Additive friction stir deposition (AFSD) is an emerging solid-state metal additive manufacturing technology that uses deformation bonding to create near-net shape 3D components. As a developing technology, a deeper understanding of the processing science is necessary to establish the process-structure relationships and enable improved control of the as-printed microstructure and material properties. AFSD provides a unique opportunity to explore the friction stir fundamentals via direct observation of the material during processing. This work explores the relationship between the processing parameters (e.g., tool rotation rate Ω, tool velocity V, and material feed rate F) and the thermomechanical history of the material by process monitoring of i) the temperature evolution, ii) the force evolution, and iii) the interfacial contact state between the tool and deposited material. Empirical trends are established for the peak temperature with respect to the processing conditions for Cu and Al-Mg-Si, but a key difference is noted in the form of the power law relationship: Ω/V for Cu and Ω2/V for Al-Mg-Si. Similarly, the normal force Fz for both materials correlates to V and inversely with Ω. For Cu both parameters show comparable influence on the normal force, whereas Ω is more impactful than V for Al-Mg-Si. On the other hand, the torque Mz trends for Al-Mg-Si are consistent with the normal force trends, however for Cu there is no direct correlation between the processing parameters and the torque. These distinct relationships and thermomechanical histories are directly linked to the contact states observed during deformation monitoring of the two material systems. In Cu, the interfacial contact between the material and tool head is characterized by a full slipping condition (δ=1). In this case, interfacial friction is the dominant heat generation mechanism and compression is the primary deformation mechanism. In Al-Mg-Si, the interfacial contact is characterized by a partial slipping/sticking condition (0<δ<1), so both interfacial friction and plastic energy dissipation are important mechanisms for heat generation and material deformation. Finally, an investigation into the contact evolution at different processing parameters shows that the fraction of sticking is critically dependent on the processing parameters which has many implications on the thermomechanical processing history. / Doctor of Philosophy / Additive manufacturing or three-dimensional (3D) printing technologies have been lauded for their ability to fabricate complex geometries and multi-material parts with reduced material waste. Of particular interest is the use of metal additive manufacturing for repair and fabrication of industrial and structural components. This work focuses on characterizing the thermomechanical processing history for a developing technology Additive Friction Stir Deposition (AFSD). AFSD is solid-state additive manufacturing technology that uses frictional heat and mechanical mixing to fabricate 3D metal components. From a fundamental materials science perspective, it is imperative to understand the processing history of a material to be able to predict the performance and properties of a manufactured part. Through the use of infrared imaging, thermocouples, force sensors, and video monitoring this work is able to establish quantitative relationships between the equipment processing parameters and the processing history for Cu and Al. This work shows that there is a fundamental difference in how these two materials are processed during AFSD. In the future, these quantitative relationships can be used to validate modeling efforts and improve manufacturing quality of parts produced via friction stir techniques.

Although additive manufacturing technologies are often referred to as "3D printing," the family of technologies typically deposit material on a layer-by-layer basis. For material extrusion (ME) in particular, the deposition process results in weak inter- and intra-layer bonds that reduce mechanical performance in those directions. Despite this shortcoming, ME offers the opportunity to specifically and preferentially align the reinforcement of a composite material throughout a part by customizing the toolpath. Recent developments in multi-axis deposition have demonstrated the ability to place material outside of the XY-plane, enabling depositions to align to any 3D (i.e., non-planar) vector. Although mechanical property improvements have been demonstrated, toolpath planning capabilities are limited; the geometries and load paths are restricted to surface-based structures, rather than fully 3D load paths. By specifically planning deposition paths (roads) where the composite reinforcement is aligned to the load paths within a structure, there is an opportunity for a step-change in the mechanical properties of ME parts. To achieve this goal for arbitrary geometries and load paths, the author presents a design and process planning workflow that concurrently optimizes the topology of the part and the toolpath used to fabricate it. The workflow i) identifies