Electronics, especially, printed circuit boards (PCBs) are a widespread technology. Metal coatings or “surface finishes” are often added to PCB board pads and component leads during manufacturing to improve their performance. Electroplated nickel/gold over copper is a popular surface finish for printed circuit boards and component leads. The presence of gold in solder joints, however, is known to have detrimental effects referred to as gold embrittlement. It is generally understood that tin-lead solder joints with less than 3 weight percent (wt%) of gold will not experience reliability issues. The acceptable level of gold in lead-free solder joints, however, is less well understood, as the technology is younger. The purpose of this study was to investigate the effect of gold content on the microstructural evolution of SnAgCu solder joints. Three integrated circuit packages with various thicknesses of gold coatings were assembled on boards that were made with thin (flash) or thick gold over nickel coatings. The boards were divided into three groups based on the isothermal aging they underwent: 0 days, 30 days, or 56 days of aging at 125 °C. Thirty four of the forty boards then underwent mechanical reliability testing. Components were cross-sectioned and polished. Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS/EDX) were used to characterize the morphology and elemental composition of the solder joints and any intermetallic compounds (IMCs) that formed. The growth of bulk and interfacial layer IMCs in each package/board system was studied. In thick gold boards, AuSn4 particles observed in the bulk solder grew larger over time, absorbed Ni, and migrated to the component and board interfaces. (Cu1-p-qAupNiq)6Sn5 and (Au1-xNix)Sn4 IMCs were found at most board and component interfaces after aging. It was observed that most fractures occurred in or along the (Au1-xNix)Sn4 IMCs. Cracks were observed within IMC particles in the bulk solder, along the boardside and component side interfaces, and in the bulk solder traveling toward voids. Components with joint Au contents higher than 10 wt% had unacceptably poor reliability. The conclusion of this work is that gold content of SAC305 solder joints on boards with Au over Ni surface finishes should be kept below 3 wt% to conservatively minimize the risk of creating a microstructure that has poor reliability.

Diels-Alder chemistry was utilized to manipulate the surface energy of glass substrates in reversible manner. Glass slides and capillaries were functionalized with hydrophobic dieneophiles resulting in a non-wetting surface. A retro Diels-Alder reaction facilitated by the thermal treatment of the surface’s function to cleave the hydrophobic dieneophile and resulted in the fabrication of a hydrophilic surface. Contact angle (CA) measurements were used as preliminary measurements for monitoring the changes in surface energy exhibited during the initial hydrophobic state (CA - 70±3°), after attachment of the dieneophile creating a hydrophobic state (CA - 101±9°) followed by reestablishment of the hydrophilic state (CA - 70±6°) upon cleavage of the Diels-Alder adduct. The treatments developed on flat glass surfaces were transferred to glass capillaries, with effective treatment confirmed by fluid column measurements. Effective flow gating was developed in the capillaries via patterning of the surface with hydrophilic/hydrophobic regions. Finally, attempts to create self-pressurizing capillaries were unsuccessful due to pronounced contact angle hysteresis for the hydrophobic surface treatment. Indium-tin oxide (ITO) substrates were functionalized with successive surface intiated atom transfer radical polymerization (SI-ATRP) and electropolymerization. A novel hybrid styrenic/thiophene monomer (ProDOT-Sty) was synthesized and employed in the polymerization events. This unique monomer and combination of polymerization methods allowed for the templation of electropolymerized poly(3,4-alkyleneoxythiophene) brushes by first creating a poly(styrene) backbone via SI-ATRP. An ITO electrode functionalized with poly(ProDOT-Sty) brushes grafted from the ITO surface via SI-ATRP was analyzed via cyclic voltammetry which clearly indicated the electropolymerization event beginning at approximately +0.7 V vs Fc/Fc+. Photo patterning of the phosphonic acid ATRP initiator immobilized on the ITO surface was undertaken in order to create a surface that would limit growth of the polymer species to a patterned area for facile film brush thickness characterization via atomic force microscopy (AFM) at a later time. This was accomplished via lithography with ultraviolet radiation (UV) and was confirmed via scanning electron microscopy (SEM). A nanohetero structure composed of platinum tipped cadmium selenide seeded, cadium sulfide nanorods (CdSe@CdS-Pt NRs). CdSe quantum dots (QDs) with variable sizes were prepared by adjusting reaction temperatures and times. CdS nanorods were then grown utilizing the CdSe QDs as seeds. Various lengths of the CdSe@CdS NRs were produced that ranged from ~25 nm to ~135 nm. Investigation of the influence of the various synthetic conditions of the nanorod synthesis led to the conclusion that the ratio of CdSe seeds to Cd and S precursors could be manipulated in order to influence the length to which the nanorods grew. Pt tips were attached to an end of the CdSe@CdS nanorods as photocatalytic hydrogen production sites. TEM was utilized to characterize the different types of nanoparticles at each stage of assembly.

