This dissertation focuses on the fundamental understanding of the proton transfer process and translating the knowledge into design/development of new organic materials for efficient non-aqueous proton transport. For example, what controls the shuttling of a proton between two basic sites? a) Distance between two groups? or b) the basicity? c) What is the impact of protonation on molecular conformation when the basic sites are attached to rigid scaffolds? For this purpose, we developed several tunable proton sponges and studied proton transfer in these scaffolds theoretically as well as experimentally. Next we moved our attention to understand long-range proton conduction or proton transport. We introduced liquid crystalline (LC) proton conductor based on triphenylene molecule and established that activation energy barrier for proton transport is lower in the LC phase compared to the crystalline phase. Furthermore, we investigated the impact of several critical factors: the choice of the proton transferring groups, mobility of the charge carriers, intrinsic vs. extrinsic charge carrier concentrations and the molecular architectures on long-range proton transport. The outcome of this research will lead to a deeper understanding of non-aqueous proton transfer process and aid the design of next generation proton exchange membrane (PEM) for fuel cell.

Room temperature ionic liquids (ILs) are a unique class of solvents which are characterized by non-volatility, non-flammability, electrochemical stability and high ionic conductivity. These properties are highly desirable for ion-conducting electrolytes, and much work has focused on realizing their application in practical devices. In addition, hydrophilic and ionophilic polymers are generally miscible with ILs. The miscibility of ILs with ion-coordinating polymers makes ILs effective plasticizers for gel polymer electrolytes. Due to their unique properties, ILs present a means to realize the next generation of energy storage technology. In this dissertation, the fundamental interactions between poly(ethylene oxide) (PEO) and a variety of room temperature ILs were investigated. ILs with acidic protons were demonstrated to form a stronger interaction with PEO than ILs without such protons, suggesting that hydrogen bonding plays a dominant role for PEO miscibility with ILs. The hydrogen bonding interaction is selective for the PEO block of a PEO-b-PPO-b-PEO block copolymer (BCP). Therefore, blending these copolymers with the strongly interacting IL 1-butyl-3-methylimidazolium hexafluorophosphate ([BMI][PF6]) induced microphase separation into a well-ordered structure, whereas the neat copolymer is phase mixed. At sufficient quantities, the interaction between [BMI][PF6] and PEO suppresses PEO crystallinity entirely. In addition, the induced microphase separation may prove beneficial for ion conduction. Therefore, microphase separated copolymer/IL blends were investigated as potential gel polymer electrolytes. Cross-linkable block copolymers which microphase separate when blended with [BMI][PF6] were synthesized by modifying PPO-b-PEO-b-PPO copolymers with methacrylate end-groups. Cross-linking these copolymers while swollen with an IL generates ion gels with high ionic conductivities. The copolymer/IL blends vary from a well-ordered, strongly microphase separated state to a poorly ordered and weakly microphase separated state, depending upon the molecular weight. Stronger microphase separation results in higher mechanical strength upon cross-linking. However, this does not greatly affect ion conductivity. Nor is conductivity affected by forming gels from cross-linked PEO homopolymers when compared to BCPs. It was found that BCPs can be beneficial in producing gel electrolytes by allowing sequestration of phase selective cross-linkers away from the conducting block. Cross-linker molecules that are selective for the PPO blocks can be used to increase the mechanical strength of the gels with only a small effect on the conductivity. When cross-linkers that partition to the mixed PEO/IL block are used, the conductivity decreases by nearly a factor of 2. These studies show how ILs interact with PEO and how gel polymer electrolytes can be constructed with the IL [BMI][PF6]. While BCPs cannot directly be used to increase ion conductivity, they do allow for greater mechanical strength without sacrificing conductivity. This suggests many new approaches that may be used to simultaneously achieve high ionic conductivity and mechanical strength in solid and gel polymer electrolytes.

