Browsing by Author "Herrera-Alonso, Margarita, committee member"
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Item Embargo Advanced nanostructured materials for enhancing bioactivity(Colorado State University. Libraries, 2024) Bhattacharjee, Abhishek, author; Popat, Ketul C., advisor; Sampath, Walajabad, committee member; Herrera-Alonso, Margarita, committee member; Wang, Zhijie, committee memberHealth hazards such as pathogenic infection, communicable diseases, and bone damage and injuries cause enormous human suffering and pain worldwide. Biomaterials such as orthopedic implants and biosensors are crucial tools to remedy these complications. Development of novel biomaterials and modifying existing materials can help enhance medical device efficacy. One of the key aspects of improving biomaterials is the utilization of nanotechnology. Nanoscale surface features can improve the interaction between materials and biological agents, thus improving their bioactivity. In this dissertation research, two different biomaterials were used for two distinct applications. Firstly, titanium, a common material for orthopedic implants, was used. Ti is a popular implant material because of its superior corrosion resistance, lightweight, and excellent biocompatibility. However, 10% of Ti implants fail each year due to pathogenic bacterial infection and poor osseointegration resulting in revision surgeries and immense suffering of the patients. Nanostructured surface modification approaches can potentially reduce the failure rate of Ti implants. In this study, TiO2 nanotube arrays (NT) were fabricated followed by zinc (Zn) and strontium (Sr) doping. These elements provide important signals to mesenchymal stem cells to differentiate into osteoblasts which helps in bone healing. Zn also reduces bacterial adhesion to the implant surface. Results showed that the modified surfaces could significantly reduce bacterial adhesion and improved osseointegration properties of the mesenchymal stem cells. Secondly, a polydiacetylene (PDA)-based electrospun nanofiber biosensor was prepared that is flexible in nature for monitoring bacterial or viral infection. The nanofiber biosensor could selectively detect Gram-negative bacteria via a vivid blue-to-red color transition. Since the color transition is visible to the naked eye, the biosensor offers immense potential to be used as a screening device for Gram-negative bacterial infection in various industries such as food packaging, medical, intelligence, and national security. During the COVID-19 pandemic, the PDA biosensing platform was utilized to detect the spike (S) protein of the SARS-CoV-2. For this, the surface chemistry of the PDA fibers was modified, and a receptor protein was conjugated at the end of the PDA polymer chain. When the modified PDA fibers were incubated with the S protein, the blue-to-red color transition happened, thus sensing the presence of S protein in the environment. This result indicated that PDA nanofiber biosensor is a flexible sensing platform for effectively detecting both bacteria and viruses. The two biomaterials investigated in this research indicated that the use of nanotechnology can help in enhancing their bioactivity.Item Embargo Advancements in the chemical recyclability of acrylic polymers through investigation of monomer design(Colorado State University. Libraries, 2024) Gilsdorf, Reid Anthony, author; Chen, Eugene, advisor; Miyake, Garret, committee member; Shores, Matthew, committee member; Herrera-Alonso, Margarita, committee memberDepolymerization is a key avenue of state-of-the-art recycling of polymeric materials. Although many polymers have been investigated for their ability to depolymerize, a subset of polymers has been widely left out of the conversation, polyolefins, or polymers containing C-C bonds in the polymer main-chain. Acrylic polymers are an important class of polyolefins used throughout the world in a variety of applications. One of the key drawbacks of the polymer, however, is their unfavorable depolymerization conditions, requiring high temperatures in expensive reactors. Although much work has been performed on the depolymerization of the most widely used acrylic polymer, poly(methyl methacrylate) (PMMA), there have been few reports on trying to improve upon the recycling methods, such as decreasing depolymerization temperature or gaining control over the depolymerization mechanism. In this work, key mechanistic steps of acrylic polymer depolymerization are investigated to gain fundamental understanding on the limitations faced during depolymerization and try to improve upon them. When poly(α-methylene-γ-butyrolactone) (PMBL) and poly(α-methylene-γ-methyl-γ-butyrolactone) (PMMBL) were investigated, the suppression of side reactions that occurred with PMMA depolymerization were identified, attributed to the pendant lactone tethering radical species together. Employing this tethering effect, the design of new polymers with pendant lactones and lower equilibrium polymerization