the optimal structure and road directions using topology optimization (TO), ii) plans roads aligned to those optimal directions, iii) orders those roads for collision-free deposition, and iv) translates that ordered set of roads to a robot-interpretable toolpath. A TO algorithm, capable of optimizing 3D material orientations, is presented and demonstrated in the context of 2D and 3D load cases. The algorithm achieved a 38% improvement in final solution compliance for a 3D Wheel problem relative to existing TO algorithms with planar orientation optimization considerations. Optimized geometries and their associated orientation fields were then propagated with the presented alignment-focused deposition path planner and conventional toolpath planners. The presented method resulted in a 97% correlation between the road directions and the orientation field, while the conventional methods only achieved 77%. A planar multi-load case was then fabricated using each of these methods and tested in both tension and bending; the presented alignment-focused method resulted in a 108.24% and 29.25% improvement in each load case, respectively. To evaluate the workflow in a multi-axis context, an inverted Wheel problem was optimized and processed by the workflow. The resulting toolpaths were then fabricated on a multi-axis deposition platform and mechanically evaluated relative to geometrically similar structures using a conventional toolpath planner. While the alignment in the multi-axis specimen was improved from the conventional method, the mechanical properties were reduced due to limitations of the multi-axis deposition platform. / Doctor of Philosophy / The material extrusion additive manufacturing process is widely used by hobbyists and industry professionals to produce demonstration parts, but the process is often overlooked for end-use, load bearing parts. This is due to the layer-by-layer fabrication method used to create the desired geometries; the bonding between layers is weaker than the direction material is deposited. If load paths acting on the printed structure travel across those layer interfaces, the part performance will decrease. Whereas gantry-based systems are forced into this layer-by-layer strategy, robotic arms allow the deposition head to rotate, which enables depositions to be placed outside of the XY-plane (i.e., the typical layer). If depositions are appropriately planned using this flexibility, the layer interfaces can be oriented away from the load paths such that all of the load acts on the (stronger) depositions. Although this benefit has been demonstrated in literature, the existing methods for planning robotic toolpaths have limits on printability; certain load paths and geometries cannot be printed due to concerns that the robotic system will collide with the part being printed. This work focuses on increasing the generality of these toolpath planning methods by enabling any geometry and set of load paths to be printed. This is achieved through three objectives: i) identify the load paths within the structure, ii) plan roads aligned to those load paths, iii) order those roads such that collisions will not occur. The author presents and evaluates a design workflow that addresses each of these three objectives by simultaneously optimizing the geometry of the part as well as the toolpath used to fabricate it. Planar and 3D load cases are optimized, processed using the presented workflow, and then fabricated on a multi-axis deposition platform. The resulting specimens are then mechanically tested and compared to specimens fabricated using conventional toolpath planning methods.

Additive manufacturing provides unmatched control and diversity over structural design of polymeric, ceramic and metallic parts. Nevertheless, until recently, the toolbox of polymeric feedstocks for light based additive manufacturing limited employment of printed parts for applications necessitating high thermomechanical performance. Development of synthetic pathways permitted the first additive manufacturing of high performance poly(amide imides) via ultraviolet assisted direct ink write (UV-DIW) printing. Precursor resins exhibited prerequisite rheology and reactivity for UV-DIW and produced organogels were well-defined and self-supporting. Thermal treatment induced drying and imidization of the precursor organogels to form the desired poly(amide imide) structures. During post-processing the parts displayed linear isotropic shrinkage as low as 26% and exhibited competitive thermomechanical properties. Following expansion of the high performance backbones available for additive manufacturing, simplification of synthetic rigors was undertaken. This investigation facilitated the evolution of the first photocurable and processable small molecule polyimide precursors. These supramolecular carboxylate ammonium nylon salts, coined polysalts, allowed for additive manufacturing of both high performance polyimides and polyetherimides using vat photopolymerization (VP). The use of small molecule precursors over previously investigated polymeric