostratic, with an average distance between layered silicates of 1−4 nm. This ceramic-like silicate layer provides an overcoat to the nanocomposite and can significantly retard the penetration of oxygen plasma. Thus, layered silicate containing nanocomposites may enhance the survivability of polymeric materials in aggressive oxidative environments, such as atomic oxygen in low earth orbit (LEO). The formed inorganic region was characterized chemically and morphologically by X-ray photoelect...

Precise analysis is essential to the development of novel coating technologies and to the systematic modification of metal surfaces. Ideally, these analysis techniques will provide molecular information and will be sensitive to changes in the chemical environment of interfacial species. Many of the techniques available in the field of vibrational spectroscopy demonstrate some of these characteristics. Examples of the ways in which FT-IR spectroscopy are applied to the investigation of coatings at AFRL will be described. Attenuated total reflectance (ATR), specular reflectance and photoacoustic spectroscopy (PAS) are important techniques for the analysis of surfaces. Both ATR and PAS can be used to provide depth-profiling information crucial for the study of coatings. Recent developments in digital signal processing (DSP) and step scan interferometry which have dramatically improved the reliability and ease of use of PAS for depth analysis will be discussed.

Current coatings for aircraft corrosion protection are based on chromate surface treatments, primers, and topcoats. One approach to developing a chromate-free surface treatment is through the use of sol-gel materials that interact strongly with both the substrate and the subsequent polymer layers. Results are reported here on a new sol-gel technique using a pre-formed, self-assembled, nano-phase particle (SNAP) sol-gel system. SNAP films have been investigated by infrared spectroscopy, atomic force microscopy, and electrochemical methods. Potentiodynamic polarization and electrochemical impedance spectroscopy demonstrated that the SNAP system generates high quality, defect-free, durable films. Formulation parameters, including crosslink density and coupling agent application, were optimized based on experimental results.

Cesium oxythiomolybdate (Cs2MoOS3) is a potential high temperature solid lubricant. It undergoes complex oxidation reactions at elevated temperatures, but continues to provide lubrication above the oxidation temperature. Therefore, in order to determine the nature of the lubricant at elevated temperature, it is necessary to understand the thermal chemistry of Cs2MoOS3in an air environment. The thermo-oxidative stability of Cs2MoOS3was evaluated between room temperature and 800°C in air. Melting and phase transition temperatures were determined. X-ray photoelectron spectroscopy, micro-Raman scattering and x-ray diffraction were used to identify the chemical species evolved at increasing temperatures. As-received Cs2MoOS3was not pure. It also contained cesium molybdates, molybdenum oxides, and Cs2SO4. Between 300–400°C, the material began to decompose forming Cs2SO4and MoS2. Between 400–600°C, Cs2MoOS3also formed cesium molybdates and molybdenum oxides. In addition, the Cs2SO4began to oxidize to cesium oxides (which melted) and SOxgas. Also, MoS2oxidized to MoO3. At approximately 700°C, MoO3began to sublime. Upon cooling from 800°C, the material was primarily cesium oxides and Cs2MoO4, with small amounts of complex cesium molybdates and molybdenum oxides.

The ligand diethylenetriamine (DETA) has been successfully coupled to carboxy-terminated magnetic particles, using the carbodiimide EDCI. Amine related peaks from DETA are seen in infrared measurements. The reaction with DETA involves a rearrangement of the self-assembled molecules of dibenzoic acid diamide bolaamphiphile, DBSC-10, on the maghemite, as seen from a shift of methylene peaks, indicating less mobile hydrocarbon chains. XPS measurements and a deconvolution of peaks indicate that one out of two molecules of DBSC-10 is reacting with DETA to form new amide linkages. This gave an amount of DETA-reacted DBSC-10 molecules on the surface of 84 μmol g−1 of carboxy-terminated particles. Titration of the DETA-reacted particles show the titration of two different types of protons, amine and carboxylic, in the ratio of 1:1. Finally, the amount of base required for the complete titration of DETA-reacted particles (0.5 ml per 25 mg of titrated particles) excludes the possible cross-linking reaction of DETA with free carboxylic groups from DBSC-10.