temperatures (ceiling temperature or TC), was carried out, overall decreasing depolymerization temperatures and improving polymer recyclability. Finally, these new polymers were incorporated into the design of copolymers with PMMA and PMMBL in order to exploit the new polymers' depolymerizability without hindering thermomechanical properties. Overall, this work has shed light onto the importance of polyolefin design in, not just thermomechanical properties, but also polymerization and depolymerization behavior which will benefit the continued development of recyclable-by-design polymers.Item Embargo Catalyzed chemical synthesis of designer poly(3-hydroxyalkanoate)s: tuning function, microstructure, and architecture of biodegradable polymers(Colorado State University. Libraries, 2022) Westlie, Andrea Hope, author; Chen, Eugene Y.-X., advisor; Miyake, Garret, committee member; Levinger, Nancy, committee member; Herrera-Alonso, Margarita, committee memberThis dissertation describes the development of a chemocatalytic route towards biodegradable poly(hydroxyalkanoate)s (PHAs) based on the ring-opening polymerization of eight-membered cyclic diolide, 8DL, by discrete yttrium complexes. This chemocatalytic platform has transformed the brittle, poly(3-hydroxybutyrate) (P3HB) to high performance, "designer" PHAs through the use of molecular catalysts and the development of a precision polymerization methodology. There continues to be a pressing need for biodegradable polymers in applications where material recovery is unlikely or impossible or where environmental leakage of the plastic waste is highly likely. PHAs are truly biodegradable polyesters that can degrade in ambient conditions such as aerobic soil and marine environments and these polyesters are laden with tunability enabled by their chirality, composition, and architecture. A major challenge in implementing PHAs is to achieve truly tunable thermomechanical properties for any application, coupled with desirable processing conditions at scale. A critical literature review overviews the decades-long history of various chemocatalytic routes towards PHAs with either controlled tacticity or composition. To demonstrate the scope of our chemocatalytic platform, extensive study of homo- and copolymerization of three 8DLR (R = Me, Et, Bu) has been performed. Judicious choice of catalyst to match the steric bulk of the monomer results in high activity and high stereoselectivity ROP of these uncommon PHA homopolymers and allows for highly precise random copolymers of rac-8DLMe with targeted compositions ranging from 5 ~ 40 % incorporation of 8DLR (R = Et, Bu). Moving from aliphatic to aromatic substituents allowed for the synthesis of unnatural and previously unknown PHA with a glass transition (Tg) above room temperature (RT). Aliphatic-aromatic copolymers with designed architecture as random or block copolymers could be synthesized as well. And finally, recently we have designed and synthesized discrete PHA triblock copolymers towards achieving thermoplastic elastomer materials. Overall, this work has used fundamental investigation into a stereoselective, coordination-insertion polymerization mechanism and the resulting structure-property relationships to design higher-performance PHAs that are, in some cases, competitive with commodity polyolefins. This work serves as a platform for further development of PHAs using this chemocatalytic route towards new topologies, compositions, and functions.Item Embargo Cu-P-Se nanoparticles: understanding the reaction pathways for the colloidal synthesis of energy conversion and storage materials(Colorado State University. Libraries, 2024) Neisius, Nathan A., author; Prieto, Amy L., advisor; Finke, Richard, committee member; Herrera-Alonso, Margarita, committee member; Paton, Robert, committee memberNanotechnology has garnered considerable interest over the last 40 years, owing to the unique, desirable properties that can be targeted through established synthetic methods for tuning the size of materials at the nanoscale. As no one single material has properties suitable for a wide range of applications, property driven synthesis has been at the forefront of the nanoparticle (NP) field. Particularly, colloidal NP syntheses provide a large synthetic landscape to explore as a result of the vast synthetic tunability to target specific parameters such as, particle size, morphology, composition, and defects. Although significant efforts have been made toward deciphering the transformation processes of unary and binary NPs, traditionally the colloidal NP field has been driven by a top-down approach, driven by trial-and-error methods, limiting the design of desired, complex materials. Thus, to further progress nanoparticle technology, understanding the underlying transformation processes occurring throughout the formation of colloidal nanoparticles is essential to develop novel materials as well as control the structure/property relationships. The copious amounts of both organic