This thesis is divided into two research initiatives: The fabrication and study of bulk, co-continuous, cellulosic-polymer composites with the aid of supercritical CO2 (SC CO2); and the study of poly(vinyl alcohol) (PVOH) modification and surface activity in ionic liquids. The first part of this thesis utilizes the tunable solubility, gas-like diffusivity, and omniphilic wettability of SC CO2 to incorporate and subsequently polymerize silicone and poly(enemer) prepolymer mixtures throughout various cellulosic substrates. Chapters two and three investigate the mechanical properties of these composites and demonstrate that nearly every resulting composite demonstrates an improved flexural modulus and energy release rate upon splitting. Fire resistance of these composites was also investigated and indicates that the heat release rate, total heat released, and char yield were significantly improved upon for all silicone composites compared to the untreated cellulosic material. Chapter four looks specifically at aspen-silicone composites for thermo-oxidative studies under applied loads in order to study the effect of silicone incorporation on the failure kinetics of aspen. The aspen-silicone composites tested under these conditions demonstrated significantly longer lifetimes under the same loading and heating conditions compared with untreated aspen. The second part of this thesis focuses on studying ionic liquids as potentially useful solvents and reaction media for poly(vinyl alcohol). Two ionic liquids (1-Butyl-3-methylimidizolium chloride and tributylethylphosphonium diethylphosphate) were found to readily dissolve PVOH. More importantly, we have demonstrated that these solvents can be used as inert reaction media for PVOH modification. Both ionic liquids were found to facilitate the quantitative esterification of PVOH, while only the phosphonium ionic liquid supports the quantitative urethanation of the polymer. In an attempt to tune the surface properties of ionic liquid/polymer solutions, PVOH was also partially esterified with low surface energy substituents. Both surface tension and surface composition of the ionic liquid/polymer solutions can be manipulated by the stoichiometric addition of low surface energy acid chlorides. This work on the modification of PVOH can be directly applied to the modification of polysaccharides such as cellulose which could have important implications from a sustainability and energy standpoint.

Synthesis and magneto-structural characterization of hydrogen bonded organic nitronylnitroxide and verdazyl radicals were done. 35diMeO–4OHPhNN displayed 1D antiferromagnetic interactions attributed to the chain contacts between radical NO groups. Benzimidazole-based verdazyl radicals 2BImverd, and 5BImverd did not give diffraction quality crystals and were only characterized by EPR. The analogues 2BImisoverd and 5BImisoverd both gave x-ray diffraction quality single crystals that displayed formation of hydrogen bonded chains through the imidazole moieties. The magnetic susceptibility results indicated the presence of weak 1D AFM interactions for both radicals. The weakness of interactions was attributed to bulky isopropyl groups pushing the molecules apart and decreasing spin orbital overlap. A series of organic radical solid solutions (alloys) were made using BImNN and its fluorinated analogue F4BImNN. (F4BImNN)x(BImNN) (1−x) with x < 0.8 gave orthorhombic unit cells, while x > 0.88 gave monoclinic unit cells. (F4BImNN) (x)(BImNN)(1−x) (x = 0.1, 0.17, 0.25, 0.5, 0.75, 0.83, 0.9) displayed ferromagnetic interactions with J/k = (+)14–22 K, mainly controlled by hydrogen-bonded assembly of the radicals. Magnetic analysis over 0.4–300 K showed ordering behavior for all of these materials. The ordering temperatures of the orthorhombic samples increased linearly as (1−x) increased from 0.25 to 1.00. The variation was attributed to increased inter-chain distance as more F4BImNN was added into the orthorhombic lattice. The monoclinic samples were not part of the same trend, which was attributed to a change in the inter-chain arrangement. This was the very first study giving such complete magnetostructural detail linking ordering behavior to specific crystallographic features and intermolecular contacts. The magnetic behavior of F4BImNN was investigated at increased external pressures. The crystallographic c-axis (along which hydrogen bonds form) was compressed by 3% at 10 kbar and by 4% at 17.8 kbar. The overall lattice volume contracted by 12% from ambient pressure to 17.8 kbar. The magnetic susceptibility measured over 1.8–300 K showed an increase in ferromagnetic exchange interactions as pressure increased. The increase in exchange strength was attributed to pressure-increased overlap of spin orbitals in the hydrogen-bonded chains, which favored 1D ferromagnetic interaction. Electron paramagnetic resonance experiments on a single crystal of F4BImNN were also performed. The variation in g-value as a function of the crystal's position with respect to the applied magnetic field was investigated. The angular dependence of g was more pronounced at temperatures below 30 K. Pyrrole-based nitronylnitroxide radicals mNNPP, N–PN and 35NNPP were studied. mNNPP displayed formation of 1D chains with weak intra-chain FM interactions, N–PN gave 1D AFM interactions, and 35NNPP showed intramolecular FM and intermolecular AFM interactions.

