Atomic layer deposition (ALD) is a technique by which surface-based reactions between a precursor molecule (often metal-containing) and a co-reactant (e.g. H2O, O2 or H2) yield highly uniform and conformal (ultra-)thin films. The precursor and co-reactant are each delivered in the gas phase, separated from one another by inert gas purge steps. The self-limiting nature of these surface-based reactions allows the thickness of the film to be controlled solely by the number of ‘precursor – purge – co-reactant – purge’ cycles. This nano-scale control of film thickness allows for a large number of applications such as in flat panel displays, fuel and solar cells, and microelectronic devices. The first goal of this project was the pursuit of new low-temperature methods for main group elemental ALD using silyl-substituted precursor molecules. The second goal of the project was the development of alternative methods for thin film deposition of group 4 (M = Hf, Zr) oxides that would encourage effective (ie. void-free) filling of narrow (<20 nm) trenches in high-aspect-ratio (HAR) substrates. This thesis includes the development of new precursor molecules and reaction pathways, evaluation of precursor molecular structures, thermal stability, volatility and solution reactivity, identification of appropriate experimental conditions for ALD, and characterization of the resulting thin films. ALD of elemental antimony was achieved on hydrogen-terminated silicon (H-Si) and SiO2/Si substrates using Sb(SiMe3)3 (2-1) and SbCl3 in the temperature range 23- 65 °C. The mirror-like films were confirmed to be composed of crystalline antimony by XPS (for the film deposited at 35 °C) and XRD, with low impurity levels and strong preferential orientation of crystal growth relative to the substrate surface. To the best ofour knowledge, this is the first example of room temperature thermal ALD (with demonstrated self-limiting growth) of a pure element. Film growth at 35 °C exhibited a substrate-enhanced mechanism, characterized by faster film growth for the first ~125 ALD cycles, where substantial deposition is occurring on the original substrate surface (GPC (growth-per-cycle) = 1.3 Å on SiO2/Si, and 1.0 Å on H-Si), and slower film growth (GPC = 0.40 Å on SiO2/Si, and 0.27 Å on H-Si) after ~125 cycles, once much of the initial substrate surface has been covered. Films deposited using 500-2000 ALD cycles were shown to be continuous by SEM. The use of less than 250 cycles afforded discontinuous films. However, in this initial growth phase, when deposition is occurring primarily on the original substrate surface, in-situ surface pre-treatment by Sb(SiMe3)3 or SbCl3 (50 x 0.4 or 0.8 s pulses), followed by the use of longer precursor pulses (0.4 or 0.8 s) during the first 50 ALD cycles resulted in improved nucleation. For example, on H-Si, a continuous 6.7 nm thick film was produced after initial pre-treatment with 50 x 0.8 s pulses of SbCl3, followed by 50 ALD cycles using 0.8 s pulses. The use of longer ALD pulses in the first 50 ALD cycles following surface pre-treatment is likely required in order to achieve complete reactivity with an increased density of reactive surface sites. Boranes featuring bulky silyl or sterically unencumbered trimethylgermyl groups, in combination with a stabilizing dimethylamido group, were pursued as potential precursors for ALD of elemental boron. This ALD process would employ a boron trihalide (BX3; X = F, Cl, Br, I) co-reactant, exploiting the thermodynamically favourable formation of tetrel-halide bonds as a driving force. This work required multistep syntheses of alkali metal silyl reagents, {(Me3Si)3Si}Li(THF)2 (3-1) and tBu3SiNa(THF)n (3-2), and previously un-isolated [Me3GeLi(THF)2]2 (3-3), and their reactions with B(NMe2)Cl2 (3-4). The boranes {(Me3Si)3Si}2B(NMe2) (3-8) and (tBu3Si)(Me3Ge)B(NMe2) (3-12) were successfully synthesized, spectroscopically and crystallographically characterized, and assessed for their suitability as precursor molecules for boron ALD. Unfortunately, deposition attempts on SiO2/Si using 3-8 and BCl3 led to minor film growth (GPC = 0.01 Å). However, the enhanced volatility and solution-state reactivity of 3-12 in comparison to 3-8 makes it a promising precursor candidate for future ALD reactor studies. Attempts to synthesize bis(trimethylgermyl)(dimethylamido)borane from