and inorganic interactions, as well as the complexity of capturing the transformation from molecular to the solid-state regime, complicates the reaction landscape for more complex, ternary phases. The purpose of the work included and explained in this dissertation is to develop stoichiometric syntheses for both Cu-P-Se ternary phases, Cu3PSe4 and Cu7PSe6, and to then understand the reaction pathways for an improved retrosynthetic analysis and enable translation of the synthetic knowledge to other systems. Cu-P-Se ternary chalcogenide NPs are of particular interest, owing to the synthetic complexity of navigating a rich phase space with thermodynamically stable binary phases close in energy to the desired ternary phases, as well as applicable structural properties for thermoelectrics, photovoltaics, and battery applications. Therefore, to contribute to the progression of the nanoparticle field the general objectives of this study are, (1) analyzing the transformation of commonly employed precursors and solvents (2) capture the influence of precursor reactivity on ternary phase formation, and (3) perform careful characterization of speciation and final nanoparticles, all of which to establish a full scope of Cu-P-Se nanoparticle formation and the impact of individual synthetic parameters on chalcogenide-based precursors. In Chapter 1, the relevant literature for the following chapters is reported and reviewed to provide the essential background information. This chapter is divided into 6 subsections; (1) Need for renewable energy and how nanoparticles provide solutions, (2) State of nanoparticle synthesis field, current limitations, and progress towards developing a better understanding of nanoparticle reaction pathways, (3) Motivation for exploring the Cu-P-Se phase space, (4) Se reactivity in NP syntheses, (5) Cu3P – the required precursor for Cu-P-Se formation, (6) Dissertation overview, publications, and presentations. The first colloidal NP synthesis report on Cu3PSe4 was developed by a previous group member, Dr. Jennifer Lee, which demonstrated that the phase purity of Cu3PSe4 requires the use of Cu3P NPs and selenium powder (Se) in ODE as precursors. Alternate reaction precursors, and therefore pathways, were disproven throughout this study, leading to the working hypothesis that the interactions of Se and ODE were a necessary step to form active species that then react with Cu3P NPs. Although frequently employed in NP research, and heavily characterized, the implications of the Se/ODE solution on Cu3PSe4 phase formation are still misunderstood. Therefore, the studies presented in Chapter 2 are aimed at probing the Cu3PSe4 reaction landscape and the findings are separated into (1) ex situ reactions that are characterized with molecular and solid-state characterization techniques to determine the implications of the solution dynamics on Cu-P-Se NP phase formation, and (2) how different Se/ODE speciation can be isolated and subsequently favor the alternate, metastable Cu-P-Se phase, Cu7PSe6. A persistent limitation to the previous study is that ODE contaminates the final products, making the findings and analysis of Se/ODE rather difficult to interpret, thus requiring a simplified, cleaner reaction to produce phase pure Cu3PSe4. For that reason, Chapter 3 shifts the direction of the Cu3PSe4 synthesis towards a more stoichiometric, atom-economical reaction by eliminating ODE as the solvent. Rather, a long-chain, aliphatic solvent, octadecane (ODA) is employed that proves to be an operationally inert solvent under the standard synthetic conditions and produces cleaner, phase pure Cu3PSe4 NPs as determined by powder X-ray diffraction (PXRD) and transmission electron microscopy (TEM). If ODA was reacting with Se0 powder, the most favorable pathway, commonly cited in literature, is the formation of H2Se and oxidized ODA (alkene). Hence, molecular characterization techniques, nuclear magnetic resonance (NMR, 1H and 13C) and fast-Fourier infrared spectroscopy (FT-IR), were utilized to demonstrate the absence of oxidized ODA species, which is consistent with Se0 preferentially reacting with Cu3P, promoting a more direct reaction pathway. Eliminating the presence of alternate, competing reaction pathways in the ODE synthesis and establishing a near-stoichiometric reaction, allows us to capture the underlying transformation process of Cu3P to Cu3PSe4. From these systematic improvements, we hypothesize that Se0 powder is dispersed in ODA, which promotes a formal eight-electron transfer between Cu3P and 4 Se0. Extracting the synthetic information from the previous chapters to target the metastable Cu-P-Se phase, Cu7PSe6, provides the framework for Chapter 4. Previous methods to isolate Cu7PSe6 are based on traditional, solid-state techniques, where the elemental precursors are ground and subsequently heated to high temperatures (>1000K). Although a colloidal or solution-based synthesis has yet to produce phase-pure Cu7PSe6 particles, attempts explained in Chapter 2 