The flexible substrate was fabricated by BaTi4O9 mixed with O-Cresol Novolac Epoxy, polyether imide or surface active agents. The electrical and physical characteristic measured had been finished. The dielectric property influence of substrate was changed from percentage of BaTi4O9. The dielectric constant model was used by Jayasundere and Smith equation (J. S. eq.) and Lichtenecker equation (L. eq.) The study of crystalline grain, orientation and phase transfer temperature was used by SEM, XRD, and DSC, respectively. The dielectric constant and dielectric loss tangent of the composite was measured using an HP4294A impedance analyzer. The TM mode calculated by resonate frequency of the composite was measured using an HP4156C network analyzer. The dielectric constant was obtained to TM mode at high frequency. The result was showed that dielectric constant at low frequency of BaTi4O9, OCN Epoxy and PEI are 57, 5.8 and 3.65, respectively. OCN Epoxy is better than PEI of electrical characteristic. However, OCN Epoxy is not flexible. For this reason, the PEI was focused on electrical property at high frequency. The BaTi4O9 exhibited a dielectric constant of 39 at frequency during 3~10 GHz. The dielectric constant was measured of 10 at frequency during 2~16 GHz with 70 wt% PEI composite. The dielectric constant is higher than FR-4 substrate to 6.4 of the composite. The low dielectric constant is obtaining to reduce stuffing.

Polypyrroles containing polyether pseudocages (PI, PII, PIII) have been synthesized via chemical oxidation of 1,5-bis(1,1-pyrrole)-3-oxabutane (MI), 1,8- bis(1,1-pyrrole)-3,6-dioxahexane (MII), and 1,11-bis(1,1-pyrrole)- 3,6,9-trioxaundecane (MIII) using anhydrous FeCl3 in CHCl3. Because as obtained polymer resins did not give any response toward any cations, they were reduced (undoped) using chemical reducing agents. Tetrabutylammonium hydroxide (TBAOH) was found to be more effective in undoping to obtain more reproducible and reusable polymer resins. It was investigated whether the undoped polymer resins were used for the extraction of rare earth metal ions from the aqueous medium. Among them, only PIII resin can extract La(III), Eu(III) and Yb(III) from their aqueous solutions and can be employed for the preconcentration of these metal ions. For batch extraction of La(III), Eu(III) and Yb(III) at neutral pH values, percent recoveries of 98.0, 90.7 and 87.3, respectively, has been obtained by using Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES) technique. The sorption capacity is found as 1.3 mg of La(III) per gram of PIII resin. The PIII resin could be reused at least five times without significant change in its sorption capacity. PIII has also been synthesized via electrochemical method to be used in the preparation of Surface Enhanced Raman Scattering (SERS) active substrate. PIII has been polymerized on Indium Tin Oxide (ITO) glass by using constant potential electrolysis. In an electrolyte solution containing 0.05M tetrabutylammonium perchlorate (TBAP), 1.2 V vs. Ag wire (oxidation potential of MIII) was applied for coating and then silver particles were deposited on the surface of PIII coated ITO electrode by reducing Ag(I) in monomer free electrolyte solution electrochemically. As an alternative, another SERS substrate was prepared electrochemically by depositing silver particles directly on ITO glass. The performances of prepared ITO-PIII-Ag and ITO-Ag SERS substrates were evaluated with dilute solutions of brilliant cresyl blue (BCB), crystal violet (CV), para amino benzoic acid (PABA), nicotine and nicotinic acid.

NONE.

This thesis provides investigation into the interaction between quartz lamp emitters and polyether ether ketone (PEEK) powder. Calculations and experiments concerning the conductivity and emissivity of the powder at various temperatures are performed. The thermal profile of the emitter on a flat powder bed is captured using thermal imaging. The effect of exposing a pile of powder to the emitter and the subsequent thermal gradient through the pile is measured and analyzed. Based on these results, ramifications for the application of these emitters to selective laser sintering (SLS) machines for processing high temperature polymers such as PEEK are discussed. / text