the 2:1 reaction of 3-3 with 3-4 resulted in the formation of a lithium trigermylamidoborate, {(Me3Ge)3B(NMe2)}Li(THF)2 (3-13). ALD can give rise to uniquely uniform and conformal ultra-thin films, but voids often remain after attempted filling of narrow high-aspect-ratio trenches. To achieve void-free trench-filling, ALD (or CVD; chemical vapour deposition) methods which deposit a flowable material are desirable, and this initially-deposited material can be converted to the target material (e.g. a metal oxide) by post-deposition annealing, or potentially at the deposition temperature on a longer timescale than flowable behaviour. In this work, a new HfO2 ALD process was developed using [Hf(NMeEt)4] in combination with β- hydroxyisovaleric acid (IVA; CMe2(OH)CH2CO2H) that introduces the potential for flowability. Self-limiting growth was observed at 100, 250, and 300 °C, with a GPC of 1.5- 2.2 Å on planar SiO2 substrates. Films deposited at 100 °C consisted of amorphous HfO2 with significant carbon content (~22 at%) and <1 at% nitrogen. After annealing at 400 °C in vacuo for 1 hour, the films were composed of amorphous HfO2 with low (<1 at%) carbon content. The co-reactant in this work, β-hydroxyisovaleric acid, was chosen with the following criteria in mind: Firstly, the carboxylic acid group may be sufficiently acidic to cleave linkages between chemisorbed hafnium species and the surface, generating flowable non-surface-tethered hafnium carboxylate species (with low volatility, so that they are not lost from the surface). Secondly, the hydroxyl groups of the ligands can potentially serve as reactive sites for the hafnium precursor delivered in the next pulse. Thirdly, fairly low-energy pathways should exist for deprotonated IVA ligands to decompose to generate oxide or hydroxide ligands with release of volatile by-products, such as CO2 and isobutene, or acetone and ketene. Experiments to gain insight into the nature of reactivity between [Hf(NMeEt)4] and IVA and a structurally similar carboxylic acid are described. These include (a) solution-state reactions between [Hf(NMeEt)4] and IVA or pivalic acid (tBuCO2H), with formation of [H2NMeEt]2[Hf(κ2-O2CCH2CMe2OH)2(κ2- OC(O)CH2CMe2O)2] (4-1) and [Hf5(μ3-O)4(κ2-O2CtBu)4(μ-O2CtBu)8] (4-2), (b) attempted ALD using pivalic acid (which lacks a hydroxyl group) in place of IVA, and (c) roomtemperature solution reactions between [Hf(NMeEt)4] and 4 equiv. of IVA to form 4-1, followed by removal of volatiles, heating at 200 °C, and volatile/soluble product analysis by NMR spectroscopy and GC-MS headspace analysis. Compounds 4-1 and 4-2 were isolated and crystallographically characterized. Heteroleptic zirconium(IV) complexes were designed, synthesized, spectroscopically and crystallographically characterized, and assessed as potential precursor molecules to enable flowable ZrO2 ALD. The envisaged process would operate via the deposition of oligomeric, one-dimensional chains that, if grown untethered on a functionalized substrate, could potentially flow to the bottoms of trenches. Reaction of one equivalent of H2(acen), H2(cis-Cyacen) or H2(trans-Cyacen) with [Zr(CH2SiMe3)4] at room temperature afforded [Zr(acen)(CH2SiMe3)2] (5-1), [Zr(cis-Cyacen)(CH2SiMe3)2] (5-2) or [Zr(trans-Cyacen)(CH2SiMe3)2] (5-3), respectively (acen = C2H4(NCMeCHC(O)Me)2; Cyacen = 1,2-C6H10(NCMeCHC(O)Me)2). These alkyl compounds are trigonal prismatic in the solid state, and whereas 5-1 and 5-3 decomposed without sublimation above 120 °C (5-10 mTorr), 5-2 sublimed in >95% yield at 85 °C (5-10 mTorr). However, heating solid 5-2 at 88 °C under static argon for 24 hours resulted in extensive decomposition to afford H2(cis-Cyacen) and SiMe4 as the soluble products. Compound 5-2 reacted cleanly with two equivalents of tBuOH to afford [Zr(cis-Cyacen)(OtBu)2] (5-4), but excess tBuOH caused both SiMe4 and H2(cis-Cyacen) elimination. The 1:1 reaction of H2(acen) with [Zr(NMeEt)4] did not proceed cleanly, and 8-coordinate [Zr(acen)2] (5-5) was identified as a by-product; this complex was isolated from the 2:1 reaction. A zirconium amido complex, [Zr(acen)(NMeEt)2] (5-6) was accessed via the reaction of 1 with two equiv. or excess HNMeEt, but decomposed readily in solution at room temperature. More sterically hindered [Zr(acen){N(SiMe3)2}2] (5-7) was synthesized via the reaction of [Zr(acen)Cl2] with two