A series of para-linked aromatic polyamides synthesized with the aim of making optically uniaxial, transparent films and fibers for optical applications, are found to have anomalous properties. Stretched films of these polyamides are highly birefringent and non-crystalline at the same time. These rod-like polyamides do not form lyotropic solutions and are soluble in common solvents like THF, unlike other rod-like polymers. With the goal of understanding this behavior from a molecular standpoint we have quantitatively characterized the geometric, optical and hydrodynamic properties of one of these polyamides. With angle light scattering measurements on polyamide in THF were used in conjunction with electric birefringence measurements to determine the weight average molecular weight, M$\sb{\rm w}$, the root mean square z-averaged radius of gyration, R$\sb{\rm gz}$, the apparent second virial coefficient, A$\sb{\rm 2app}$ and the monomer molecular anisotropy ratio $\varepsilon$. The polydispersity correction was applied theoretically by assuming the most probable distribution. Hydrodynamic and optical properties were determined with viscometry and differential refractometry respectively. The aromatic polyamide studied can be satisfactorily modeled as a Kratky-Porod wormlike chain with a persistence length of 220 $\pm$ 50 A and a monomer optical anisotropy ratio of 2.3 $\pm$ 0.3. The excluded volume effect is found to be negligible in THF at 25$\sp\circ$C. The small axial ratio of 30 may be partly responsible for the non-lyotropic behavior. The refractive index of 1.67 is in good agreement with that of similar polyamides. The repeat unit has a high optical anisotropy leading to highly birefringent films. It is also conclusively established that there is no aggregation due to H-bonding in the absence of moisture. The light scattering theory of Nagai and the hydrodynamic theory adopted for semiflexible chains is found to hold very well for the polyamide studied. Based on the agreement between experiment and theory we infer that the molecular weight distribution is of the most probable type. Our depolarized light scattering data indicate that the straight line behavior observed in Zimm plots even for $\rm R\sb{g}\sp2q\sp2>1$, upto $\rm R\sb{g}\sp2q\sp2$ of 3.5 is due to the combined effect of polydispersity, large size and optical anisotropy of the molecule.

Various important aspects of discontinuous fiber composites have been studied in detail both experimentally and theoretically through a model composite containing polydiacetylene (PDA) single crystal as the reinforcement fiber and epoxy resin as the matrix. The aspects encompass varying degrees of fiber behavior as well as fiber/matrix interaction, such as compressive behavior of the reinforcement fiber, geometry effects of the fiber on the stress distribution along the fiber, fiber orientation, residual thermal stress, and the role of fiber/matrix interfacial properties on the performance of composites. The compressive failure mode of the PDA fiber used in this study is the formation of readily observable kink bands. The critical compressive strain of the fiber was found to be 0.3%. By monitoring the behavior of the C$\equiv$C bond frequency in PDA in response to applied compressive loads, the stress along the fiber can be determined leading to the establishment of a calibration curve describing the relationship between the frequency change of the bond and the compressive strain due to residual thermal stress caused by differences in thermal expansion between fiber and matrix. This thermal stress will cause fiber compressive failure if the critical compressive strain is achieved. A quantitative analysis of the data reveals that no slippage occurs at the fiber/matrix interface during the build-up of thermal stress. The geometry of the fiber was found to play a significant role. Both experimental and finite element analysis demonstrate the advantage of tapered end fiber over the ordinary blunt end fiber, i.e. fiber with a uniform diameter. The experimental apparatus constructed in this study allows the measurement of tensile strain distribution of the fibers orientated at any angle with respect to the draw direction to be determined accurately. For a thin layer coating of the fiber, it was found that the tensile strain distribution along the fiber was unaffected, and so by extension neither would the modulus of a composite in fiber axial direction be affected. This observation indicates that for most composite systems perfect bonding is easily formed at the fiber/matrix interface as far as tensile stress transfer is concerned. (Abstract shortened with permission of author.)

