NMR and Raman spectroscopic study of as-sprayed coatings and coatings incubated in simulated body fluid

Hydroxylapatite (HA) is a frequently used bioceramic material for replacement of bone matter subjected to low loading conditions, for osseoconductive coatings on implants and for utilisation as a drug carrier. Plasma spraying is widely used to coat hydroxylapatite onto titanium alloys in hip endoprostheses. However, the high temperature of the plasma jet changes the crystallinity and decomposes hydroxylapatite. This affects in turn its bioconductivity. In this study, HA was coated onto Ti6Al4V substrates by atmospheric plasma spraying (APS). Also, a bionert TiO2 bond coat was applied between the HA coating and the titanium alloy. By means of some sensitive analytical techniques, notably nuclear magnetic resonance (NMR) and Raman spectroscopy, the structural decomposition of HA during plasma-spraying and the in vitro reconstruction mechanisms of distorted (oxy)hydroxylapatite to well-ordered hydroxylapatite were investigated. The advantages of such a bond coat were also shown.thesi

Halometallate ionic liquids – revisited

Ionic liquids with chlorometallate anions may not have been the first ionic liquids, however, it was their development that lead to the recognition that ionic liquids are a distinct, and useful, class of (functional) materials. While much of the phenomenal interest and attention over the past two decades has focussed on ‘air and water stable’ ionic liquids, research and application of chlorometallate systems has continued unabated albeit largely out of the main spotlight. The defining characteristic of chlorometallates is the presence of complex anionic equilibria, which depend both on the type and on the concentration of metal present, and leads directly to their characteristic and individual properties. Here, we review the experimental techniques that can be applied to study and characterise the anion speciation in these ionic liquids and, using recent examples, illustrate how their applications base is evolving beyond traditional applications in Lewis acidic catalysis and electrochemistry through to uses as soft and component materials, in the ionothermal synthesis of semiconductors, gas storage systems and key components in the development of biomass processing

Investigation into the thermal dehydroxylation and decomposition of hydroxylapatite during atmospheric plasma spraying: NMR and Raman spectroscopic study of as-sprayed coatings and coatings incubated in simulated body fluid

Hydroxylapatite (HA) is a frequently used bioceramic material for replacement of bone matter subjected to low loading conditions, for osseoconductive coatings on implants and for utilisation as a drug carrier. Plasma spraying is widely used to coat hydroxylapatite onto titanium alloys in hip endoprostheses. However, the high temperature of the plasma jet changes the crystallinity and decomposes hydroxylapatite. This affects in turn its bioconductivity. In this study, HA was coated onto Ti6Al4V substrates by atmospheric plasma spraying (APS). Also, a bionert TiO2 bond coat was applied between the HA coating and the titanium alloy. By means of some sensitive analytical techniques, notably nuclear magnetic resonance (NMR) and Raman spectroscopy, the structural decomposition of HA during plasma-spraying and the in vitro reconstruction mechanisms of distorted (oxy)hydroxylapatite to well-ordered hydroxylapatite were investigated. The advantages of such a bond coat were also shown

Synthesis and Characterization of Bimetallic Zintl Clusters and their Use in the Fabrication of Intermetallic Nanoparticles