ABSTRACT THE EFFECTS OF COLOR CONCENTRATES ON THE RHEOLOGY OF TINT BASES Douglas James Herrick Waterborne coatings are formulated with a number of different ingredients; water, latex polymers, pigments, surfactants, dispersants, defoamers, biocides, coalescing aids, and rheology modifiers or thickeners. Rheology modifiers are necessary in order to improve the physical properties of the coating before, during, and after application to a substrate. There are two kinds of rheology modifiers used in waterborne coatings; associative thickeners and non-associative thickeners. Coatings formulated with associative thickeners are quite sensitive to coating variations; the slightest change in the formulation has profound effects on the rheology of the coating. The opposite is true for coatings formulated with non-associative thickeners, where the rheology of the coating is not affected by minor changes in the formulation. The rheological properties of coatings are most influenced by the latex, thickener, and surfactant components of the coating. Previous studies have shown that the most ideal balance of rheological properties come from using associative thickeners. However, when waterborne coatings with associative thickeners are tinted with colorants containing high levels of surfactants they exhibit a significant decrease in viscosity. This change in viscosity results in poor sag resistance, poor brush loading, and may also cause a reduction in tint strength of the coating. In this work, the effect of tinting paints with six different colorants on the viscosity of the paint was studied for four different paint formulations: a pastel base and a deeptone base formulated with hydroxyethylcellulose (HEC-type) non-associative thickeners, and a pastel base and a deeptone base formulated with hydrophobically-modified, ethoxylated polyurethane (HEUR-type) associative thickeners. Gloss values and tinting strengths were obtained in accordance with ASTM methods D523-08 and D4838-88. In addition, dynamic stress and frequency sweeps were taken in order to study the effect of colorant addition on the viscoelastic properties of each sample. Colorant addition had little to no effects on the viscosity of the bases formulated with HEC thickeners, while there was a dramatic decrease in viscosity upon colorant addition to the bases with HEUR thickeners. Similar results were observed in the viscoelastic property analysis: little to no effects on the elastic and viscous moduli was seen with the tinted coatings formulated with the non-associative thickeners, while both the elastic and viscous moduli decreased for the coatings formulated with associative thickeners. A few of the deeptone bases showed increased moduli upon tinting compared to the parent deeptone base. The addition of colorant resulted in a decrease in tinting strength and an increase in gloss for those samples with associative thickeners, while the opposite was found for those samples with non-associative thickeners.

Covalent organic frameworks (COFs) are a novel class of crystalline materials with regular porosity, high specific surface area, and various linkage chemistries. Conventional chemical syntheses of these materials lead to the formation of bulk powders characterized as polycrystalline aggregates. Synthesizing these materials as colloidal systems is an effective means to prevent aggregation and achieve larger single-crystalline domain sizes. In this thesis, I describe the effect of temperature and transimination catalyst strength on COF particle nucleation and particle growth. Morphology and crystallinity of the COF-300 particles were confirmed using X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). The onset of colloidal light scattering, or the Tyndall Effect, was measured using Dynamic Light Scattering (DLS). Reaction temperature affects both the reaction rate and the solubility of the monomeric and oligomeric species. The higher solubility at higher temperatures is hypothesized to delay particle nucleation, or the onset of colloidal light scattering. DLS measurements confirmed these results. However, measurement of particle size using DLS and SEM showed little association between the particle size and reaction temperature. Stronger acids are similarly hypothesized to accelerate the chemical reaction, leading to a shorter induction delay and smaller particles. DLS measurements confirmed this hypothesis on the effect of acid catalyst on the induction delay; stronger acids led to a v shorter induction delay. However, preliminary SEM measurements suggest that stronger acid catalysts create larger COF-300 particles.