This dissertation presents a new technique for determining the residual stresses and material properties of polyimide coatings. The primary materials studied are polyimides, pyromellitic dianhydride-oxydianiline (PMDA-ODA) and poly (N,N$\sp\prime$(phenylene)-3,3$\sp\prime4,4\sp\prime$-biphenyl tetracarboxylic diimide) (BPDA-PDA). The determination of the internal stresses which develop during processing in these coatings is critical for reliability prediction and material selection for the microelectronics industry. For any given coating on a rigid substrate, the shear and normal tractions between the two materials goes to zero away from the edges. A portion of the substrate can therefore be removed leaving a simply supported membrane (coating) with its original state of stress intact. Classical vibration theory states that the square of the resonant frequency of a membrane is proportional to its biaxial stress. Real-time holographic interferometry is used to identify the resonant modes of vibration. It is also shown that using this technique the orthotropic axes of polymer films can be identified, thus simplifying the determination of all nine orthotropic elasticity coefficients.

Polymer surface modification can be accomplished by several techniques including chemical reaction and adsorption. In Chapter I, a simple and versatile technique to introduce carboxylic acid functionality to the surfaces of three fluoropolymer film samples is described. In Chapter II, the adsorption of neutral poly(scL-lysine) (PLL) from solution to the water-fluoropolymer interface is described. Chapter III combines the methods of surface modification described in Chapters I and II and discusses the adsorption of charged PLL to a carboxylic acid-functionalized fluoropolymer film surface. The hydrophobic interaction as a driving force for adsorption is further studied in Chapter IV where the synthesis and adsorption of poly(ethylene oxide) (PEO) and its derivatives are discussed. The syntheses of carboxylic acid-functionalized fluoropolymer films rely upon a two step mechanism where unsaturation, introduced in the first step, is oxidatively removed in the second step; one acidic group per twelve to sixteen repeat units was introduced to the surface. Contact angles ($\theta\sb{\rm A}$/$\theta\sb{\rm R}$) of the acid-functionalized fluoropolymer films decrease with increasing pH: PVF$\sb2$-CO$\sb2$H (77$\sp\circ$/39$\sp\circ$ decreases to 68$\sp\circ$/25$\sp\circ$); PCTFE-CO$\sb2$H (93$\sp\circ$/55$\sp\circ$ decreases to 93$\sp\circ$/43$\sp\circ$); and FEP-CO$\sb2$H (101$\sp\circ$/78$\sp\circ$ decreases to 97$\sp\circ$/61$\sp\circ$). The adsorption of poly(scL-lysine) (PLL) to the water-FEP interface was controlled by pH of the aqueous solution and PLL solution conformation. Only neutral, $\alpha$-helical PLL adsorbed to FEP (FEP-PLL). The adsorption of PLL to carboxylic acid-functionalized FEP, FEP-CO$\sb2$H, was controlled by an electrostatic interaction; both a hydrogen bonding interaction between FEP-carboxylic acid and PLL backbone and an ionic interaction between FEP-carboxylate and PLL-ammonium enhanced adsorption. Both FEP-PLL (80$\sp\circ$/16$\sp\circ$) and FEP-CO$\sb2$H-PLL (78$\sp\circ$/29$\sp\circ$) are more hydrophilic than FEP. FEP-PLL-$\varepsilon$-amine reacts with 3,5-dinitrobenzoyl chloride in 65% yield whereas FEP-CO$\sb2$H-PLL-$\varepsilon$-amine reacts in 100% yield. Adsorption of PLL to FEP and FEP-CO$\sb2$H improves the peel strength of adhesive joints prepared with these substrates and the adhesion and growth of biological cells on these film samples. PEO (5,000 to 50,000 g/mole and polydispersity indices of 1.07 to 1.17) was synthesized by anionic ring opening polymerization of ethylene oxide in THF with triethylene glycol monomethyl ether potassium initiation. PEO was end-capped (PEO-R) by reaction with a (perfluoro)alkyl acid chloride in THF with pyridine catalysis. A polar interaction between substrate and segment controlled adsorption at the fluoropolymer-water interface; PEO adsorbed preferentially to PVF$\sb2$ over PCTFE and FEP. Both PEO and PEO-R adsorbed to the polystyrene latex-water interface; the latter formed a thicker adsorbed layer. PEO-R showed increased surface activity over PEO at the air-water interface; PEO-perfluorodecanoate decreased the surface tension of water to 35 dyn/cm.