In this thesis, the synthesis, characterization and applications of bimetallic Zintl clusters are explored. Zintl ions are polyanions of main group elements, primarily of the heavier elements of groups 14 and 15. The closo-Sn9Ir(cod)3-, Sn9Rh(cod)3-, and Pb9Ir(cod)3- ions were prepared from precursors E94- (E = Sn, Pb), [M(cod)Cl]2 (M = Rh, Ir) and 2,2,2-crypt in ethylenediamine/toluene solvent mixtures. The clusters were isolated and characterized via NMR spectroscopy and single-crystal X-ray diffraction studies. The closo-E9Ir(cod)3- ions are the first known Ir(I) Zintl clusters and are examples of isostructural Sn/Pb homologues. All three complexes have 22-electron, bicapped square-antiprismatic structures and pseudo-C4v point symmetry with the Ir(cod) and Rh(cod) vertices attached in an η4 fashion. The Sn9Rh(cod)3- ion possesses 119Sn NMR chemical shifts that are consistent with other known Sn94- transition metal derivatives. The structural studies and 1H and 13C NMR studies showed significant charge transfer to the cod ligands. Novel Rh@Sn123- and Rh@Pb123- ions have been prepared and isolated in the solid state and the latter has been studied via 207Pb NMR. The ions are 26-electron clusters with near perfect icohsahedral Ih point symmetry. Additionally, Ir@Pb123- and the previously isolated Ir@Sn123- ion [Fässler et al. 2010, Chem. Eur. J.] were detected for the first time via 207Pb and 117Sn NMR, respectively. The 207Pb NMR of Rh@Pb123- and Ir@Pb123- have the most downfield 207Pb signals known to date, due to their σ-aromaticity. The Sn94- and As73- Zintl ions were shown to be effective reducing agents in the synthesis of three novel transition metal complexes. The synthesis and crystallographic characterization of the novel [Rh2H(PPh2)2(PPh3)3]-, Co3(CO)73-, and [(C3H7N2O)3Ir4(CO)9]3- ions are reported for the first time and cannot be prepared using traditional reducing agents. Controlled I2 oxidations of preformed Zintl clusters Pt@Sn9Pt(PPh3)2- and Sn9Ir(cod)3-, give well ordered tin-rich intermetallic nanoparticles of PtSn4 and Ir3Sn7, respectively. The intermetallics were characterized by HR-TEM and XRD analysis. Both clusters have strong structural similarities with the final intermetallic, which appears to be an important factor in determining the phase of the resulting intermetallic nanoparticles. Despite the 1:9 (Ir:Sn) atomic ratio of the Sn9Ir(cod)3- cluster, ordered Ir3Sn7 nanoparticles were formed instead of the compositionally-similar IrSn4 phase. PtSn4 is difficult to prepare by traditional methods and isolate due to the formation of other known Pt-Sn phases, such as PtSn, PtSn2 and Pt3Sn

Sorption of trivalent actinides onto gibbsite, γ-alumina, and kaolinite : A spectroscopic study of An(III) interactions at the mineral-water interfaces