The chemical structure of polyether amines (PEA), mainly electron donating multiple oxygen and nitrogen atoms as well as active hydrogen atoms, make such compounds actively participating in the formation of hydrogen bonds with surrounding molecules. Hydrophobic polypropylene glycol functionality gives PEA's properties of multi-headed surfactants having hydrophilic amine groups. These groups have a strong affinity for water molecules, ice and hydrate crystals. Such PEA compounds have been known for several years. However, the hydrate inhibition properties of PEA’s were only discovered about twelve years ago. The first discovery stimulated more research in laboratories and led to practical applications for hydrate inhibition in gas fields. An interesting property of PEAs is their synergistic effect on hydrate inhibition when applied concurrently with polymeric kinetic hydrate inhibitors (KHI) or thermodynamic inhibitors (THI). The combination inhibitors are better inhibitors than a single component one. Quaternized polyether diamines are efficient antiagglomerant (AA) hydrate inhibitors while different derivatization can produce dual functionality compounds, i.e. corrosion inhibitors/gas hydrate inhibitors (CI/GHI). With all of this versatility, PEAs found application for hydrate inhibition in oil and gas fields onshore and offshore in production, flowlines and completion. The PEAs have an excellent record in protecting gas-producing wells from plugging with hydrates. (Final corrected copy of ICGH paper 5347)

High resolution solid state 1H NMR is used to investigate proton mobility of Nafion, Sulfonated Polyether Ether Ketones(S-PEEK) and their composites, which provides better understanding of their proton conductivities. Proton exchange between sulfonic acid groups and water was observed in these materials. The proton mobility is dependent on both the temperature and the water content. Variable temperature experiments were used to determine the activation energy for proton transportation which generally increases with decrease in hydration level. The preparation of Nafion/SiO2 composites can cause large difference in proton diffusion coefficients and proton conductivities in dried states. This indicates that the amount of dopants needs to be optimized to minimize the blocking of proton diffusion pathways by dopant particles. Detailed information on the control of surface hydroxyl groups in Nafion/SiO2 is obtained through the combination of 29Si and 1H NMR. Although hydrated Nafion/ZrP composites show reduced proton activation energy, they present lower proton conductivity at 35°C than unmodified Nafion. For composites dried at 160°C, both the conversion of monohydrogen phosphate into pyrophosphate and the protonation of monohydrogen phosphate have been observed, which could be one of reasons for the decreased proton conductivity after rehydration. Under high humidification, a single or multiple sulfonic acid proton environments was observed in S-PEEKs, which explains the small proton conductivity difference between some of S-PEEKs. However, the observed conductivity difference for S-PEEKs cast from different solvents was attributed to distinct mobilities of polymer chains. In the crosslinked S-PEEK, not all the crosslinkers of ethylene glycol are fully crosslinked. Proton exchange between residual sulfonic acid and hydroxyls of the crosslinker was observed, which is the primary reason that the crosslinked S-PEEK, with very low residual degree of sulfonation (13 %), still shows proton conductivity comparable to those of S-PEEKs. / Thesis / Doctor of Philosophy (PhD)

<p> High-end optical grade applications would benefit greatly from the unique mechanical and chemical properties of titanium alloys. However, the standard process of manufacturing optical components has not been explored in depth for titanium alloys. </p> <p> Thus the focus of this work was to extend ultra precision machining technology to produce optical grade surfaces on titanium components. An optical surface is characterized by surface roughness less than 10nm R_rms which are typically produced with single crystal diamond tools having a cutting edge radius on the order of 50-100 nm. A cutting speed of 60m/min, feed rate of 1.5 µm/ rev and depth of cut of 2 µm, was identified to achieve the surface finish target, but the practical limitation of this process was still with tool life and the rapid degradation of surface finish over time. </p> <p> This was attributed to the adhesion of titanium material on the tool that resulted in material pull out and side-flow during machining. Results obtained from the characterization of the tool and workpiece led to the identification of graphitization as the initial wear mechanism. As the cutting edge rounds-off due to graphitization, the rate of adhesion of the workpiece material onto the tool increased. For this reason solutions were explored that would reduce the graphitization process and delay the onset of intense adhension. </p> <p> Thus a coating technology involving Perfluoro Polyether (PFPE) was chosen. Tribometer analysis under a load of 500N and temperature of 450ºC between the uncoated and PFPE coated diamond tools and titanium pins showed a remarkable reduction in COF from 0.275 to 0.05. A significant enhancement in tool life and surface quality was also achieved in single point diamond turning (SPDT) of titanium alloys using PFPE coated diamond tools. Tool life was based on an assessment of the cutting length achieved before the surface roughness exceeded the targeted value of 10 nm R_rms and it improved from 1.25 km and 5.1 km with PFPE coated tools. </p> / Thesis / Doctor of Philosophy (PhD)

No description available.

