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Phosphorus containing monomers, bis(3-aminophenyl)methyl phosphine oxide (m-DAMPO) and bis(3-aminophenyl)phenyl phosphine oxide (m-DAPPO), were synthesized and incorporated into a thermoplastic poly(arylene ether imide) based upon 2,2'-bis[4-(3,4-dicarboxyphenoxy)phenyl]propane dianhydride and 1,3-phenylene diamine, in order to study their influence on flame resistance and other properties. DAMPO or DAPPO were quantitatively incorporated in concentrations of 25, 50, 75 and 100 mole percent, using the "one pot" ester-acid method. The number average molecular weights of the prepared materials were controlled to 20,000g/mol by off-setting the stoichiomety and endcapping with phthalic anhydride. This strategy enabled one to distinguish the effects of the phosphine oxide incoporation from the influence of molecular weight. The resulting copolymers demonstrated a significant increase in char yield as a function of the phosphine oxide content, thus suggesting improved fire resistance. Glass transition temperatures similar to the control were determined by DSC analysis. Analysis of the mechanical behavior of the DAMPO system at room temperature showed that tensile strength and elongation at failure values were comparable to the control system, while the DAPPO containing copolymers were surprisingly brittle. The influence of the reactive endgroup on the synthesis, cure behavior and network properties of thermosetting polyetherimides was investigated. Reactive phenylacetylene, acetylene and maleimide terminated poly(ether imide) oligomers were prepared and characterized. Optimal reaction conditions were established to produce fully endcapped oligomers with imidized structures and controlled molecular weight. The phenylacetylene endcapped system was synthesized by a conventional ester-acid method. The acetylene endcapped system was prepared via modified ester-acid method and the maleimide endcapped system was fabricated utilizing an amic-acid route. It was determined that phenylethynyl endcapped polymers could be thermally cured at high temperatures (350-380°C) providing good processibility. The networks exhibited thermal stability, chemical resistance and good adhesion strength, ideal as "primary" bonding adhesives. Acetylene and maleimide endcapped systems were prepared for application as "secondary" bonding materials, meaning that they are cured at a lower temperature than that of the Tg of the primary structure. Lap shear test results indicated good adhesion to titanium when cured at 250°C -280°C. The cured materials showed high glass transition temperatures and good thermal and thermo-oxidative stability as determined by DSC, TGA and DMA. Good chemical resistance was demonstrated via solvent extraction measurements. The influence of molecular weight between crosslinks (Mc) on thermal and mechanical behavior was also investigated. Lower molecular weight oligomers exhibited lower Tg and cure temperatures, whereas the cured networks resulting from lower molecular weight oligomers afforded higher Tg and higher gel fractions, but reduced toughness. / Ph. D.

La thèse consiste en l'étude de la racémisation d'hydrogéno-phénylphosphinates d'alkyle, des molécules centrées sur un phosphore stéréogénique. Pour cela, nous avons synthétisé les composés d'intérêt puis étudié leur cinétique de racémisation en utilisant l'HPLC chirale et la RMN du phosphore. La première étude théorique (SMD//M06-2X/6-31++G**) sur l’énantiomérisation d’un phosphinate d’alkyle après une SN2 par un alcool a montré comme mécanisme le plus favorable une syn-addition de l’alcool sur la double liaison P=O du phosphinate à l’opposé du groupement alkoxy. Les études cinétiques d’inversion du phosphinate d’éthyle dans l’éthanol à reflux ont montré une barrière de 135 kJ.mol-1 en moyenne, en excellent accord avec ce modèle (136 kJ.mol-1). L’ajout de base lors de l’étude cinétique ont montré une accélération de l’inversion avec une barrière maximum mesurée à 121,5 kJ.mol-1 montrant un effet de catalyse basique. Les modèles cinétiques et théoriques réalisés à ce jour ont suggéré que la base activerait l’alcool pour faciliter son addition. Les premiers résultats sur l’influence du groupement alkyle ont montré une dépendance globale de l’inversion à la taille du groupement, mais certains modèles DFT, notamment avec l’adamantyle, n’étaient pas en accord avec cette hypothèse. / This thesis is about the racemization of alkyl hydrogeno-phenylphosphinate, a molecule