It has been shown that diethylenetriamine (DETA)-functionalized magnetic carriers are able to complex copper ions from dilute streams. Complexometric titration using a copper selective electrode indicates the complexation of 0.52 μmol of Cu2+ per 50 mg of magnetic carriers. This loading capacity is equivalent to the removal of 100 ppm of copper ions from a 1-liter solution by 3 g of magnetic carriers. X-ray photoelectron spectroscopy (XPS) results confirm the presence of Cu2p bands, indicating the loading of copper ions. A shift of the nitrogen N1s bands to higher binding energies confirms the involvement of secondary amine and amide nitrogen atoms from DETA-functionalized carriers in copper complexation.

Direct surface analysis by infrared spectroscopy is a useful technique for detection of xanthate species on sulphide minerals. However, infrared detection limits require xanthate dosages that are often one or two orders of magnitude higher than are used in practice. This paper presents an alternative approach to the analysis of collectors on mineral surfaces. A novel gas-phase infrared technique (HAGIS) has been applied to the indirect analysis of ethylxanthate on lead, zinc and copper sulphide mineral surfaces and also on flotation products from copperzinc and leadzinc ores at xanthate concentrations which are comparable to those used in the mineral processing industry. HAGIS relies on the detection of the gas-phase species generated by the thermal decomposition of xanthates adsorbed on mineral surfaces. In this study, the primary decomposition products generated under an air atmosphere include carbonyl sulphide (COS), carbon dioxide (CO 2 ), carbon disulphide (CS 2 ) and ethanol. The amounts of these species were compared with product distributions observed for the decomposition of known ethylxanthate complexes. Correlations between the decomposition species provide evidence for the speciation of the collector in the flotation product. The decomposition species can be readily detected from xanthate dosages that are much lower than are the detection limits of traditional, direct surface analysis techniques.

Na-aluminosilicate glasses with Na/Al > 1 and added Ti or Zr have been analyzed by Raman spectroscopy to determine the effect of Cl on glass structure. Spectra of Ti-bearing glasses show a significant difference between the Cl-free and the Cl-bearing composition. The Cl-free glass spectrum contains a strong, asymmetric peak at 900 cm−1 which is associated with Ti in fivefold coordination. This peak is shifted to higher frequency and becomes more symmetric with the addition of 0.3 wt% Cl. Deconvolution of the high-frequency waveband indicates differences between spectra are the result of a contribution from a peak at 945 cm−1 resulting from Ti–O vibrations in fully polymerized titanate tetrahedra. It is proposed that addition of Cl destabilizes [5]Ti in favor of tetrahedral coordination as a result of competition between Cl and titanate groups for alkalis. The spectra of Zr-bearing glasses show a strong peak at 980 cm−1 which is not seen in spectra of the base glass, indicating a vibrational mode associated with a zirconosilicate structure. There is no discernible difference between the Raman spectra of Zr-bearing glasses with and without added Cl, indicating that the local structure around Zr is insensitive to the presence of Cl.

Resonance Raman spectra with Q-band excitation are reported for microperoxidase-11, the cytochrome c analog. Spectra were acquired in the mid-frequency range for the oxidized, and reduced forms of the undecapeptide, as well as for the imidazole and carbonyl complexes. Oxidation and spin state marker bands of the undecapeptides are consistent with a six-coordinate, low spin iron in both oxidation states. Porphyrin core size correlations yield a porphyrin-centre to pyrrole-nitrogen distance of 2.00 A for MP11, suggestive of a six-coordinate species in a distorted heme environment. Molecular dynamics results show that the non-planarity of the heme of the parent cytochrome is conserved in the microperoxidase and its carbonmonoxy analog.