precursors displayed much lower solution viscosities yielding reduction of organic solvent loading, inducing lower overall shrinkage. Polysalts provide a stimulating platform for rapid and facile printing of high performance polyimides in the future. Surveying the excellent carbonization behavior for aromatic polyimides spurred translation of known 2D protocols to post-processing of printed polyimides. Applying pyrolysis methodologies to parts produced using VP and UV-DIW induced efficient carbonization at 1000 °C. Remarkably, the carbonized parts retained structure and did not display cracks or pore formation. Raman spectroscopy indicated production of disordered carbon via the utilized pyrolysis protocol, in line with literature on carbonization of PMDA-ODA polyimide at 1000 °C. Electrical testing indicated production of conductive materials following pyrolysis, with carbonization temperature modulating the performance. The excellent thermal stability, transport properties, and known mechanical performance of carbonaceous materials may enable application of these printed objects in customized electronics and aerospace environments. Exploration of drop-in monomeric units permitted a multi-pronged research program into augmentation of mechanical, rheological and transport properties of high performance polyetherimides (PEIs). Installation of sodium or lithium substituted disulfonated monomers via classical two-step polyimide synthesis afforded two series of sulfonated polyetherimides (sPEI). The sPEIs exhibited robust thermal properties, with high sulfonate mol% inducing Tg > 300 °C. X-ray scattering experiments revealed the development of domains via inclusion of the sulfonate moieties, with low mol% producing larger domain spacing. The larger domains present in the low mol% sPEIs yielded improved ionic liquid uptake within 2 d, yielding improved ionic conductivities at room temperature relative to high mol% samples. The observed conductivities indicated potential of the sPEIs as battery electrolytes, but further ionic liquid incorporation is required for competitive performance. Development of a poly(ethylene glycol) (PEG) bearing macromonomer facilitated synthesis of PEIs and PI graft copolymers. When coupled with 4,4'-(4,4'-isopropylidene-diphenoxy)diphthalic anhydride (BPADA) and meta-phenylene diamine (mPD), the PEG-grafted materials exhibited signs of phase mixing at low mol% incorporation of macromonomer, with a single observable Tg depressed from neat BPADA-mPD. Doping of the PEI-g-PEG with lithium salts allowed for production of polymeric films that displayed good ionic conductivities at room temperatures. Extension of the PEG macromonomer into fully aromatic PIs yielded phase separated materials even at modest loadings, >2.5 mol%. The formed PEG-g-PMDA-ODA contained thermally stable PI main-chains with thermally labile graft chains, which when thermally treated induced facile quantitative PEG removal. Remarkably, the thermally treated materials retained flexibility, even at >60 wt.% PEG removal. Further investigations aim to explore use of novel PEIs in energy storage as well as low density and dielectric materials. / Doctor of Philosophy / High performance polymers enjoy wide use in microelectronics and aerospace industries due to high thermal stability and excellent mechanical performance. However, processing restrictions hinder manufacturing of 3-dimensional objects of many high performance polymers suitable for extreme environments. Additive manufacturing, also known as 3D printing, has garnered attention in both academic and industrial settings over the last four decades due to the unmatched control over part design and internal structure, but the material arsenal for additive manufacturing of polymers lacks options for applications demanding high thermal stability. The first half of this dissertation aimed to promote translation of high performance polymeric chemistries to suitable feedstocks for additive manufacturing. By designing and developing novel chemical pathways, traditional processing limitations were circumvented and high performance polymers, such as poly(amide imides) and polyimides, were successfully processed via light based additive manufacturing. Likewise, by investigating carbonization dynamics of polyimides and expanding current additive manufacturing techniques for processing of fully aromatic polyimides, complex 3D carbonaceous materials were obtained. These carbon objects present extreme thermal stability and electrical conductivity, advantageous for aerospace and electronic industries. Additionally, investigations allowed for development of synthetically facile routes for expanding the available polyimide backbones for additive manufacturing via use of small molecule precursors. The second half of the dissertation explored novel polyetherimide and polyimide reagents for production of functional materials. Harnessing ionic building blocks permitted synthesis of a series of thermally robust polyetherimides displaying promise for energy storage. Similarly, coupling previous literature for ion conduction in solid polymer electrolytes for battery applications with thermally stable and flame resistant polyetherimides enabled synthesis of a series of innovative graft copolymers with good room temperature ionic conductivities. Lastly, pairing of thermally labile polymers with thermally resistant polyimide backbones allowed for development of an exciting platform for obtaining highly insulting and flexible films for electronics applications. Outlined future work aims to probe the formation of pores in the obtained polymer