centered on a stereogenic phosphorus atom. We have synthetized compounds of interest, and studied their kinetic of racemization with chiral HPLC and phosphorus NMR. The first theoretical study (SMD//M06-2X/6-31++G**) about the enantiomerization of alkyl phosphinate after an SN2 with an alcohol have shown that the most favored mechanism was a syn-addition of the alcohol onto the double bond P=O on the opposite side of the alkoxy group. Kinetic studies with ethyl phosphinate in ethanol under reflux have shown an inversion barrier around 135 kJ.mol-1, in excellent agreement with this model (136 kJ.mol-1). The addition of a basic compound during kinetic measurements has shown a decreasing of the barrier to 121.5 kJ.mol-1, showing a catalytic effect. Kinetic and theoretical models have suggested that the mechanism would go through an activation of the alcohol by the basic compound which would facilitate its addition. The first tests about the nature of the alkyl group of phosphinate and alcohol have shown a general dependency of the barrier with the hindrance, but some DFT models, especially with adamantyl, have been in disagreement with this hypothesis.

High molecular weight poly(phenylene sulfide sulfone) (PPSS) homo- and statistical copolymers have been reproducably synthesized using a known, but complex procedure utilizing 4,4'-dichlorodiphenyl sulfone (DCDPS), sodium hydrosulfide, sodium hydroxide, sodium acetate, and deionized water, in NMP at elevated reaction temperatures and pressure. The effect of these variations, e.g., reaction temperatures and times, molar ratios of H2O-to-NaSH, NMP-to-H2O, etc. were investigated. Optimized conditions were defined, which produced Tg as high as 222°C, very high refractive index (1.70), and tough/solvent resistant films could be prepared by melt fabrication. A two-stage decomposition mechanism in air was demonstrated by dynamic thermal gravimetric analysis. The melt stability of PPSS was improved by incorporating thermally stable endgroups, such as diphenyl sulfone, 4-chlorophenylphenyl sulfone, and t-butylphenoxide. The chemical structures of the endgroups were confirmed by 13C and 1H NMR spectra. Compared with mercaptide endcapped PPSS, the new systems showed higher initial degradation temperatures (2% and 5% weight loss), higher char yield at 650°C in air and a more stable melt viscosity at 300°C. A greatly simplified synthesis of both homo and copolymers has been successfully developed using the new A-A or A-B type thiol-functional monomers, such as bis-(4-mercaptophenyl) sulfone, 4-chloro-4'-mercaptodiphenyl sulfone and 4-chloro-4'-mercapto benzophenone, instead of sodium hydrosulfide. A series of high molecular weight triphenyl phosphine oxide and/or diphenyl ketone containing PPSS copolymers were subsequently synthesized from the bis-(4-mercaptophenyl) sulfone by reaction with 4,4'-dichlorodiphenyl sulfone, bis-(4-fluorophenyl) phenyl phosphine oxide, and 4,4'-difluorobenzophenone in DMAc in the presence of K2CO3 at 160°C. The new phosphine oxide containing PPSS copolymers were completely amorphous, showed improved solubility in common organic solvents and exhibited very high char yields in air at 750°C. Surface (XPS) analysis results suggested that the phosphorus moieties in the polymer backbone can form phosphate-like layers on the polymer surface which protects the inner materials from further decomposition in air at high temperatures. The diphenyl ketone containing PPSS copolymers showed very high char yields at 750°C in a nitrogen atmosphere, compared to sulfide sulfone homopolymer and phosphine oxide containing copolymers, possibly because of higher bond energies. Semi-crystalline poly(phenylene sulfide ketone) homopolymers and sulfone containing copolymers with sulfone/ketone mole ratio (S : K) < 25 : 75 were synthesized by a novel base catalyzed self-polycondensation of 4-chloro-4'-mercaptodiphenyl sulfone and/or 4-chloro-4'-mercapto benzophenone in N-cyclohexyl-2-pyrrolidinone (CHP) at 290°C. Amorphous copolymers with S : K ratios > 25 : 75 were prepared in DMAc at 160°C. These materials exhibited an increase in glass transition temperature with increasing sulfone content. TGA and micro cone calorimetry analyses showed that the semi-crystalline materials with high ketone content had much higher char yields and significantly lower heat release rate and total heat release, compared to the poly(phenylene sulfide sulfone) and poly(pheylene sulfide) controls. / 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.