equivalents of Li{N(SiMe3)2}, but was also thermally unstable as a solid and in solution at room temperature. Compounds 5-1 to 5-3, 5-5 and 5-7 were crystallographically characterized. / Dissertation / Doctor of Science (PhD) / The focus of this work is the development of new processes to deposit ultra-thin films of main group elements and transition metal oxides. The deposition method utilized in this work is atomic layer deposition (ALD), which involves the use of a precursor molecule (which contains the target element) and a co-reactant. These chemical species must be appropriately reactive towards one another, and display adequate volatility and thermal stability. The feasibility of a precursor/co-reactant combination can be assessed using solution-state reactivity studies. For main group element ALD, silyl-containing compounds (E(SiR3)3, E = Sb, B) have been investigated as precursors in combination with EX3 (X = F, Cl, Br, I) coreactants, due to the potential for thermodynamically favourable Si-X bond formation to drive the required surface-based reactions. For metal oxide ALD (MO2; M = Hf, Zr), new ALD methods have been proposed to enable gap-free filling of narrow trenches on the surface of a silicon wafer. This work involved the design, synthesis, and evaluation of new ALD precursor molecules and reactions, ALD reactor studies for thin film deposition, and characterization of the resulting films.

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Yes / Active packaging consisting of polyethylene terephthalate (PET) trays coated with a Citrus extract, without and with plasma pre-treatment, can reduce lipid oxidation in cooked meat. The mechanism of action of the packaging was investigated by quantifying the extent of transfer of antioxidant components from the active packaging into cooked turkey meat. Kinetic studies revealed the affinity for water of phenolic compounds and carboxylic acids in the Citrus extract, suggesting their diffusion into the water phase of the meat facilitated their antioxidant effect. Analysis by high-performance liquid chromatography permitted the identification of carboxylic acids and flavanones as major components of the extract. Their quantification in meat after contact with the trays revealed a release of 100% of the total coated amount for citric acid, 30% for salicylic acid, 75% for naringin and 58% for neohesperidin, supporting the release of these components into cooked meat as a mechanism of action of the antioxidant active packaging.

No description available.

Steel producers use various organic and inorganic coatings to protect cold-rolled steel (CRS) sheets from corrosion during shipment and storage. It is well known that CRS sheets can be protected from corrosion by galvanizing, phosphating, chromating, topcoating with organic, or their combinations. The chromate rinsing is particularly effective for preventing white rusting of galvanized steel. But there is an increasing interest in a replacement for the chromating process because of environmental and health concerns. The objective of the present work is to develop a chrome-free conversion coating for steel sheets. Various carboxylic acids and their salts have been studied for coating phosphated electrogalvanized (EG) steel sheets, including 10-undecenoic acid (UA), oleic acid (OA), and other fatty acids such as stearic acid (SA) and palmitic acid (PA). When they were used alone, or subsequently coated with resin, they could produce a highly hydrophobic surface and improve the corrosion resistance. Thiols such as 1-octadecanethiol (ODT) can form a self-assembled monolayer on metal substrates. This close-packed monolayer could provide an excellent corrosion resistance for EG steel sheets. It was capable of withstanding 50~60 hours of salt spray test (SST) although its thickness was only a few nanometers. The EG steel itself usually started rusting only after 2~4 hours of salt spray. In another coating system, thiols were mixed with a conventional resin to improve the corrosion resistance of EG steel. This new technique gave 100~120 hours of corrosion resistance. When the resin was applied directly on EG steel surface, its corrosion resistance was less than 72 hours. It was shown that further optimization of this technique increased the corrosion resistance to 200 hours and more in the standard SST. / Ph. D.