The increase in microbial resistance to antibiotics underscores the need for novel antibacterial surfaces, particularly for silicone-based implants, because the hydrophobicity of silicones has been linked to undesirable microbial adhesion and biofilm formation. Unfortunately, current strategies for mitigation, such as pretreatment of surfaces with antiseptics/antibiotics, are not consistently effective. In fact, they can facilitate the prevalence of resistant pathogens by exposing bacteria to sublethal concentrations of biocides. Therefore, scientific interest has shifted to preventing initial adhesion (prior to surface colonization) by using surfactants as surface modifiers. Accordingly, Chapter 2 studied the bioactivity of ACR-008 UP (an acrylic-terminated superwetting silicone surfactant) after it was copolymerized in increasing weight percentages with butyl methacrylate (BMA) and/or methyl methacrylate (MMA). Interestingly, copolymers of 20 wt % ACR showed at least 3x less adhesion by Escherichia coli BL21 (E. coli) than any other formulation. This was not a consequence of wettability, which followed a parabolic function with ACR concentration: high contact angles (CA) with sessile water drops were observed at both low (< 20 wt %) and high (> 80 wt %) concentrations of ACR in materials. The CA at 20 wt % ACR was 66°. The lack of E. coli adhesion was ascribed to surfactant-membrane interactions; hence, the antibacterial potential of compounds related to ACR was further probed. Chapter 3, therefore, examines the structure-activity relationships of nonionic silicone polyether surfactants in solution. Azide/alkyne click chemistry was used to prepare a series of eight compounds with consistent hydrophilic tails (8- 44 poly(ethylene glycol) units), but variable hydrophobic heads (branched silicones with 3-10 siloxane linkages, and in two cases phenyl substitutions). The compounds were tested for toxicity at 0.001 w/v %, 2.5 w/v % and their critical micelle concentrations (CMCs), against different concentrations of E. coli in a 3-step assay. Surfactants with smaller head groups had as much as 4x the bioactivity of larger analogues, with the smallest hydrophobe exhibiting potency equivalent to SDS. Smaller PEG chains were similarly associated with higher potency. This data suggests that lower micelle stability, and the theoretically enhanced permeability of smaller silicone head groups in membranes, is linked to antibacterial activity. The results further demonstrate that the simple manipulation of nonionic silicone polyether structures, leads to significant changes in antibacterial action. To ensure similar results were achievable when such surfactants are immobilized on surfaces, 8 compounds with shorter, ethoxysilylpropyl-terminated PEG chains, and branched or linear hydrophobes, were incorporated into a homemade, room temperature vulcanization (RTV) silicone (Chapter 4). The materials, containing 0- 20 wt% surfactants) were then tested for contact killing and cytophobicity against the same E. coli strain. Elastomers modified with 0.5- 1 wt% of (EtO)3Si-PEG- laurate, and separately (EtO)3Si-PEG-tBS, were on average 2x more hydrophilic relative to controls (103°) and differed in their wettability by ~40°, yet both were anti-adhesive; a ~30-fold reduction in adhesion was seen on modified surfaces relative to the control PDMS. Additionally, the (EtO)3Si-PEG-tBS surface demonstrated biocidal behavior, which further highlighted the importance of surfactant chemistry- not just wettability- in observing a specific antibacterial response (if any). Based on the data collated from each Chapter, silicone surfactants seem to have great potential as bioactive agents and warrant further systematic investigations into their mechanisms of action. In so doing, their chemistry may be optimized against different microbes for a variety of applications. In particular, their potential to create non-toxic, cytophobic silicones is particularly encouraging, given the need for anti-adhesive, biofilm preventing material surfaces. / Thesis / Doctor of Philosophy (PhD)

Tetrahydrofuran (THF) and tetrahydropyran (THP) rings are commonly found in a wide range of natural products and biologically active compounds. In total synthesis, the formation of THF/THP motifs is often the key step but existing methods often involve numerous steps and low overall efficiencies. Part one of this thesis details the development of a practical method for the synthesis of THF rings by the controlled mono-addition/cyclisation of organolithium species to C2-symmetric diepoxides (Scheme A-1). This method can also be applied to the synthesis of bis-THF rings from triepoxides and has potential applications in more complex cascade reactions. A similar cyclisation process providing THF rings from epoxyaldehydes is also described. Part two of this thesis details our efforts towards the synthesis of the marine macrolide neopeltolide. Wright and co-workers reported the isolation of neopeltolide 211 from a deep-water sponge of the family neopeltidae off the north coast of Jamaica. The structure, which was assigned by NMR and HRMS studies and reassigned by total synthesis, contains a 14-membered macrolactone, a 2,6-cis THP ring and an unsaturated oxazole side-chain. Chapter four describes the synthesis of the C2-C8 and C9-C16 fragments (Scheme A-2). Chapter five details our initial attempts in the coupling of subunits 268 and 320, as well as a revised synthetic strategy that allowed us to successfully couple C2-C9 alkyne 347 with C10-C16 aldehyde 348 and the preparation of an advanced intermediate 364 (Scheme A-3).