Image Theses and Dissertations A temperature-dependent model for an AlInAs/GaInAs heterojunction bipolar transistor View Item
Image Theses and Dissertations An electrochemical capacitance-voltage technique for the determination of pseudomorphic high electron mobility transistor material parameters View Item
Image Theses and Dissertations Quantitative scanning microwave microscopy of a biological cell The electromagnetic properties of a live biological system are extremely important to many medical applications. While information about electromagnetic properties of tissues are available in the literature, little or no data are available for a single cell or subcellular structures. Microwave biological/cell detection has been demonstrated to be useful and promising in many medical applications due to its internal properties such as non-invasive, fast and label-free. View Item
Image Theses and Dissertations Role of reactive surfactants in emulsion polymerization. The reactive surfactant HITENOL BC20 (polyoxyethylene alkylphenyl ether ammonium sulfate) with 20 units of ethylene oxide (EO) was used in emulsion polymerizations of styrene and copolymerization of styrene and n-butyl acrylate. Surfactant characterization shows that surfactant BC20 can not be self-polymerized. View Item
Image Theses and Dissertations The effect of cross-linking on latex film formation. The effect of the crosslinker chain lengths in the copolymerization reaction with n-BMA and the formation of the resulting latex films was investigated. Three crosslinkers; ethylene glycol dimethacrylate (EGDMA-198 g/mol), Aliphatic Urethane Acrylate (AUA-3728 g/mol) and a novel Macromonomer Crosslinker (Mac-3480 g/mol) were compared. Copolymerization was achieved via a miniemulsion process. View Item
Image Theses and Dissertations Grafting reactions in the emulsion polymerization of vinyl acetate using poly(vinyl alcohol) as emulsifier. The role of grafting in the particle nucleation mechanism during the emulsion polymerization of vinyl acetate (VAc) using partially hydrolyzed poly(vinyl alcohol) (PVA) as emulsifier and potassium persulfate as initiator was investigated. The polymerizations were carried out in batch using a low solids (10%) recipe. 1H-NMR, 13C-NMR and HPLC techniques were used to characterize the PVA with respect to its acetyl sequence distribution (degree of blockiness). Temperature dependent 1H-NMR and DSV coupled with DLS was used to elucidate the aqueous phase conformation of the pVAs. View Item
Image Theses and Dissertations Fundamentals of emulsion of polymerization studied by reaction calorimetry. Various fundamental aspects of the kinetics of emulsion polymerization were studied using reaction calorimetry to measure the actual kinetic profile. The major part of this investigation was carried out with styrene as the model monomer. The bench mark for comparison of results was a well characterized reaction reported in the literature for the system Styrene/sodium lauryl sulfate/potassium persulfate from which Stage II was defined as a reaction interval with increasing heat of reaction and increasing number of particles after the micelles disappearance. View Item
Image Theses and Dissertations Study of the incorporation of alkoxysilane monomers into model latex systems. A miniemulsion copolymerization technique was applied to incorporate vinylalkoxysilanes into acrylate latex systems by an one-step batch polymerization. The use of the miniemulsion approach yields lower coagulum amounts at high silane feed contents compared to the conventional emulsion polymerization. View Item
Image Theses and Dissertations Preparation of urethane/acrylic hybrid miniemulsion nanoparticles. Nanosized polyurethane (PU)/poly(n-butyl methacrylate) (PBMA) hybrid latex particles (∼50 nm) with various compositions were successfully prepared using a redox-initiated miniemulsion polymerization process. View Item
Image Theses and Dissertations Poly(vinyl alcohol) stabilization of acrylic emulsion polymers using the miniemulsion approach. Miniemulsion approach was employed to obtain stable acrylic latexes of n-butyl acrylate and methyl methacrylate (50/50 wt%) stabilized with poly(vinyl alcohol) (PVA) and to enhance the grafting reaction between PVA and acrylic monomers at the water/droplet interface. The stability of miniemulsions were studied in terms of the type and concentration of' the stabilizer, and the PVA partitioning were determined as a function of the PVA concentration. View Item
Image Theses and Dissertations Hybrid composite latexes. A direct miniemulsification approach followed by subsequent polymerization has been utilized to synthesize a series of hybrid composite latexes. View Item
Image Theses and Dissertations The role of mixed anionic-nonionic systems of surfactants in the emulsion polymerization of styrene. The kinetics of the emulsion polymerization of styrene in the presence of mixtures of SLS and Triton X-405 were studied under various conditions.;The competitive adsorption of SLS and Triton X-405 on polystyrene particles was studied. At low surfactant content, Triton X-405 adsorbed preferentially on the surface of the PS particles. In some cases, it was able to displace some of the SLS from the surface. View Item