This Ph.D. thesis concerns investigations on the interactions of trivalent actinides with the mineral phases γ-alumina, gibbsite, and kaolinite. Spectroscopic methods, namely time-resolved laser fluorescence spectroscopy (TRLFS) and nuclear magnetic resonance (NMR) have been employed together with macroscopic sorption investigations to obtain molecular level process understanding of the solid-water interface reactions occurring in the mineral suspensions. Results obtained in the macroscopic sorption investigations with gadolinium(III) and the spectroscopic (TRLFS) investigations with curium(III) onto the aluminum hydroxide phase gibbsite, α-Al(OH)3 showed that two interaction mechanisms, inner sphere surface complexation and incorporation, are required to explain the metal ion speciation at the gibbsite surface over the investigated pH range 5-11.5. Sorption of Gd3+/Cm3+ commences at pH values close to 5 through formation of an inner sphere surface complex. When the pH is raised towards the alkaline pH range another inner sphere complex can be detected from the acquired TRLFS data. The continuous increase of suspension pH, however, also influences the solubility of aluminum with a direct impact on the trivalent metal ion speciation. Upon moving from higher aluminum solubility regions in the acidic pH range towards the solubility minimum at pH 6.3, aluminum hydroxide precipitates from oversaturated solutions and consequently incorporates surface bound curium on the gibbsite surface. When further increasing the pH towards the alkaline pH range, aluminum solubility increases again which results in dissolution of the incorporating precipitate uncovering the curium surface complex. This sorption behavior has not been encountered previously in investigations with other aluminum oxide/hydroxide minerals as sorbent phases for trivalent metal ion attachment. Identification of an incorporated curium species as a consequence of pH variations is a clear proof that mineral surfaces cannot be considered as inert with regard to chemical variations as done in many studies. In macroscopic (Eu3+) and TRLFS (Cm3+) sorption investigations with kaolinite as sorbent phase, both outer sphere and inner sphere surface complexes could be identified. Outer sphere complexation was pronounced in background electrolyte concentrations of 1 mM NaClO4, while outer sphere attachment was found only for low (less than 10-7 M) europium concentrations on a natural kaolinite batch and not at all in synthetic kaolinite suspensions when 100 mM NaClO4 was used in the experiments. Three inner sphere curium complexes differing only in the degree of hydrolysis were found to dominate the speciation over a large pH range (5.5-11.5). These species were assigned to >Cm(H2O)52+, >Cm(OH)(H2O)4+ and >Cm(OH)2(H2O)3 based on fluorescence lifetime data and they correlate very well in terms of emission peak positions and fluorescence lifetimes values to curium species found on other clay mineral surfaces. Above pH 11.5 a further curium complex that could not be assigned to a pure hydrolyzed curium surface complex became prevailing. The TRLFS experiments showed that the dissolution of kaolinite in the alkaline pH-range (>10) resulted in the formation of a ternary complex between surface-sorbed curium and dissolved silicates in solution. Thus, the dissolution of the sorbent phase could again be shown to influence the metal ion speciation verifying the need for spectroscopic investigations for a correct assignment of the formed complexes at the solid/water interface. The sorption of diamagnetic yttrium(III) and paramagnetic europium(III) on the various surface hydroxyl groups of γ-alumina (γ-Al2O3) and kaolinite was investigated in NMR studies. Upon Eu3+/Y3+ attachment onto the mineral surfaces the 1H NMR signal could be seen to decrease. In difference spectra produced by subtracting the acquired proton spectra of samples with high metal ion concentrations from spectra of clean mineral samples or samples with lower metal ion loadings, a manifold of surface hydroxyl groups influenced by the metal ion attachment to the surface could be identified. These surface groups could be assigned to doubly coordinated Al2-OH and singly coordinated Al-OH groups on the respective mineral surfaces. In the γ-alumina study the wide distribution of chemically very similar OH protons was attributed to variations in O-H bond lengths and to variations in the Al coordination (AlIV/AlVI). In the kaolinite study removed protons in the metal ion sorption reaction were assigned to singly coordinated Al-OH groups at the kaolinite edge surfaces. In addition, indications of trivalent metal ion attachment to bridging Al-OH-Al groups at the gibbsite-like basal plane of the mineral were obtained.Det använda kärnbränslet från de finska kärnreaktorerna kommer att slutförvaras i berggrunden i Olkiluoto. Syftet med slutförvaret är att isolera det radioaktiva avfallet från den levande naturen i flera hundratusen år. I slutförvaret kommer det använda kärnbränslet att skyddas av tre barriärer: kopparkapseln, bufferten och själva urberget. I denna avhandling har växelverkningar mellan trevärda aktinider som förekommer i det använda kärnavfallet samt mineralfaserna γ-alumina [γ-Al2O3], gibbsit [α-Al(OH)3] och kaolinit [Al2Si2O5(OH)4] undersökts. Syftet med arbetet har varit att erhålla information om hur dessa aktinider adsorberas på mineralytorna, vilket i berggrunden kommer att fördröja eller hindra dessa radioaktiva ämnens transport med grundvattnet upp mot markytan. För att erhålla information om de processer som sker vid mineral/vatten gränsytan har de spektroskopiska metoderna tidsupplöst laserinducerad fluorescensspektroskopi (TRLFS) samt kärnmagnetisk resonansspektroskopi (NMR) tillämpats. De spektroskopiska undersökningarna har kompletterats med makroskopiska, så kallade batchundersökningar, där trevärda lantanider har används som analoger till de radioaktiva aktiniderna. Sorptionsundersökningarna med lantaniden gadolinium(III) eller europium(III) och de spektroskopiska (TRLFS) undersökningarna med aktiniden curium(III) har visat att de trevärda metallerna adsorberas på mineralytorna gibbsit och kaolinit som såkallade innersfärkomplex, där en kemisk bindning mellan metallen och mineralytan bildas. Dessutom sker adsorptionen av Eu3+/Cm3+ även som yttersfärkomplexbildning på kaolinitytan i det sura pH-området. Yttersfärkomplexbildning är en elektrostatisk växelverkan mellan den negativa mineralytan och den positiva metalljonen. I TRLFS undersökningarna kunde den kontinuerliga pH-ökningen från pH 5 till 11.5 under experimenten ses påverka gibbsitlösligheten i mineralsuspensionerna med en direkt inverkan på den trevärda metalljonens speciation. Då experimenten utfördes från ett pH-område med högre aluminiumlöslighet till ett med lägre löslighet, skedde en utfällning av aluminiumhydroxid från den övermättade lösningen. Denna fällning inkorporerade det innersfäradsorberade curiumkomplexet vid gibbsitytan. I kaolinitstudierna kunde ett curium-innersfärkomplex mellan adsorberat curium på kaolinitytan samt lösta silikater i mineralsuspensionen, som uppkommit som följd av en märkbar upplösning av kaolinitmineralen då pH överskrider 10, påvisas. Identifieringen av den inkorporerade curium-specien på gibbsitytan och komplexet mellan curium och lösta silikater på kaolinitytan är ett tydligt bevis på att mineralytor inte kan anses vara inerta med avseende på kemiska variationer, utan förändringar i de kemiska förhållandena under undersökningarna måste beaktas. Dessutom framhävs behovet av spektroskopiska undersökningar för en korrekt beskrivning av de bildade komplexen vid mineral/vatten gränsytan. Adsorptionen av diamagnetiskt yttrium(III) och paramagnetiskt europium(III) på de olika yt-hydroxylgrupperna hos γ-alumina (γ-Al2O3) och kaolinit undersöktes i NMR-studier. Vid adsorption av Eu3+/Y3+ på mineralytorna, kunde protonsignalen i samtliga 1H NMR spektra ses avta i jämförelse med den erhållna protonsignalen från de rena mineralerna. 1H NMR signalens avtagande sker som följd av metallkomplexbildningen på ytan som samtidigt lösgör en eller flera hydroxylprotoner från mineralytan. Hydroxylgrupper på de respektiva mineralytorna som påverkades av sorptionreaktionen identifierades som dubbelt koordinerade Al2-OH grupper, där en hydroxylgrupp är förknippad med två aluminiumatomer i mineralstrukturen, samt enkelt koordinerade Al-OH grupper, där varje hydroxyl är förknippad med enbart en aluminiumatom. Erhållna NMR spektra visade dessutom att det är fråga om ett flertal, mycket liknande hydroxylgrupper som deltar i sorptionsreaktionen