provide a basis on the phase space complexity, where the products consisted of Cu7PSe6 but with thermodynamic byproducts, Cu-Se phases and Cu3PSe4 present. Therefore, an alternate Se precursor, diphenyl diselenide (Ph2Se2), is employed to form the metastable phase, which effectively avoids Cu3PSe4 formation. Importantly, an alternate route to form Cu3PSe4 is with analogous dialkyl diselenide precursor, dibenzyl diselenide, where a key finding is the presence of amorphous phosphorus (P) on Cu1-xSe binaries at low temperatures, which then efficiently reincorporates once the desired 300 ˚C reaction temperature is reached. Thus, in Chapter 4 we investigate why Cu7PSe6 is favored with Ph2Se2 as a precursor, which is predicated on the formation of byproduct species that effectively "trap" P. A proof of concept is explored to further demonstrate the dynamics of P in solution, where the Cu-P-Se phase space can be controllably toggled across by injecting P(5+) species. A drawback for the Cu-P-Se syntheses is the lack of compositional understanding of the pre-synthesized Cu3P NPs, thus further complicating the reaction stoichiometries. Chapter 5 first investigates the previously published synthesis by Liu et al., by thoroughly characterizing the final Cu3P nanoparticles under identical reaction conditions and exploring alternate reaction stoichiometries to reduce the presence of residue precursors. From such, it is determined that the particles substantially deviate from the stoichiometric Cu3P composition, with a Cu:P ratio around 1.5:1.0. Particular focus is also placed on monitoring the degradation of a green phosphorous source, triphenyl phosphite, P(OPh)3. Although triphenyl phosphite (TPOP) has been previously used for transition metal phosphide systems, a lack of systematic investigations leads to questions on the reduction of TPOP en route to forming Cu3P, a formal P(3+) to P(3-) event. Additionally, limited characterization of the final organic byproducts in the original synthesis, begs to question what, if any, byproducts could be contaminating the Cu3P NPs. Therefore, we develop and probe stoichiometric syntheses that isolate phase pure Cu3P NPs to avoid the original 30-fold excess of P. The transformation of hexadecylamine (reductant and ligand) and TPOP were characterized with 1H and 31P NMR to evaluate the role of each en route to forming Cu3P. As this is project is still developing, the necessary future directions are given to systematically approach this problem, with an emphasis on first-step experiments and essential characterization methods to completely grasp the decomposition mechanism of TPOP. Ultimately, this has implications when systematically applying TPOP to alternate transitional metal phosphide NP syntheses, as well as developing more precise Cu-P-Se syntheses. Finally, the work presented herein is summarized in Chapter 6 along with an outlook on the project as a whole. Specifically, future directions and preliminary insight into the underlying reaction pathways and mechanism of Cu3PSe4 formation are explored. Additionally, we explore preliminary data on an analogous material Ag-P-Se, which was plagued for years by the lack of a reproducible Ag-P precursor synthesis that limited our ability to extract the synthetic intuition from the Cu-P-Se system. However, recent literature findings on a potential Ag3P precursor provides promise on synthesizing Ag-P-Se phases in the future, which is critically analyzed to ensure that any bottlenecks in future syntheses are limited. Ultimately, the work provided in the following chapters is aimed at making strides to developing a more in depth understanding of precursor interactions between transition metals and main group elements, as well as properly monitoring such reactions to extract synthetic information to analogous systems. With the knowledge gained on the presented studies, we aspire to contribute to the NP field in order to continually improve NP synthesis and therefore nanomaterials. Finally, this work is supported by NSF Macromolecular, Supramolecular, and Nanochemistry (MSN #2109141).Item Open Access Development of surface modifications on titanium for biomedical applications(Colorado State University. Libraries, 2021) Maia Sabino, Roberta, author; Popat, Ketul C., advisor; Martins, Alessandro F, advisor; Herrera-Alonso, Margarita, committee member; Li, Yan Vivian, committee member; Wang, Zhijie, committee memberFor decades, titanium-based implants have been largely employed for different medical applications due to their excellent mechanical properties, corrosion resistance, and remarkable biocompatibility with many body tissues. However, even titanium-based materials can cause adverse effects which ultimately lead to implant failure and a need for revision surgeries. The major causes for implant failure are thrombus formation, bacterial infection, and poor osseointegration. Therefore, it is essential to develop multifunctional surfaces that can prevent clot formation and microbial infections, as