Additive manufacturing (AM) is a powerful emerging technology for fabricating components with complex geometries using a variety of materials. However, despite the promising potential, due to the complexity of the process dynamics, how to ensure product quality and consistency of AM parts efficiently during the process remains challenging. Therefore, this dissertation aims to develop advanced machine learning methods for online process monitoring and quality assurance of smart additive manufacturing. Driven by edge computing, the Industrial Internet of Things (IIoT), sensors and other smart technologies, data collection, communication, analytics, and control are infiltrating every aspect of manufacturing. The data provides excellent opportunities to improve and revolutionize manufacturing for both quality and productivity. Despite the massive volume of data generated during a very short time, approximately 90 percent of data gets wasted or unused. The goal of sensing and data analytics for advanced manufacturing is to capture the full insight that data and analytics can discover to help address the most pressing problems. To achieve the above goal, several data-driven approaches have been developed in this dissertation to achieve effective data preprocessing, feature extraction, and inverse design. We also develop related theories for these data-driven approaches to guarantee their performance. The performances have been validated using sensor data from AM processes. Specifically, four new methodologies are proposed and implemented as listed below: 1. To make the unqualified thermal data meet the spatial and temporal resolution requirement of microstructure prediction, a super resolution for multi-sources image stream data using smooth and sparse tensor completion is proposed and applied to data acquisition of additive manufacturing. The qualified thermal data is able to extract useful information like boundary velocity, thermal gradient, etc. 2. To effectively extract features for high dimensional data with limited samples, a clustered discriminant regression is created for classification problems in healthcare and additive manufacturing. The proposed feature extraction method together with classic classifiers can achieve better classification performance than the convolutional neural network for image classification. 3. To extract the melt pool information from the processed X-ray video in metal AM process, a smooth sparse Robust Tensor Decomposition model is devised to decompose the data into the static background, smooth foreground, and noise, respectively. The proposed method exhibits superior performance in extracting the melt pool information on X-ray data. 4. To learn the material property for different printing settings, a multi-task Gaussian process upper confidence bound is developed for the sequential experiment design, where a no-regret algorithm is implemented. The proposed algorithm aims to learn the optimal material property for different printing settings. By fully utilizing the sensor data with innovative data analytics, the above-proposed methodologies are used to perform interdisciplinary research, promote technical innovations, and achieve balanced theoretical/practical advancements. In addition, these methodologies are inherently integrated into a generic framework. Thus, they can be easily extended to other manufacturing processes, systems, or even other application areas such as healthcare systems. / Doctor of Philosophy / Additive manufacturing (AM) technology is rapidly changing the industry, and data from various sensors and simulation software can further improve AM product quality. The objective of this dissertation is to develop methodologies for process monitoring and quality assurance using advanced data analytics. In this dissertation, four new methodologies are developed to address the problems of unqualified data, high dimensional data with limited samples, and inverse design. Related theories are also studied to identify the conditions by which the performance of the developed methodologies can be guaranteed. To validate the effectiveness and efficiency of proposed methodologies, various data sets from sensors and simulation software are used for testing and validation. The results demonstrate that the proposed methods are promising for different AM applications. The future applications of the accomplished work in this dissertation are not just limited to AM. The developed methodologies can be easily transferred for applications in other domains such as healthcare, computer vision, etc.