This dissertation research addresses the interrelationships between chemistry and network structure in epoxy networks as well as how mechanical properties of the resulting networks are affected by these relationships. The effects of chemistry and network structure on interphase morphology and performance in vinyl ester/carbon fiber composites have also been investigated on both a macro and nanoscale. Thermosets were prepared with blends of bisphenol-A and novel phosphine oxide based diepoxide oligomers using a siloxane or a novolac crosslinking agent. In the siloxane cured networks the incorporation of the phosphine oxide group yielded networks with increased glass transition temperatures, from 71°C to 92°C, and water absorption, from 1 wt % to 5.5 wt %, due to the polar nature of the phosphine oxide bond. Higher char yields were also observed with the addition of the phosphorus, 27 wt % compared to 11 wt % for bisphenol-A epoxy networks. The bisphenol-A based epoxy/siloxane network was exceptionally ductile with a fracture toughness (K1c) of 2 MPa-m1/2. In networks prepared with the novolac crosslinking agent hydrogen bonding, observed using FTIR, was evident even at temperatures above the network Tg and resulted in increased rubbery moduli with phosphine oxide incorporation. Adhesive strengths to steel increased from ~9.7 MPa with bisphenol-A epoxy to ~13.8 MPa when the phosphine oxide containing epoxy was incorporated into the network. Within carbon fiber/vinyl ester composites, a series of tough ductile thermoplastics and a series of one-phase polyurethanes were investigated as carbon fiber sizings. The three poly(hydroxyether)s resulted in different interphase morphologies due to their respective interdiffusion into the vinyl ester resin. The unmodified poly(hydroxyether) was miscible with the vinyl ester resin at the elevated cure temperatures and adhesion between the fiber and bulk matrix was increased from 28 MPa with unsized fibers to 45 MPa with sized fibers. The carboxylate modified poly(hydroxyether) was also miscible at elevated temperatures, however the interdiffused region was narrower, ~5 mm. This system showed an increase in the fiber/matrix adhesion similar to that found for the unmodified poly(hydroxyether)/vinyl ester system and composite cyclic fatigue durability was improved by ~50 %. Using a poly(hydroxyether ethanolamine) interphase material, which was not miscible with the resin, resulted in a sharp interface. While the adhesion was not improved through the use of this sizing, the composite fatigue durability was still increased by a moderate amount, ~ 25%. The one-phase polyurethanes were dispersible in water with incorporation of a minimum of 0.08 equivalents of N-methyldiethanolamine per mole of diisocyanate. Fatigue durability in composite panels was not improved by the addition of the polyurethane sizings due to the miscibility of the sizing and the matrix. / Ph. D.