High performance carbon fibers (CFs) have been a commercially available since their commercial boom in the 1970s, and are generally produced via carbonization of poly (acrylonitrile) (PAN). More recently, carbon nanomaterials like graphene and carbon nanotubes (CNTs) have been discovered and have shown excellent mechanical, thermal, and electrical properties due to their sp2 carbon repeating structure. Graphene and CNTs can both be organized into macroscopic fibers using a number of different techniques, resulting in fibers with promising mechanical performance that can be readily multifunctionalized. In some cases, the two materials have been combined, and the resulting hybrid fibers have been shown to display synergistically enhanced mechanical properties. The incredible intrinsic properties of graphene and CNTs has never been fully realized in their fiber assemblies, so part of the aim of this work is to discover methods to improve upon the performance of nanocarbon based fibers. Carbon nanomaterials can be difficult to work with because of the difficulty in processing them into commercially viable materials, and the challenges associated with scalable production techniques. So, the main goal of this work is to prepare hybrid graphene and CNT based fibers with optimal mechanical performance using simple, cost-effective methods.

The global transition to renewable energy sources is placing high demands on the development of effective energy storage methods, the most prevalent being batteries. Dual-ion batteries are a new battery technology that takes advantage of the simultaneous intercalation of both cations and anions. Dual-ion batteries can be made from environmentally friendly materials such as organic compounds or conductive polymers that are made up of highly abundant elements. These often have a lower cell voltage than metal-based batteries, allowing water-based electrolytes to be used without decomposing. This master’s thesis presents the synthesis, and electrochemical testing of a nanofibrous polyaniline cathode. It also presents the synthesis and electrochemical testing of two anodes being and graphene-enhanced polyimide, and perylene tetracarboxylic diimide (PTCDI). Aqueous ammonium sulfate of 1 M or 3 M concentration is used as electrolyte. A novel full-cell dual-ion battery is also constructed using polyaniline and PTCDI as electrodes. The addition of graphene to polyimide results in changes in morphology with decreased pore size and increased surface area for supposed improved reaction kinetics with the electrolyte. The electrochemical testing of this anode is however not successful. The polyaniline cathode has an early charge/discharge capacity of 184.5/85.2 mAh/g that decreases to 40.4/45.8 mAh/g after 100 cycles. The PTCDI anode has an early charge/discharge capacity of 80.2/87.3 mAh/g but cannot be evaluated after a few cycles due to electrolyte decomposition. For this reason, the electrolyte dependence on ammonium sulfate concentration is also investigated. An increase in molarity from 1 M to 3 M leads to increased stability of the electrolyte. The polyaniline//PTCDI full-cell has a voltage of 1.2 V and shows an early charge/discharge capacity of 17.6/11.9 mAh/g that decreases to 9.1/7.2 mAh/g after 100 cycles where the efficiency stabilizes at 80%.

The purpose of this lab was to investigate the printability of cellulose nanofiber/carbon nanotubes, their functions as actuators, and to compare these properties with MXene/nano cellulose gels. Data on MXene/nano cellulose gel was obtained from previous research made by Hamedi labs. Data on carbon nanotubes were collected through experiments evaluating different concentrations and sonication times to yield a gel with high conductivity and viscosity. While it was concluded that both gels could be printed into 2D or 3D shapes, the latter failed to maintain its structure over time due to issues with drying. However, it was found that only 2D MXene/CNF could be used as a reversible actuator. / Syftet med laborationen var att undersöka 3D skrivningsförmågan för nanocellulosa/ kolnanorör samt samt deras förmåga att fungera att svälla elektroniskt. Vidare jämfördes dessa egenskaper med MXene/nanocellulosageler. Data på MXene/nanocellulosa insamlades från tidigare experiment gjorda av Hamedi labs. Data på kolnanorör insamlades genom en rad experiment, vilka utvärderade olika koncentrationer och sonikeringstider för att producera geler med hög konduktivitet och viskositet. Slutsatsen blev att båda gelerna kunde 3D printas, men endast MXene/nanocellulosageler kunde användas för elektronisk svällning och avsvällning. Inga geler kunde göras till 3D strukturer.