Filament-based material extrusion (MatEx) additive manufacturing has garnered huge interest in both academic and industrial communities. Moreover, there is an increasing need to expand the material catalog for MatEx to produce end use parts for a wide variety of functional applications. Current approaches towards MatEx of semicrystalline thermoplastics are in their nascent stage with fiber reinforcements being one of the most common techniques. MatEx of commodity semicrystalline thermoplastics has been investigated but most of the current methods are extremely material and machine specific. The goal of this dissertation is to enable MatEx of semicrystalline polymers with mechanical properties approaching that of injection molded parts. Tailored molecular architectures of blends that can control the crystallization kinetics from the melt state are investigated. By modifying the crystallization time window, the time during which chain diffusion can occur across the deposited layers is prolonged, which allows for a stronger bond between layers. Such differences in the crystallization process impact the z-axis adhesion and residual stress state, which directly affect mechanical properties and warpage in the printed parts. The impact of blend composition on polymer chain diffusion, crystallization profiles, and print properties resulting from the repeated non-uniform thermal history in filament based MatEx is studied. The melt flow behaviour is characterized using rheology and its effect on the interlayer adhesion of printed parts and print precision is explored. The extent of polymer chain re-entanglement post deposition on the printer bed is quantitatively determined using interrupted shear rheology protocols. Tensile bars are printed and mechanically characterized to analyze the tensile performance of the printed parts. Correlating the rheological findings with the mechanical performance of the printed parts provides valuable insights into the complex interlayer welding process during MatEx and is critical to improving existing machine designs and feedstocks in order to achieve printed parts with properties approaching their injection molded counterparts. The results will be essential in identifying optimal processing conditions to maximize material specific printed part performance as well as highlight the associated limitations to enable MatEx of next generation materials. / Doctor of Philosophy / Compared to traditional subtractive manufacturing techniques, additive manufacturing (AM) has the potential to transform modern manufacturing capabilities due to its unique advantages including design flexibility, mass customization, energy efficiency, and economic viability. The filament-based material extrusion (MatEx), also referred to as fused filament fabrication (FFF), employing thermoplastic polymers (and composites) has emerged as one of the most common AM modality for industrial adoption due to its operational simplicity. However, the widespread application of MatEx has been limited due to the lack of compatible materials, anisotropic mechanical properties, and lack of quality assurance. Most of the research on FFF has been performed on amorphous polymers with almost negligible levels of crystalline content such as polylactic acid (PLA) and acrylonitrile-butadiene-styrene (ABS). Semicrystalline polymers are an attractive choice for FFF feedstocks compared to the amorphous ones due to their improved thermal resistance, toughness, and deformability. However, processing semicrystalline polymers using FFF is challenging due to the volumetric shrinkage encountered during crystallization from the melt state. This results in the buildup of significant levels of residual stresses at temperatures lower than the crystallization temperature of the polymer resulting in warpage of the printed parts. The research presented in this dissertation aims to address the aforementioned challenges by characterizing semicrystalline polymer feedstocks under conditions representative of the multiphysics encountered during a typical FFF process. Several strategies to limit shrinkage and warpage are discussed that involve tuning the thermal profile and crystallization kinetics during printing. The former is achieved by addition of thermally conductive carbon fiber reinforcements while the latter is realized by blending amorphous resins or low crystallinity polymers to the semicrystalline polymer matrix. The fibers results in a more homogenous temperature distribution during printing while the incorporation of the resins modify the rate of crystallization; both of which play a pivotal role in reducing the residual stress build-up and hence minimizing the warpage during printing. The printability of the materials is investigated based on the shear- and temperature dependent viscous response of the polymers. The printed parts with fiber reinforcements exhibit high levels of mechanical anisotropy compared to the blends with the resins, likely due to differences in polymer chain mobility at the interface. The tensile properties of the printed polymer blends are slightly inferior to those obtained using traditional manufacturing techniques; however, properties close to 90-95% of injection molded properties are recovered through a simple post-processing thermal annealing step. The obtained results will assist in optimizing the processing parameters and feedstock formulation in order to consistently produce printed parts with minimal defects and tailored mechanical properties for functional applications.