The scope of this research entailed the synthesis of novel polyorganosiloxanes with pendent phosphine, phosphine oxide, nitrile and carboxylic acid moieties. Such polysiloxanes were prepared with controlled concentrations of both the polar moieties and hydrido or vinyl pendent crosslinkable sites to afford precursor materials for well-defined networks. The intention was to generate stable microcomposite dispersions with very high concentrations of polar thermally conductive fillers. Lightly crosslinked elastomeric networks with controlled amounts of polar moieties were prepared via a hydrosilation curing mechanism. High concentrations of thermally conductive micro-fillers were dispersed throughout the resins and the microcomposites were investigated as thermally conductive adhesives. Random polysiloxane copolymers containing controlled number average molecular weights (Mns) and compositions with systematically varied concentrations of hydridomethylsiloxy- or vinylmethylsiloxy- units were prepared via ring-opening equilibrations of cyclosiloxane tetramers. These precursors were functionalized with precise concentrations of polar pendent moieties via hydrosilation (nitrile) or free radical addition reactions (phosphine and carboxylic acids). Valuable additions to the family of polysiloxanes were prepared by oxidizing the phosphine moieties to form phosphine oxide containing polysiloxanes. Defined concentrations of residual hydrido- or vinyl- reactive sites were crosslinked via hydrosilation to yield elastomeric adhesives. Specific interactions between the nitrile and phosphine oxide substituted polysiloxanes and the acidic proton of chloroform were shown using 1H NMR. The magnitude of the shift for the deshielded chloroform proton increased with the degree of hydrogen bonding, and was larger for the phosphine oxide species. The polar polysiloxane resins were filled with high concentrations of thermally conductive fillers including silica-coated AlN, Al spheres, BN and Ag flake, then hydrosilated to form microcomposite networks. Microcomposite adhesive strengths, thermal properties (glass transition temperature (Tg) and high temperature stability), and thermal conductivities were studied. An unfilled polysiloxane network containing only 15 mole percent phosphine oxide exhibited a dramatic improvement (46 N/m) in adhesive strength to Al adherends relative to a control polydimethylsiloxane network (2.5 N/m). Importantly, stable polysiloxane micro-dispersions were obtained with up to 67 volume percent (86 weight percent) silica-coated AlN. TEM data confirmed the dispersion homogeneity and XPS demonstrated that the particle surfaces were well-coated with the functionalized polysiloxanes. A microcomposite comprised of 67 volume percent silica-coated AlN and a polysiloxane containing only 9 molar percent nitrile groups had a thermal conductivity of 1.42 W/mK. The glass transition temperatures of the microcomposites were controlled by the amounts of polar functional moieties on the resins and the network crosslink densities. All of the microcomposites exhibited Tgs lower than -44°C and the materials remained stable in dynamic TGA measurements to approximately 400°C in both air and nitrogen. / Ph. D.

Ce travail s’inscrit dans le cadre de la migration des éléments radiotoxiques dans la géosphère, en contexte de stockage géologique futur de déchets nucléaire. Pour mieux comprendre les phénomènes de rétention, nous avons choisi d’étudier la spéciation de l’ion uranyle (modèle d’un ion radiotoxique mobile) sur la silice (modèle d’oxyde) en présence d’acides monocarboxyliques à courte chaîne (un des modèles des matières organiques naturelles et surtout caractéristiques des produits de dégradation de la cellulose contenue dans les déchets technologiques). La démarche adoptée consiste à associer une étude macroscopique et une analyse structurale, afin d’accéder par modélisation, aux valeurs des constantes associées des équilibres de rétention mis en jeu.Les courbes de sorption réalisées en fonction du pH en présence d’acides organiques nous montrent une relation compétitive pour complexer l’ion uranyle entre les ligands organiques et des sites de surface de la silice. D’ailleurs, plus longue est la chaîne carbonée, plus évidente est cet effet de compétition.La caractérisation structurale des complexes de surface formés a été réalisée par ATR – FTIR et par SLRT. Ces deux techniques montrent que la présence d’acides organiques change l’environnement de l’uranyle sorbé par rapport au système uranyle/silice, ainsi un complexe ternaire de surface « silice-uranyle-organique » ne se sorbe qu’en présence d’acide acétique ou propanoïque. La coordination « chelating-bidentate » entre l’uranyle et le carboxylate, est mise en évidence par spectroscopie Infrarouge. L’ensemble de ces données expérimentales permet de simuler de manière très cohérente des courbes de sorption en utilisant le modèle de complexation de surface à capacité constante. / Understanding the migration behaviour of radionuclides is essential for a reliable long-term safety assessment of nuclear waste disposal sites. In this study, we focus on the sorption behaviour of uranyl ion (model of hexavalent actinides) on silica gel (reference oxide presents in soils) in the presence of the simplest monocarboxylic acids (to model the organic matters or to be degradation products of cellulose issued from nuclear industry). Moreover, no investigation has been reported on their interactions in previous studies, while the main part of studies on ternary systems concerns the effect of humic or fulvic substances. In this work, the studies of uranyl ion and acids uptake in sorption systems have been performed by combining the macroscopic sorption data and the spectroscopic informations of the surface complexes. The sorption edges as function of pH for different systems indicate that the increase of organics concentration results in a decrease of uranyl ion retention in the following order: propionate > acetate > formate, which can be interpreted as their complexing capacity with uranyl ion in solution. ATR – FTIR and TRLFS are applied to carry out the structural information of sorbed uranyl ion and carboxylic acids at the silica/electolyte interface. Both techniques show a good agreement that the presence of acids changes the environments of sorbed uranyl and suggest the existence of “silica-uranyl-organic” ternary surface complexe when acetic or propionic acid presents. Infrared spectroscopy shows also that the coordination between uranyl ion and carboxylate group is “chelating-bidentate” coordination type. Based on these structural investigations, the sorption edges are simulated effectively and the reaction constants are then obtained by using the constant capacitance surface complexation model.