Two novel classes of siloxane containing, organic-inorganic block copolymers were prepared using different synthetic approaches. The first copolymers were alternating poly(arylene ether phosphine oxide)-poly(dimethylsiloxane) systems, prepared via oligomeric silylamine-hydroxyl reactions. Secondly, segmented nylon 6,6-poly(dimethylsiloxane) block copolymers were synthesized via a non-aqueous adaptation of the "nylon 6,6 salt" hydrolytic polyamidization, using bis(aminopropyl) dimethylsiloxane oligomer as a co-reactant. Three series of "perfectly" alternating block copolymers were produced from well characterized hydroxyl-terminated poly(arylene ether phosphine oxide) and dimethylamine-terminated poly(dimethylsiloxane) oligomers, in order to investigate both block length and chemical composition effects. Copolymerization in chlorobenzene resulted in high molecular weight materials capable of forming optically clear, nanophase separated films, which displayed unusual morphologies and good mechanical strength. Thermal gravimetric analysis showed high thermo-oxidative stability and increasing char yield with increasing siloxane content. Additional thermal and mechanical investigations provided evidence of selective phase mixing, particularly at shorter block lengths. Surface analysis showed an enrichment of the siloxane blocks at the air-polymer interface in comparison to the bulk state. This behavior increased in proportion to the length of the parent siloxane oligomers. Evaluation of selected optical properties, e.g., refractive indices, revealed linear trends resulting in values of compositionally weighted averages. Conversely, a series of nylon 6,6-siloxane copolymers were produced from the polycondensation of preformed propylamine-terminated poly(dimethylsiloxane)s, solid nylon 6,6 salt and a corresponding amount of adipic acid to afford siloxane-amide semi-crystalline copolymers with siloxane content ranging from 10 to ~45 wt%. The characterization of high molecular weight and covalent siloxane-amide linkages was hindered by insolubility. For example, crystallinity of the nylon 6,6 precluded the use of common solution techniques, while the susceptibility of the siloxane blocks towards ionic redistribution prevented the use of strongly acidic solvents. However, development of a novel analytical technique using solid state 13C NMR and liquid-solid extraction provided evidence for the presence of covalent bonding between the dissimilar oligomer chains. Thermal gravimetric analysis of resultant copolymers revealed an increase in char yield with increasing siloxane content, a preliminary indicator of increased fire resistance, which was supported by subsequent qualitative Bunsen burner observations. Differential scanning calorimetry showed retention of the polyamide crystalline melt with levels of siloxane incorporation of up to 45 weight %. In conclusion, two novel classes of polydimethylsiloxane containing block copolymers have been successfully synthesized, despite the complications created as a result of the polar/non-polar interactions developed between a semi-inorganic polydimethylsiloxane and the hydrocarbon based polyarylene ethers and nylon 6,6. / Ph. D.

L'utilisation des Oxydes de Phosphine Secondaire OPSs en catalyse comme préligand des métaux de transition a connu un regain d'intérêt depuis le début des années 2000. Les complexes organométalliques [M]/OPS ont été utilisés comme catalyseur principalement dans des réactions de couplage ou d'hydrolyse des nitriles. Afin d'étendre le champ d'action des catalyseurs comportant des préligands OPS, nous nous sommes intéressés à ces complexes et avons développé de nouvelles réactions de cycloadditions entre des alcynes terminaux et des dérivés bicycliques [2.2.1]. En utilisant un système catalytique formé in situ à partir d'une source de palladium (II) et d'un oxyde de phosphine secondaire, la réaction de cycloaddition formelle [2+1] entre des esters propargyliques tertiaires et des 8-oxabicyclo[2.2.1]hept-5-ènes conduit à la formation de vinylidènecyclopropanes. Ces produits peuvent subir ultérieurement une réaction d'ouverture/réarrangement du fragment cyclopropyle pour donner des 8-oxabicyclo[3.2.1]oct-6-ènes. Une nouvelle réaction de cycloaddition domino [2+1]/[3+2], catalysée par un complexe [Pt(k2-OAc){(R1R2PO)2H}], entre le norbornadiène et différents éthers ou esters propargyliques a également été développée pour la synthèse de composés tricycliques originaux avec une totale régio- et diastéréosélectivité. / During the past decade, secondary phosphine oxides SPOs have gained increasing interest as preligands of transition metals. Organometallic complexes [M]/SPO have been developed as catalysts in mainly cross-coupling reactions and nitriles hydrolysis. In order to extend the scope of the SPO-based complexes, we have investigated these catalysts and developed new cycloaddition reactions between terminal alkynes and bicyclic[2.2.1] derivatives. A catalytic system prepared in situ from a palladium precursor and a secondary phosphine oxide was found competent to achieve a formal [2+1] cycloaddition between tertiary propargylic carboxylates and 8-oxabicyclo[2.2.1]hept-5-ene derivatives to form vinylidenecyclopropane compounds. Subsequently, these products have been used in a fragmentation sequence in order to prepare 8-oxabicyclo[3.2.1]oct-6-enes.A new domino [2+1]/[3+2] cycloaddition sequence, catalyzed by a [Pt(k2-OAc){(R1R2PO)2H}] complex, between norbornadiene and propargylic esters or ethers have been developed to give original tricyclic compounds with complete regio- and diastereoselectivity.