Design and characterization of aromatic thermosetting copolyester resin for polymer matrix nanocomposites

This study presents the development of multifunctional polymer nanocomposite systems utilizing aromatic thermosetting copolyester resin enriched with various forms of nanofiller particles. The molecular weight and crosslinking functionality of precursor oligomers during condensation polymerization reaction regulate thermal-mechanical properties of self-generated foam morphologies. Aluminum foam layered aromatic thermosetting copolyester foam sandwich structures demonstrate outstanding impact energy absorption characteristics. High-performance nanocomposite foams, incorporating homogenously distributed carbonaceous nanoparticles, display significantly improved thermophysical properties that outperform state-of-the-art configurations. Periodically-functionalized self-assembled shish-kebab structures develop within an aromatic resin dip-coated graphene fiber system through an epitaxial step-growth polymerization process. Graphene nanoplatelet particles conjugate with precursor oligomers during in situ polymerization process forming electrically percolated network domains which enable controllable conductivity for nanocomposite structures. The interfacial attachment mechanism between carbonaceous particles occurs via oxygen-bearing functional groups, which establishes covalent bonding with cure advancing crosslinking polymer network and modifies the glass transition region characteristics. The aromatic resin forms an interfacial liquid crystalline mesophase domain around graphene nanoplatelets, which uniquely displays a thermally reversible characteristic with shape memory effect. Self-luminescent dielectric silicon nanoparticles homogenously disperse into the aromatic matrix without neither losing their luminescent properties nor deteriorating chemical configuration of the polymer network. The neat and nanocomposite structures preserve their physical and chemical properties following direct exposure to aggressive environmental aging conditions. Bioactive nanofiller particles reinforced bionanocomposites hold a promise as a reconfigurable bone replacement material, for which interfacial coupling with nanoparticles enables more deformation tolerant nanocomposite matrix. The aromatic resin can afford high-temperature enabled solid-state dynamic covalent bond exchange reaction between two similar surfaces, which enables a reversible bonding scheme to develop multifunctional reconfigurable in-space architectures for deep-space missions. The bonding/debonding mechanism displays >50 times repeated cycles through predominantly cohesive failure along with high glass transition temperature and bonding strength required for relevant application requirements. The solid-state bonding concept can also be utilized to join similar/dissimilar polymer composites and metal articles permanently. Via controlled process time, temperature and pressure, aromatic resin displays relatively high bonding strengths viable from cryogenic temperatures to elevated temperatures. The bonding approach can be utilized to produce lightweight fuselage structures for spacecraft without necessitating additional joining mechanisms. Covetics are a novel class of carbon-metal nanomaterials for which in situ generated arc discharge during fabrication induces a chemical conversion reaction converting amorphous carbon to a crystalline graphitic structure which forms an intermetallic covalent bonding with host metal matrix. The covetics exhibit improved thermophysical properties as compared to their parent metals. We provide a comprehensive literature review on the covetics. Aluminum covetics demonstrate significantly improved corrosion potential relative to parent material with no carbon added. Both the hardness and the compressive strength of the aluminum covetic with carbon added are also improved. The carbon particles during covetics fabrication conditions induce structural modifications on intrinsic secondary phases which contribute to the observed changes in corrosion behavior and improvement in mechanical properties