In the aerospace propulsion sector safety is an important driver to costs, vehicle design and mission capabilities. Hybrid rockets are considered some of the safest forms of chemical propulsion. That factor alone makes hybrid rocket propulsion systems desirable options. Hybrid systems often benefit from multiple additional advantages over conventional solid and liquid propellant systems, including: minimal environmental impact, higher density impulses, start-stop-restart capabilities, simplistic random throttle control, low development costs, and basic transportation and storage requirements. A major issue that continues to impact the effective use of hybrid systems, is that classical hybrid rocket fuels suffer in low regression rates. If fuel regression rates can be improved upon without diminishing any of the other beneficial factors to a hybrid rocket motor then a far greater market for such systems can be generated. In this work, additively manufactured polypropylene solid fuel grains were infused with gels as a means of significantly altering the fuel burning rates in a lab scale hybrid rocket motor. Gels based on Jet-A were created using both particulate (fumed silica, micro aluminum, nano aluminum) and polymeric (paraffin wax) gellants. The particle structure of the aluminum powders was characterized by means of microscopic imaging, particle size measurement, and thermal mass response analysis. The rheological behavior of the gels was characterized in order to determine the relationship between melt layer viscosity, viscoelastic properties, and combustion performance. High speed color video recording was used on select grains for spatially and temporally resolved three-color camera pyrometry analysis. The process showed promise in determining aluminized gel burn time across an entire rocket firing. The performance of the gel infused grains was compared to a traditional center perforated fuel grain, under similar flows of gaseous oxygen. Rocket motors fired with gel infused grains exhibited pressure increases of greater than 40%. Gel infused fuel grains demonstrated regression rate enhancements up to 90% higher than the baseline. The estimated gel regression rates were over 500% higher than the host polypropylene fuel. When the O/F was maintained near stoichiometric or lean conditions, c∗ efficiencies of the gel infused grains were similar to that of the baseline indicating thorough combustion of the gels. At low oxygen mass flows, the effects of gel infusion are not as significant, which is consistent with the liquefying fuel entrainment concept. / Master of Science / In the field of air and space flight, safety is an important driver to costs, vehicle design and mission capabilities. Hybrid rockets are considered some of the safest forms of vehicle lift systems compared to similar forms. That factor alone makes hybrid rockets desirable options. Hybrid systems often benefit from multiple additional advantages over similar systems often used, including: minimal environmental impact, greater force for a given time and volume of fuel, start-stop-restart capabilities, simplistic random motor control, low development costs, and basic transportation and storage requirements. A major issue that continues to impact the effective use of hybrid systems is that classical hybrid rocket fuels suffer in low burn rates. If fuel burn rates can be improved upon without diminishing any of the other beneficial factors to a hybrid rocket motor then a far greater market for such systems can be generated. In this work, specially manufactured solid fuel grains were combined with gels as a means of significantly altering the fuel burning rates in a small scale test setup. Gels based on a type of jet fuel were created using multiple gel forming and modifying materials. The structure of two types of small scale aluminum powders was characterized by means of microscopic imaging, particle size measurement, and weight response to thermal changes. Properties specific to the gels were characterized in order to determine performance relationships to individual material properties. High speed color video recording was used on select grains for space and time resolved three-color camera temperature analysis. The process showed promise in determining aluminized gel burn time across an entire rocket firing. The performance of the gel modified grains was compared to a traditional fuel grain design, under similar flows of gaseous oxygen. Rocket motors fired with gel modified grains exhibited pressure increases of greater than 40%. Gel modified fuel grains demonstrated burn rate enhancements up to 90% higher than the traditional fuel grain design. The estimated gel burn rates were over 500% higher than the host polypropylene fuel. When ideal conditions were maintained, fuel burn efficiencies of the gel modified grains were similar to that of the traditional fuel grain design indicating ideal burning of the gels. At low oxygen flow rates, the effects of gel addition are not as significant, which is consistent with an expectant similar concept.

In this thesis, we develop a new method for Additive Manufacturing of felt to make three dimensional objects. Felting is a method of intertwining fibers to make a piece of textile. In this work, a 6 DOF UR-5 robotic arm equipped with a 3 DOF tool head to test various approaches to using felting. Due to the novelty of this approach several different control architectures and methodologies are presented. We created felted test samples using a range of processing conditions, and tested them in an Instron machine. Samples were tested parallel to the roving fiber direction and perpendicular to the roving fiber direction. Additionally, two pieces of felt were attached to each other with needling, and these were tested with T-peel tests, pulling both in the direction of the roving fibers and perpendicular to the fibers. We present results for the Young's Modulus and Ultimate Strength of each of these samples. It is anticipated that given the appropriate combination of materials and robotic tooling, this method could be used to make parts for a multitude of applications ranging from custom footwear to advanced composites. / Master of Science / In this paper a new approach to Additive Manufacturing centered on mechanically binding fibers together into a cohesive part is presented. This is accomplished via a robotic system and a process called felting, whereby needles push fibers into each other, entangling them. To validate this approach each system and method was tested individually. We present the results of mechanical tests of a variety of felted samples. Given the results, it is believed that robotic needle felting may be a beneficial method of manufacture for several fields, and it has the potential to easily make customized products.