Diffuse reflectance infrared Fourier-transform spectroscopy (DRIFTS) and headspace analysis gas-phase infrared spectroscopy (HAGIS) were used to investigate interactions between soils and the gasoline additive methylcyclopentadienylmanganese tricarbonyl (MMT). Various soil samples, as well as alumina and silica substrates, were studied. Each substrate exhibited a splitting or broadening of the degenerate e v(CO) band of MMT, suggesting an interaction involving one or two of the CO ligands. The adsorption was shown to be reversible under relatively mild conditions using HAGIS. The proposed interaction is of the Bronsted type, involving the carbonyl oxygen and a surface-bound water or hydroxyl group. This type of interaction could stabilize MMT by inhibiting photo-ejection of CO ligands, a common first step in the decomposition of organometallic carbonyl compounds such as MMT.

Head-space analysis by gas-phase infrared spectroscopy (HAGIS) allows the facile examination of the decomposition mechanisms of the metal xanthates [metal-( O -alkyldithiocarbonates], Fe(EtOCS 2 ) 3 , Zn(EtOCS 2 ) 2 , Cu(EtOCS 2 ), Pb(EtOCS 2 ) 2 and Ni(EtOCS 2 ) 2 , over the temperature range 25–120°C. These metal xanthates fall into two groups based on the generation of the primary gaseous decomposition products, CS 2 , COS and CO 2 . The first group, consisting of Fe(III) and Zn(II) xanthates, decompose readily, forming mostly CS 2 and COS in a constant ratio and leaving, initially, a metal-alkoxide residue. In the second group, decomposition is relatively small, generating CO 2 and COS, with the proportion of COS increasing as the temperature increases and CS 2 formation occurring only at the upper end of the temperature range. The residue is more of a metal-thioalkyl species in this case. Presumably, CO 2 is formed by re-insertion of COS into a metal alkoxide and elimination of CO 2 , leaving a thioalkyl moiety. Volatile metal-xanthates are probably observed in the gas-phase, allowing examination of the changes concomitant to the vaporization of the discrete metal xanthates from network or partially associated solids.

The O -ethyldithiocarbonate (ethyl xanthate, CH 3 CH 2 OCS − 2 ) anion is a widely used reagent in mineral processing for the separation of sulphide minerals by froth flotation. Ethyl xanthate interacts with mineral powders to produce a hydrophobic layer on the mineral surface. A novel infrared technique, headspace analysis gas-phase infrared spectroscopy (HAGIS) has been used to study the in situ thermal decomposition products of ethyl xanthate on mineral surfaces. These products include CS 2 , COS, CO 2 , CH 4 , SO 2 , and higher molecular weight alkyl-containing species. Decomposition pathways have been proposed with some information determined from 2 H- and 13 C-isotope labelling experiments.

Soil samples were washed with dilute solutions of the toxic anti-knock fuel additive methylcyclopentadienyl manganese tricarbonyl (MMT) in hexanes and commercial unleaded gasoline. Diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) was then used to detect the v(CO) modes of MMT, and subsequently 13CO-enriched MMT, in the soil samples. The presence of MMT in the soils was further confirmed by mass spectrometry. Concentrations corresponding to ∼10 ppm Mn in soil could be detected by DRIFTS of the dry samples, and, most interestingly, there was no evidence of significant MMT decomposition over a period of eight months. Apparently, MMT is stabilized by physisorption onto the soils. In the absence of such stabilization, however, MMT undergoes photolytic and thermal decomposition in a matter of minutes. These results suggest the possibility of longer-term environmental problems associated with gasoline spills containing MMT than was previously suspected.