The correlation between NMR chemical shifts of interstitial atoms and electronic structures of boron- and carbon-centered hexazirconium halide clusters was investigated by density functional theory (DFT) calculation. The influences of bridging halide and terminal ligand variations on electronic structure were examined respectively. Inverse proportionality was found between the chemical shifts and the calculated energy gaps between two Kohn-Sham orbitals of t1u symmetry, which arose from the bonding and antibonding interaction between the zirconium cage bonding orbitals and the interstitial 2p orbitals. Chemical shielding properties of the interstitial atoms were calculated with Gauge Including Atomic Orbital (GIAO) method. Stepwise ligand substitution of terminal chlorides on [(Zr6CCl12)Cl6]4-cluster by tri(n-butyl)-phosphine oxide (Bu3PO) was conducted with the aid of TlPF6. Composition of the reaction mixtures was analyzed by use of both 13C and 31P NMR. A preliminary scheme for synthesis and separation of [(Zr6CCl12)Cl6-x(Bu3PO)x]x-4 (x = 3 ?? 5) mixture based on solubility difference was reevaluated. Three 1,10-phenanthroline based bidentate ligands, namely, 2,9-Bis(diphenyl-phosphinyl)-1,10-phenanthroline, 2,9-Bis(diethoxyphosphoryl)-1,10-phenanthroline, and 2,9-Bis(di-n-butoxyphosphoryl)-1,10-phenantholine, were synthesized for bridge-chelating the hexazirconium clusters. Coordination chemistry of these ligands with the [Zr6BCl12] and [Zr6CCl12] clusters was subject to preliminary investigation.

The correlation between NMR chemical shifts of interstitial atoms and electronic structures of boron- and carbon-centered hexazirconium halide clusters was investigated by density functional theory (DFT) calculation. The influences of bridging halide and terminal ligand variations on electronic structure were examined respectively. Inverse proportionality was found between the chemical shifts and the calculated energy gaps between two Kohn-Sham orbitals of t1u symmetry, which arose from the bonding and antibonding interaction between the zirconium cage bonding orbitals and the interstitial 2p orbitals. Chemical shielding properties of the interstitial atoms were calculated with Gauge Including Atomic Orbital (GIAO) method. Stepwise ligand substitution of terminal chlorides on [(Zr6CCl12)Cl6]4-cluster by tri(n-butyl)-phosphine oxide (Bu3PO) was conducted with the aid of TlPF6. Composition of the reaction mixtures was analyzed by use of both 13C and 31P NMR. A preliminary scheme for synthesis and separation of [(Zr6CCl12)Cl6-x(Bu3PO)x]x-4 (x = 3 ?? 5) mixture based on solubility difference was reevaluated. Three 1,10-phenanthroline based bidentate ligands, namely, 2,9-Bis(diphenyl-phosphinyl)-1,10-phenanthroline, 2,9-Bis(diethoxyphosphoryl)-1,10-phenanthroline, and 2,9-Bis(di-n-butoxyphosphoryl)-1,10-phenantholine, were synthesized for bridge-chelating the hexazirconium clusters. Coordination chemistry of these ligands with the [Zr6BCl12] and [Zr6CCl12] clusters was subject to preliminary investigation.