Consumer additive manufacturing (3D printing) has rapidly grown over the last decade. While the technology for the most common type, Fused Filament Fabrication (FFF), has systematically improved and sales have increased, fundamentally, the capabilities of the machines have remained the same. FFF printers are still limited to depositing layers onto a flat build plate. This makes it difficult to combine consumer AM with other objects. While consumer AM promises to allow us to customize our world, the reality has fallen short. The ability to directly modify existing objects presents numerous possibilities to the consumer: personalization, adding functionality, improving functionality, repair, and novel multi-material manufacturing processes. Indeed, similar goals for industrial manufacturing drove the research and development of technologies like direct write and directed energy deposition which can deposit layers onto uneven surfaces. Replicating these capabilities on consumer 3-axis FFF machines is difficult mainly due to issues with reliability, repeatability, and quality. This thesis proposes, demonstrates, and tests a method for scanning and printing dimensionally-accurate (unwarped) digital forms onto physical objects using a modified consumer-grade 3D printer. It then provides an analysis of the machine design considerations and critical process parameters. / Master of Science / Consumer additive manufacturing (3D printing) has rapidly grown over the last decade. While the technology for the most common type, Fused Filament Fabrication (FFF), has systematically improved and sales have increased, fundamentally, the capabilities of the machines have remained the same. FFF printers are still limited to depositing layers onto a flat build plate. This makes it difficult to combine consumer AM with other objects. While consumer AM promises to allow us to customize our world, the reality has fallen short. The ability to directly modify existing objects presents numerous possibilities to the consumer: personalization, adding functionality, improving functionality, repair, and novel multi-material manufacturing processes. Indeed, similar goals for industrial manufacturing drove the research and development of technologies like direct write and directed energy deposition which can deposit layers onto uneven surfaces. Replicating these capabilities on consumer 3-axis FFF machines is difficult mainly due to issues with reliability, repeatability, and quality. This thesis proposes, demonstrates, and tests a method for scanning and printing dimensionally-accurate (unwarped) digital forms onto physical objects using a modified consumer-grade 3D printer. It then provides an analysis of the machine design considerations and critical process parameters.

Unlike traditional stochastic scaffold fabrication techniques, additive manufacturing (AM) can be used to create tissue-specific three-dimensional scaffolds with controlled porosity and pore geometry (meso-structure). However, due to the relatively few biocompatible materials available for processing in AM machines, direct fabrication of tissue scaffolds is limited. To alleviate material limitations and improve feature resolution, a new indirect scaffold fabrication method is developed. A four step fabrication process is explored: Fused Deposition Modeling (FDM) is used to fabricate scaffold patterns of varied pore size and geometry. Next, scaffold patterns are surface treated, and then mineralized via simulated body fluid (SBF); forming a bone-like ceramic throughout the scaffold pattern. Finally, mineralized patterns are heat treated to pyrolyze the pattern and sinter the minerals. Two scaffold meso-structures are tested: "tube" and "backfill." Two pattern materials are tested [acrylonitrile butadiene styrene (ABS) and investment cast wax (ICW)] to determine which material is the most appropriate for mineralization and sintering. Mineralization is improved through plasma surface treatment and dynamic flow conditions. Appropriate burnout and sintering temperatures to remove pattern material are determined experimentally. While the "tube scaffolds" were found to fail structurally, "backfill scaffolds" were successfully created using the new fabrication process. The "backfill scaffold" meso-structure had wall thicknesses of 470 – 530 µm and internal channel diameters of 280 – 340 µm, which is in the range of appropriate pore size for bone tissue engineering. "Backfill scaffolds" alleviated material limitations, and had improved feature resolution compared to current indirect scaffold fabrication processes. / Master of Science

Ion-containing macromolecules continue to stimulate new opportunities for emerging electro-active applications ranging from high performance energy devices to water purification membranes. Progress in polymer synthesis and engineering now permit well-defined, ion-containing macromolecules with tunable morphologies, mechanical performance, ion conductivity, and 3D structure in order to address these globally challenged technologies. Achieving tailored chemical compositions with high degrees of phase separation for optimizing conductivity and water adsorption remains a constant synthetic challenge and presents an exciting opportunity for engineering sophisticated macromolecular architectures. This dissertation will introduce unprecedented charged polymers using conventional free radical and anionic polymerization to incorporate ionic functionalities based on phosphonium cations. This new class of copolymers offers unique properties with ionic functionality for tailorable electro-active performance. / Ph. D.