The compressive failure of high-modulus polymer fibers, such as poly(p-phenylene terephthalamide) (PPTA) and poly(p-phenylene benzobisthiazole) (PBZT), occurs at stresses an order of magnitude smaller than their tensile failure. A literature review is presented which covers the numerous theories and models for the compressive strength and failure of these fibers as well as of uniaxial composites, which are structurally similar and fail in an analogous fashion. It is pointed out that the smallest shear modulus of any material is a fundamental upper bound to its compressive strength. Physical combination of high-modulus polymers with rigid inorganic materials by impregnation or by deposition of coatings are presently the most promising routes to improved compressive strength and are the research topics presented in this dissertation. PPTA fibers, obtained by spinning from nematic solution, have been impregnated with up to 20 wt-% of a waterborne, highly crosslinkable melamine-formaldehyde resin and with approximately 5 wt-% of sodium silicate from a colloidal aqueous solution. PBZT fibers have also been impregnated with approximately 5 wt-% of sodium silicate. PPTA fibers, obtained by spinning from isotropic solution, have been impregnated with up to 40 wt-% of sodium silicate. None of the impregnations has led to improved compressive strength or other mechanical properties. Kevlar$\sp\circler$ 49 PPTA fibers and heat-treated PBZT fibers have been surface modified with siloxane and silicate functionalities in order to make fibers wettable by aqueous solutions of sodium silicate and to provide good adhesion to silicate coatings. The surfaces of as-received and modified fibers have been characterized by X-ray photoelectron spectroscopy. PBZT and PPTA fibers showed little or no decrease of their tensile properties as a consequence of the surface modification. Glass coatings have been applied to single filaments by dip-coating in aqueous sodium silicate solution followed by drying. Coated PPTA and PBZT fibers with shear moduli as high as 5 GPa have been prepared. The compressive strain at failure of PPTA filaments coated with a 0.5 $\mu$m thick silicate coating was raised to 0.6%, compared to 0.4% for uncoated filaments. These compressive failure strains correspond to compressive strengths of approximately 500 and 400 MPa, respectively.

Trace impurity determinations in volatile, pyrophoric organometallic materials is complicated owing to its chemical nature. Furthermore, trends toward high semiconductor circuit density demand that impurity determinations are performed at increasingly low levels. Volatility of the impurities is also desired as it plays a significant role in impurity incorporation in semiconductor products. Determination of both volatile and nonvolatile impurities in semiconductor-grade organometallic reagent materials has been accomplished using electrothermal vaporization - inductively coupled plasma spectrometry. Solid or liquid materials can be dispensed directly onto a graphite microboat, and application of an appropriate time-temperature ramp allows separation of impurities based on volatility. Temporal separation allows quantitative capabilities on both volatile and nonvolatile signals in a single ETV run. Calibration efforts for volatile impurities have been compared with results from exponential dilution and direct vapor sampling techniques. Nonvolatile impurity determinations can be reasonably performed with aqueous external standard calibration. Inductively coupled plasma-mass spectrometry provides an alternate and more sensitive, multielement detection method. Several spectroscopic and non-spectroscopic difficulties with volatile impurity detection remain. Nonetheless, qualitative and semi-quantitative ($<$50% RSD) determination of most impurities may be performed in a single ETV run.