Image Theses and Dissertations Living/controlled free radical miniemulsion polymerization of styrene. TEMPO-controlled living free radical polymerizations were studied in miniemulsion systems in this research. TTOPS was synthesized, and used as a macro-initiator. It was found that the polymerization rate is low. Molecular weight increases linearly with increasing conversion, and is narrowly distributed. The effect of TTOPS concentration was studied and it was found that the polymerization rate was independent of the TTOPS concentration. View Item
Image Theses and Dissertations Controlled radical miniemulsion polymerization via the RAFT process. Two reversible addition-fragmentation chain transfer (RAFT) agents, cumyl dithiobenzoate (CDB) and benzyl dithiobenzoate (BDB) were prepared in the lab and were found suitable for the RAFT miniemulsion polymerization due to their low water solubility and the strong phase partitioning towards the monomer oil phase.;The RAFT process in the CDB-mediated conventional emulsion polymerization was found to be unsuccessful, showing loss of molecular weight control and latex stability as a result of insufficient diffusion of the RAFT agent through the aqueous phase from the monomer droplets to the m View Item
Image Theses and Dissertations Conventional emulsion and miniemulsion homopolymerization and copolymerization of vinyl acetate and vinyl 2-ethylhexanoate monomers. For monomers possessing significantly low water solubility (V2EH), miniemulsion polymerization can substantially enhance the reaction kinetics compared to conventional emulsion systems. While the monomer droplets in a conventional emulsion only serve as reservoirs supplying monomer, diffusional restrictions of the monomer to get to the site of nucleation and the growing particles effectively slows the reaction. View Item
Image Theses and Dissertations Kinetics and mechanism of dispersion polymerization. Dispersion polymerization is an attractive method to prepare micron-size polymer particles with narrow size distribution in one single step. The present research systematically studied the kinetics of dispersion polymerization of methyl methacrylate (MMA) and n-butyl acrylate ( n-BuA). Effects of reaction conditions on the kinetics were investigated using a reaction calorimeter (Mettler RC1). View Item
Image Theses and Dissertations Nanosize latex particles via miniemulsion polymerization. The mechanisms of miniemulsion formation, stabilization, and polymerization were studied both experimentally and theoretically. The subdivision of miniemulsion droplets was investigated as a function of homogenization energy. The stabilization of droplets against Ostwald ripening has been explained on a thermodynamic basis. Miniemulsions and their corresponding latexes were synthesized and characterized for particle size and surface coverage by surfactant titration, as well as polymerization rate using calorimetry. View Item
Image Theses and Dissertations Emulsion polymerization of styrene using a reactive surfactant. Emulsion polymerizations of styrene using the reactive surfactant, sodium dodecyl allyl sulfosuccinate, TREM LF-40, its hydrogenated derivative, H-TREM, and its polymeric counterpart, poly(TREM), were studied. The critical micelle concentrations (cmc), adsorption isotherms and the presence of double bonds were determined for the three surfactants. The kinetics of emulsion polymerizations using TREM LF-40 were found to be unusual with varying TREM LF-40 concentrations ([E]) in that the reaction rate Rp was not found to be directly proportional to the number of particles, Np (Rp ∝ Np0.67). View Item
Image Theses and Dissertations Encapsulation of inorganic particles via miniemulsification and film formation of resulting composite latex particles. The application of the miniemulsification process to the encapsulation of TiO2 particles in polymer/copolymer particles was investigated. Dispersion studies have shown that Solsperse 32,000 was selected as the best stabilizer for TiO2 particles. Then, the encapsulation of 3 wt% TiO2 particles (hydrophilic) stabilized with 1 wt% Solsperse 32,000 in PS, PBA and 50:50 wt% a styrene/n-butyl acrylate (St/BA) copolymer via miniemulsion polymerization was investigated. View Item
Image Theses and Dissertations Encapsulation of inorganic particles via miniemulsion polymerization. The application of the miniemulsion polymerization approach to the encapsulation of size titanium dioxide (TiO2) particles in polystyrene latex particles was investigated. Successful encapsulations were only achieved when the TiO2 particles, either hydrophilic or hydrophobic, were adequately dispersed in the styrene monomer prior to formation and polymerization of the miniemulsions. View Item
Image Theses and Dissertations Effects of injection current density and active layer doping and thickness on the spectral emission properties of high-speed 1.3 um InGaAsP surface emitting light emitting diodes View Item
Image Theses and Dissertations The effect of N layer doping level on the forward voltage of AlGaAs double-heterostructure light emitting diodes View Item
Image Theses and Dissertations Dielectric Spectroscopy of Biological Samples For the first time, the impedance spectrum of live Jurkat T-lymphocytes human cells was characterized in a single sweep spanning six decades of frequency from 9 kHz to 9 GHz. The ultrawide bandwidth bridged the traditional impedance spectroscopy at kilohertz to megahertz frequencies with the recently developed microwave dielectric spectroscopy, which can probe the cell interior without being hindered by the cell membrane. View Item
Image Theses and Dissertations Development of a 1[mu]m GaAs metal-semiconductor field effect transistor fabrication process View Item