well as better integrate into the body tissue. To address these challenges, two different surface modifications on titanium were investigated in this dissertation. The first one was the fabrication of superhemophobic titania nanotube (NT) surfaces. The second approach was the development of tanfloc-based polyelectrolyte multilayers (PEMs) on NT. The hemocompatibility and the ability of these surfaces to promote cell growth and to prevent bacterial infection were investigated. The results indicate that both surface modifications on titanium enhance blood compatibility, and that tanfloc-based PEMs on NT improve cell proliferation and differentiation, and antibacterial properties, thus being a promising approach for designing biomedical devices.Item Open Access Mechanistically-guided advancement of photoinduced organocatalyzed atom transfer radical polymerization(Colorado State University. Libraries, 2020) Buss, Bonnie Leigh, author; Miyake, Garret, advisor; Bailey, Travis, committee member; Shi, Yian, committee member; Herrera-Alonso, Margarita, committee memberPhotoinduced organocatalyzed atom transfer radical polymerization (O-ATRP) is a promising polymerization methodology which leverages radical reactivity to afford macromolecular products with a high degree of control over polymer molecular weights and molecular weight distributions, paired with the added benefit of spatial and temporal control over polymerization. This process, a metal-free approach, relies on photoexcitation of an organic photoredox catalyst which stringently mediates the radical activation and deactivation steps of an oxidative quenching catalytic cycle. To successfully operate this cycle, and thus control the polymerization, the rate of deactivation must be faster than both the rates of radical activation and monomer propagation. Central to the initial development of O-ATRP has been the design and study of strongly reducing organic photocatalysts, particularly in the context of methacrylate monomer polymerizations. However, as a burgeoning methodology, the full scope of O-ATRP has not yet been established. In this dissertation, efforts in addressing three key challenges in O-ATRP, including reaction scalability, complex architecture synthesis, and polymerization of challenging monomers, through manipulation of features of the oxidative quenching mechanistic cycle is presented. To address these challenges diverse approaches were employed, including adaptation to continuous-flow reactors, implementation of multifunctional initiating systems, and rational design of a new family of organic photocatalysts, ultimately facilitating progression of O-ATRP to a scalable and efficient approach in the well-defined synthesis of industrially-relevant materials.Item Open Access Reductive coupling reactions of organosilanes for the monoselective C–F functionalization of trifluoromethylarenes(Colorado State University. Libraries, 2022) Wright, Shawn E., author; Bandar, Jeffrey, advisor; Paton, Robert, committee member; Borch, Thomas, committee member; Herrera-Alonso, Margarita, committee memberThe mono-selective defluorofunctionalization of trifluoromethylarenes is an emerging strategy to access ⍺,⍺-difluorobenzylic derivatives, which are difficult to access in a divergent manner. Fluorine incorporation is a common strategy employed during the optimization of potential pharmaceuticals in the drug discovery process. Much effort has been spent over the past few decades in developing fluorination methodologies, and the result has been tremendous growth in aryl and alkyl fluorination and trifluoromethylation reactions. On the other hand, methods to install other fluoroalkyl motifs are less developed. Due to the abundant availability of trifluoromethylarenes, mono-selective defluorofunctionalization reactions would be an ideal route to access ⍺,⍺-difluorobenzylic derivatives, which are becoming increasing examined in drug discovery settings. Chapter one will provide the necessary background to understand the context of the work described throughout the following chapters. First, there will be an overview of the importance of fluorine for the development of pharmaceutical compounds. Then there will be a brief summary of the different strategies that have been developed to achieve the trifluoromethylation of arenes as well as the common routes to access ⍺,⍺-difluorobenzylic compounds. Finally, a thorough discussion of the challenges and reported solutions to achieve mono-selective defluorofunctionalization of trifluoromethylarenes will be provided. Chapter two will describe the initial discovery, development, and mechanistic investigation of the defluoroallylation reaction reported by the Bandar group. This discovery led to the identification of a new strategy to achieve reductive coupling through the use of Lewis base activated organosilanes, which provides the basis for the reactions discovered and developed in chapters three and four. Chapter three will describe the discovery, development, and mechanistic