Design, synthesis, characterization and photovoltaic applications of conjugated polymer hybrids containing coordinatively binded semiconducting nanocrystals

Title from PDF of title page, viewed on (February 12, 2015)Dissertation advisor: Zhonghua PengVitaIncludes bibliographic references (pages 158-172)Thesis (Ph.D.) -- Dept. of Chemistry and Dept. of Pharmaceutical Sciences. University of Missouri--Kansas City, 2014Orgainc-inorganic hybrids containing organic conjugated polymers and inorganic semiconducting nanocrystals are fascinating optoelectronic materials which may combine the advantages of both worlds. This dissertation aims at developing rod-coil diblock copolymers with semiconducting nanoparticles coordinatively binded to the coil block. A mechanochemical process has been shown to be a viable and economical approach to prepare uncapped composition tunable semiconducting nanocrystals including CdSexS1-x, CdxZn1-xS, and CdSexTe1-x. The resulting II-IV nanocrystals are chemically homogenous with average sizes lower than ~10 nm, and show a linear lattice parameter-composition relationship. The CdSexS1-x and CdxZn1-xS series show close-to-linear relationship between the bandgap energy and the composition. The ternary CdSe0.25Te0.75, CdSe0.5Te0.5 and CdSe0.75Te0.25 nanocrystals show strong absorption in the NIR range presumably due to both optical bowing effect and Te induced crystal defects. Colloidal CdSe nanocrystals have also been prepared by wet chemical methods with organic capping ligands. Three rod-coil diblock copolymers (DCPs) of the modified poly(3-hexylthiophene)-polystyrene (P3HT-PS) type with different phosphorus-containing functional groups for binding to inorganic nanoparticles have been designed and synthesized. Their corresponding P3HT-PS-CdSe nanocomposites were prepared by ligand-exchange with chemically prepared CdSe nanocrystals. Solid state absorption and fluorescence measurements indicate that the electronic energy states of the polymers are affected by CdSe. Solar cell devices of the three hybrids showed high open circuit voltages of 1.13~1.40 V and improved power conversion efficiencies over devices of the corresponding P3HT-PS diblock copolymers without cluster attachment. The improvement of the PCE is believed to be brought by intimate contact between the P3HT and the CdSe, which enhances the initial charge separation. The device performance is however hampered by the low nanoparticle loading. Carbon nanoparticles (CNPs) with average sizes around 40–60 nm can also be prepared by the high energy ball milling process. The CNPs was utilized as an interfacial layer between TiO2-coated ZnO nanorod arrays and P3HT polymer. They are found to form close and intimate contacts with both TiO2 through carboxylic acid binding and P3HT polymer presumably by way of π–π interaction. The resulting hybrid solar cells showed the highest photocurrent ever reported among the similar type of deviceAbstract -- List of illustrations -- List of tables -- Acknowledgments -- Introduction -- Preparation of uncapped ternary semiconducting nanocrystals by mechanical alloying -- Synthesis of phosphorus-containing polystyrene polystyrene and poly-3-hexylthiophene-polystyrene diblock copolymers -- Phosphine containing diblock copolymer binding to chemically prepared nanocrystals and the related device studies -- Preparation of carbon dots by ball milling and related organic-inorganic hybrid photovoltaic devices studies -- Reference

43rd Rocky Mountain Conference on Analytical Chemistry

Final program, abstracts, and information about the 43rd annual meeting of the Rocky Mountain Conference on Analytical Chemistry, co-sponsored by the Colorado Section of the American Chemical Society and the Rocky Mountain Section of the Society for Applied Spectroscopy. Held in Denver, Colorado, July 29 - August 2, 2001