The primary reason for incorporating pigments into plastic materials is to impart the desired colour to finished articles. Some pigments however, may interact with the polymer leading to unexpected deleterious effects. Organic pigments, especially phthalocyanines, are favourable for their brilliant shade but are also well known for causing part distortion or warpage. This causes problems in parts which require good dimensional stability such as crates, containers, trays, caps and closures. Despite that, there are not many published studies on the root cause and mechanism of warpage induced by the pigment. Hence, the objective of this research is to study the influence of such pigments on the dimensional stability, crystallisation behaviour and morphology of polyethylenes in order to have a better understanding on the mechanism of warpage, which could possibly lead to a solution in overcoming this problem.

The surface behavior of biologically or atmospherically relevant chemical compounds in aqueous solution has been studied using surface-sensitive X-ray photoelectron spectroscopy (XPS). The aim is to provide information on the molecular-scale composition and distribution of solutes in the surface region of aqueous solutions. In the first part, the distribution of solutes in the surface region is discussed, where in particular single molecular species are studied. Concentration-dependent studies on succinic acid and various alkyl-alcohols, where also parameters such as pH and branching are varied, are analyzed using different approaches that allow the quantification of surface concentrations. Furthermore, due to the sensitivity of XPS to the chemical state, reorientation of linear and branched alkyl-alcohols at the aqueous surface as a function of concentration is observed. The results are further discussed in terms of hydrophilic and hydrophobic interactions in the interfacial region, where the three-dimensional hydrogen bonded water structure terminates. In the second part, mixed solutions of compounds, both ionic and molecular, are inspected. Again concentration, but also co-dissolution of other chemical compounds, are varied and differences in the spatial distribution and composition of the surface region are discussed. It is found that the guanidinium ion has an increased propensity to reside at the surface, which is explained by strong hydration in only two dimensions and only weak interactions between the aromatic π-system and water. Ammonium ions, on the other hand, which require hydration in three dimensions, are depleted from the surface region. The presence of strongly hydrated electrolytes out-competes neutral molecules for hydrating water molecules leading to an enhanced abundance of molecules, such as succinic acid, in the interfacial region. The partitioning is quantified and discussed in the context of atmospheric science, where the impact of the presented results on organic loading of aerosol particles is emphasized.

DERIVATIVES OF 5-ALKYLPYRAZINE-2-CARBOXYLIC ACID AS POTENTIAL ANTI-INFECTIVES HALÍŘOVÁ MARTINA Department of Pharmaceutical Chemistry and Drug Analysis, Faculty of Pharmacy in Hradec Králové, Charles University, Czech Republic In our previous study, we have demonstrated that 5-alkylamino-N- phenylpyrazine-2-carboxamides with longer alkyl chain (C5-C8) exerted micromolar growth inhibition activity against M. tuberculosis H37Rv. We speculated that the long alkylamino chain could facilitate the penetration of lipophilic mycobacterial cell envelope. To test this hypothesis, we performed the amino to methylene isosteric exchange and designed a series of 5-alkyl-N-phenylpyrazine-2-carboxamides. 5- Alkylpyrazine-2-carboxylic acids (5-Ak-POA) were prepared by homolytic alkylation of commercially available pyrazine-2-carbonitrile by respective alkanoic acid, followed by hydrolysis of the carbonitrile group. Final derivatives were prepared by CDI mediated coupling of 5-Ak-POA with corresponding aniline at RT. Final compounds were described by melting point, elementary analysis, IR spectroscopy and 1 H, 13 C NMR. Then they were tested in vitro for antimycobacterial activity against M. tuberculosis H37Rv and several non-tuberculous mycobacterial strains. Several compounds exerted MIC of 3.13-6.25 µg mL-1 ....