investigation of a reductive coupling reaction of trifluoromethylarenes with formamides. This reaction generates a silylated hemiaminal product which is a valuable synthetic intermediate to access a broad scope of ⍺,⍺-difluorobenzylic derivatives. Mechanistic investigations support the generation of a ⍺,⍺-difluorobenzylsilane intermediate in the reaction. Isolated of the ⍺,⍺-difluorobenzylsilane and subsequent derivatizations further broaden the scope of transformations accessible via this reductive coupling process. Chapter four will describe the discovery and preliminary development of the mono-selective hydrodefluorination of trifluoromethylarenes using hydrosilanes activated by a Lewis basic catalyst. Two different catalytic systems are demonstrated that operate via different mechanisms, which provides access to different reaction scopes. A short discussion on the future work of this project will also be provided, where a junior graduate student is developing conditions to enable the mono-selective hydrodefluorination of electron-neutral trifluoromethylarenes.Item Open Access Sustainable polymer synthesis through the design of organic photoredox catalysts and development of poly(norbornane trithiolanes)(Colorado State University. Libraries, 2023) Price, Mariel Jene, author; Miyake, Garret, advisor; Paton, Robert, committee member; Zadrozny, Joseph, committee member; Herrera-Alonso, Margarita, committee memberThere are many avenues through which the sustainability synthesis, use, and disposal of polymeric materials can be approached. One of the two approaches explored in this work is the sustainable design and use of polymerization catalysts. Proper employment of catalysis can greatly decrease the energy input required to synthesize polymers and intentional design of those catalysts can enable their use in small quantities without compromising their effectiveness or the sustainability with which they are made and used. Herein, the development of a new class of metal-free photoredox catalysts (made from abundant elements) which can use visible wavelengths of light (a readily available, replenishable, and mild source of energy) to control the polymerization acrylate monomers is reported. Through this work we provide insight into how catalyst structure can be tuned to achieve desired properties and what properties might render certain catalysts more effective at lower loadings. The second approach explored herein towards improving the sustainability of polymer synthesis, use, and disposal is related to the recyclability of the polymeric materials. In addition to sustainable synthesis through catalysis, one way to improve the sustainability of polymeric materials is to increase their viable economic lifetime. Polymeric materials that are readily recyclable prevent the loss of materials through disposal. In the work reported herein methods for the synthesis and polymerization of sulfur-containing monomers to generate polymeric materials with intrinsic recyclability are investigated, approaches for efficient depolymerization of such polymers improved, and the scope of these materials expanded.Item Embargo Thermally-assisted frontal polymerization for rapid curing of fiber-reinforced polymer composites(Colorado State University. Libraries, 2024) Naseri, Iman, author; James, Susan, advisor; Bailey, Travis, committee member; Herrera-Alonso, Margarita, committee member; Ma, Kaka, committee memberFiber-reinforced polymer composites (FRPCs) are widely used in a variety of applications owing to their excellent specific mechanical properties, chemical stability, and fatigue resistance. However, the state-of-the-art technologies for manufacturing FRPCs are intensive in terms of time and energy, generate a significant carbon footprint, and require costly resources. In addition, FRPCs lack key non-structural functionalities (e.g., de-icing, damage sensing) required for many applications. Despite the enormous efforts made to improve the manufacturability of FRPCs and address the shortcomings associated with the performance of FRPCs, there is still a pressing need for alternative manufacturing technologies to enable the rapid, energy-efficient, and low-cost manufacturing of multifunctional fiber-reinforced polymer composites. In this dissertation, a novel technique for rapid and cost-effective manufacturing of multifunctional fiber-reinforced polymer composites is developed by exploiting the frontal polymerization concept and joule heating of nanostructured materials. A nanostructured paper or fabric is integrated into the composite layup to supply the energy required to trigger frontal polymerization via the Joule heating effect. In addition, the nanostructured paper remains advantageous in in-service conditions and imparts new functionalities to the host composite structure. In the first chapter, the recent developments in material systems, as well as heating techniques reported for improving the manufacturability of FRPCs, are reviewed, and frontal polymerization (FP) as a rapid and energy-efficient technique for curing thermoset matrix composites is introduced. In the second chapter, frontal curing of multifunctional composites via a commercial nanostructured heater (buckypaper) is demonstrated, and the curing behavior of composite laminate is studied under various layup conditions. It is demonstrated that the through-thickness FP manufacturing strategy using an embedded buckypaper surface heater allows for rapid and energy-efficient manufacturing of fully cured composite panels using the conventional tooling materials utilized in the composite industry. However, the temperature profiles developed during the cure cycle, as well as the degree of cure of resin in produced composites, are greatly affected by the thermal properties of the tooling materials, where lower front temperatures and degree of cure are measured for composite panels manufactured using thermally conductive tooling materials such as aluminum. This issue can be effectively addressed by preheating the dry composite layup for a few minutes. Despite the relatively uniform heat generation in nanostructured buckypaper heaters, the infrared thermal imaging of the curing process reveals that the front initiates from multiple locations and propagates in both the through-thickness and in-plane directions. In addition, the de-icing functionality is demonstrated in the cured composite as one of the several possible functionalities imparted to composite structures due to the presence of a buckypaper layer. In the third chapter, a fabric heater is developed by writing laser-induced graphene on aramid fabric using a CO2 laser and used as an integrated heater for manufacturing FRPCs via the through-thickness FP manufacturing technique. A 10 cm × 10 cm composite panel is successfully cured within only 1 minute with a total energy consumption of 4.13 KJ, which is comparable to the time and energy required for producing a similar composite panel using a buckypaper heater. In addition to composite manufacturing, flexible heaters are prepared with the addition of silicone rubber to fabric heaters. Although the addition of electrically insulating rubber negatively affects the electrothermal performance of fabric heaters, it greatly improves the durability of fabric heaters. In the fourth chapter, a facile and rapid technique for the preparation of mechanically robust nanocomposite film heaters is developed based on a frontally polymerizable resin system. The mechanical and electrothermal properties of the nanocomposite film heaters are characterized, and the produced heaters are used for out-of-oven manufacturing composite laminates. In the final chapter, the main research findings are summarized, and the recommendations for future studies are presented.Item Open Access Understanding selectivity in organic reactions through density functional theory(Colorado State University. Libraries, 2024) de Lescure, Louis Raymond Philibert, author; Paton, Robert, advisor; McNally, Andrew, advisor; Bandar, Jeffrey, committee member; Kennan, Alan, committee member; Herrera-Alonso, Margarita, committee memberThe success of chemical reactions is often expressed through the lens of selectivity, defined as the preference for a desired reaction pathway over an undesirable one. A profound understanding of the rationale behind the selectivity of chemical reactions is crucial for the progression of synthetic methodologies in organic chemistry. Utilizing quantum chemical approximations, density functional theory (DFT) calculations offer unparalleled insights into the electronic structures and mechanisms of reactions, which can be correlated with observed empirical selectivities. This dissertation demonstrates the significant utility of DFT, in tandem with experimental evidence, in elucidating the intricate mechanisms of reactions. Chapter 1 defines the thematic and methods used throughout this thesis. Chapters 2 and 3 detail collaborative work with the McNally group at Colorado State University. Here, we developed innovative methods for the halogenation of pyridines and advanced modifications of pyrimidine rings utilizing redesigned Zincke chemistry. This chapter focuses on the factors influencing the regioselectivity of halogenation processes and provides mechanistic insights into the formation of crucial intermediates. Chapter 3 outlines a joint project with the Race group at the University of Minnesota, where we explored the homologation of benzylic carbon-bromide bonds. Our investigations centered on the ring-opening of phenonium intermediates, a critical step in determining the success of the reaction. Chapter 4 presents a collaboration with the Aggarwal group at the University of Bristol. This chapter examines the nuanced interplay between kinetic and thermodynamic factors that govern the enantioselectivity of the reaction discussed. This comprehensive study underscores the integration of theoretical and experimental approaches in advancing our understanding of complex chemical reactions.