A novel passive sampler for mercury monitoring was prepared using organosilica sol–gel materials. It comprises a binding layer with thiol groups for mercury complexation and a porous diffusive layer through which mercury can diffuse and arrive at the binding layer. Our study demonstrated that this new sampler follows the principle of passive sampling. The mass of mercury accumulated in the binding layer depends linearly on the mercury concentration in solution, the sampling rate and the exposure time. A typical sol–gel sampler is characterized by a diffusive layer of 1.2 μm, in which mercury ions diffuse with a coefficient of D = 0.09 × 10 −6 cm 2 s −1 , resulting in an uptake R s of 8.8 mL h −1 . The capacity for mercury uptake is approximately 0.64 μg cm −2 . Mercury diffusion and binding in the passive sampler are independent of the type of mercury-chloride complex, which potentially opens the door to use this device for mercury monitoring in a wide range of natural waters.

The first 1:2 metal complexes of 2-(2'-pyridyl) quinoxaline (L) have been isolated. The physical and spectroscopic characteristics of the compounds [MCl(2)L(2)] (M=Ni, Cu, Cd) and [Cu(1)L(2)](PF6) are described. The structure of the copper(I) complex has been determined by X-ray diffraction methods. Crystals are orthorhombic, space group P-cnb with a=11.014(2), b=12.886(2), c=17.806(4) Angstrom, V=2527.1(9) Angstrom(3) and Z=4. Refinement of the structure gave a final R factor of 0.046 (R(w)=0.041) for 814 unique reflections having I>2.0 sigma(I). The ligand L acts as a bidentate chelate, the ligated atoms being the pyridine nitrogen and the nearest quinoxaline nitrogen. The structure of [CuL(2)](+) consists of a distorted tetrahedral arrangement around the copper(I) atom with Cu-N bond lengths of 2.023(6) and 2.059(5) Angstrom, and the N-Cu-N angle of the chelating ligand equal to 80.6(2)degrees. A monomeric trans pseudo-octahedral stereochemistry is assigned for the [MCl(2)L(2)] complexes. Inorganica Chimica Acta

A series of polyurea and polyurethane ceramer coatings were formulated using hexamethylene diisocyanate (HDI) isocyanurate, alkoxysilane-functionalized HDI isocyanurate, tetraethyl orthosilicate (TEOS) oligomers and cycloaliphatic polyesters. The coatings were prepared as a function of alkoxysilane-functionalized HDI isocyanurate and TEOS oligomers concentration. Also, the effect of acid catalyst was investigated. The corrosion resistance of polyurea or polyurethane ceramer coating systems were evaluated using a prohesion chamber on aluminium alloy 2024-T3 substrate. The polyurethane ceramer coatings were compared with the chromate pretreatment and the epoxy-polyamide primer containing the chromate pigment. In addition to prohesion, the interface between the coating and substrate was characterized using X-ray photoelectron spectroscopy (XPS). The prohesion data showed that the corrosion was inhibited by the TEOS oligomers. However, high concentrations of TEOS oligomers and acid catalyst produced blistering in the polyurea/polysiloxane ceramer coatings. The prohesion data alsoi showed that the corrosion protection of ceramer coatings performed as well as the chromate pretreatment and competitively with the epoxy primer. From the XPS and prohesion data, a self assembling silicon oxide layer at the metal-coating interface was proposed.

Biosilicate hybrid materials represent a tremendously broad range of materials from inorganic matrices hosting small proteins (Gill und Ballesteros, J Am Chem Soc 120:8587–8598, 1998) to chitosan scaffolds with small silicate inclusions. (Silva et al., J Mater Chem 15:3952–3961, 2005) In this chapter, we will focus on the chemical interactions within a biosilicate hybrid and the effect that these interactions have on the thermal properties of the material. Broadly, we can consider biosilicate hybrids to be a material made up of both an inorganic and a bioorganic polymeric network with varying degrees of chemical interaction. These binary network materials are an interesting area of research as the nature of the two dissimilar networks can be used to temper the properties of the resulting hybrid not only by their content and their particular chemical composition but also in their degree of chemical interaction.