A host of environmental issues will define the state of the environment in the 21st century, with plastic pollution and water shortages among them. While solutions to these problems require large-scale, multipronged solutions, one way we can address them is through material innovation and the use of nanoparticles. In the first project, we address the issue of plastic pollution by creating nanocomposites of biodegradable polymers (PLA and PCL) with cellulose nanofibrils. Here, PLA and PCL are grafted from the surface of cellulose nanofibrils via ring-opening polymerization of cyclic ester monomers. Polymer-grafted cellulose (PGC) is characterized with structural analysis, solubility tests, thermal properties. Graft-polymer and generated free polymer are compared to evaluate assumptions about polymerization kinetics. Lastly, environmental fate of PGC is evaluated via aerobic, anaerobic, and enzymatic biodegradation tests. In the second project, we address the issue of fresh water shortage by creating screen-printed composites of polymerizable, surfactant-templated single-wall carbon nanotubes (SWNTs). Surfactant-templated SWNTs behave as lyotropic liquid crystals (LLCs), allowing self-assembly and shear-directed alignment. Here, LLC-SWNT inks are screen-printed in micron-sized channels and polymerized with UV light. Mesophase and alignment are evaluated using SAXS. Certain methods of screen printing with a stencil are found to enhance alignment and ordering of LLC-SWNTs, allowing for enhanced desalination and ion rejection.

Understanding structure-property relationship of molecules is imperative for designing efficient materials for organic semiconductors. Organic semiconductors are based on π-conjugated molecules, either small molecules or macromolecules such as dendrimers or polymers. Charge transport through organic materials is one of the most important processes that drive organic electronic devices. We have investigated the charge transport properties in various molecular designs based on dendrons, dendron-rod-coil molecular triads, and conjugated oligomers. The charge transport properties were studied using bottom contact field effect transistors, in which the material was deposited by spin coating. In case of dendrons, their generation and density of charge transporting functionalities were found to play a significant role in influencing the charge transport properties. In case of macromolecules such as dendron-rod-coil molecules, the solid state morphology plays a significant role in influencing the charge transport properties. While these molecules exhibit only electron transporting behavior in field-effect transistor measurements, ambipolar charge transport is observed in the diode configuration. Short conjugated oligomers, based on donor-acceptor-donor design, provide model systems for conjugated polymers. Effect of varying the donor functionality on optoelectronic and charge transport properties was studied in short donor-acceptor-donor molecules. While donor-acceptor-donor molecules are well known in the literature, the effect of molecular composition on the charge transport properties is not well understood. We designed molecules with 2,1,3-benzothiadiazole as the acceptor and thiophene based donor functionalities. These molecules exhibit a reduced bandgap, good solution processability and charge mobility making them interesting systems for application in organic photovoltaics. Cyclopentadithiophene (CPD) based materials have been widely utilized as organic semiconductors due to their planar nature which favors intermolecular charge transport. While most CPD based materials are hole transporting, incorporation of electron withdrawing fluorinated substituents imparts n-type behavior to these molecules. This change in charge transport properties has often been attributed to the lowering of the LUMO energy level due to the increased electron affinity in the molecule. We designed CPD based semiconductors in which the bridgehead position was functionalized with electron withdrawing ketone or dicyanomethylene group and the -positions were substituted with phenyl or pentafluorophenyl groups. Both the phenyl substituted molecules are p-type materials, even though the dicyanomethylene group lowers the LUMO by 500 meV as compared to the carbonyl compound. The pentafluorophenyl substituted molecules are n-type materials even as their LUMO energy levels are about 300 meV higher than the corresponding phenyl substituted molecules. This indicates that charge transport behavior is not an exclusive function of the frontier orbital energy levels.

In this study a sample of particles in a size region of 0.05-10 μm were run through a centrifugation process with the ambition to make it monodisperse. The product requirements were stated as follows, particles within the size range of 2 to 3.8 μm should be isolated and separated from the sample with a D90/D10 < 1.4 where the D90/D50/D10 values should be approximately 3.8 μm/2.5 μm/2 μm. It was found that two layers of sucrose with a 50/50 volume distribution of 45w% sucrose solution and 60w% sucrose solution respectively, was the most efficient density gradient arrangement for separation of this particular sample. The optimal time and RPM combination was found to be 5 min 3000 RPM with a fast acceleration and slower deceleration, ratio 9:6. Two centrifugation rounds on the same sample improved D90/D10 drastically. The effect of centrifugation rounds on D90/D10 was not investigated further than 3 rounds, however this would be a good starting point for further studies. The upscaled test runs indicated a positive result, i.e. the yields with respect to both mass and purity were reproducible. It is worth mentioning that the upscale was only in the volume, sample load volume and surface area factors. The gradient height or particle travel distance remained the same.