Matching Items (25)
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Description
In the search for ever more sustainable manufacturing techniques, additive manufacturing through light driven 3D printing processes is growing rapidly as a field, specifically the production of “living” materials which can be repaired and or reprocessed through the reactivation of polymer chain ends. Currently research in the production of these

In the search for ever more sustainable manufacturing techniques, additive manufacturing through light driven 3D printing processes is growing rapidly as a field, specifically the production of “living” materials which can be repaired and or reprocessed through the reactivation of polymer chain ends. Currently research in the production of these living materials is largely focused on radical polymerization methods. Cationic polymerizations have been developed for this purpose, although there is still much work to be done. This work seeks to explore a transition-metal free system to produce living materials through cationic reversible addition fragmentation chain-transfer (C-RAFT).Cationic polymerization is known for its rapid propagation. This is due to the highly reactive active center which also readily reacts with nucleophiles in unwanted chain transfer reactions. For this reason, reagents in living cationic polymerizations are subject to rigorous purification steps involving the distillation of monomer and solvent, freeze—pump—thaw cycles, and running the reaction under an inert environment1. These restrictions make living cationic polymerizations unattractive for 3D printing processes. New systems for rapid water tolerant C-RAFT photopolymerization will provide for new materials to be produced through this more sustainable manufacturing process. In this work, living cationic polymerization of isobutyl vinyl ether (IBVE) is achieved using a synthesized cationic RAFT agent and an initiating system consisting of camphorquinone (CQ), ethyl 4-(dimethylamino)benzoate, and iodonium salt HNu-254. Molecular weights of 12 kg/mol are achieved with a dispersity of 1.4. The polymerization mechanism is probed and shows rapid kinetics consistent with living polymerizations in addition to photo-controllability as indicated by light on-off experiments. Chain extension experiments display re-activation of the trithiocarbonate chain end. This feature is then used to produce block-copolymers using ethyl vinyl ether and cyclohexyl vinyl ether.
ContributorsHawkins, Kade Denver (Author) / Seo, Eileen (Thesis advisor) / Long, Timothy (Committee member) / Jin, Kailong (Committee member) / Arizona State University (Publisher)
Created2023
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Description
With increasing advance complexity in the structure to be 3D printed, the use of post processing removal of support structures has become more complicated thing due to the need of newer tool case to remove supports in such scenarios. Attempts have been made to study, research and experiment the dissolvable

With increasing advance complexity in the structure to be 3D printed, the use of post processing removal of support structures has become more complicated thing due to the need of newer tool case to remove supports in such scenarios. Attempts have been made to study, research and experiment the dissolvable and recyclable photo-initiated polymeric resin that can be used to build support structure. Vat photo-polymerization method of manufacturing was selected due to wide range of materials that can be selected and researched which can have the potential to be selected further for large scale manufacturing. Deep understanding of the recyclable polymer was done by performing chemical and mechanical property test. Varying light intensities are used to study the curing properties and respective dissolving properties. In this thesis document, recyclable and dissolvable polymeric resin have been selected to print the support structures which can be later dissolved and recycled.The resin was exposed to varying light projections using grayscales of 255, 200 and 150 showing different dissolving time of each structure. Dissolving time of the printed parts were studied by varying the surface to volume ratios of the part. Higher the surface to volume ratios of the printed part resulted in lower time it takes to dissolve the part in the dissolving solution. The mechanical strengths of the recycled part were found to be pretty solid as compared to the freshly prepared resin, good sign of using it for multiple times without degrading its strength. Cactus shaped model was printed using commercial red resin and supports with the recyclable solution to deeply understand the working and dissolving properties of recyclable resin. Without any external efforts, the supports were easily dissolved in the solution, leaving the cactus intact. Further work is carried on printing Meta shaped gyroid lattice structure in effort to lower the dissolving time of the supports while maintaining enough mechanical stress. Future efforts will be made to conduct the rheology test and further lower the dissolving time as much it can to be ready for the commercial large scale applications.
ContributorsNawab, Prem Kalpesh (Author) / Li, Xiangjia (Thesis advisor) / Zhuang, Houlong (Committee member) / Jin, Kailong (Committee member) / Arizona State University (Publisher)
Created2023
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Description
High-performance polymers (HPPs) have dominated the synthetic polymer market for critical applications, including aerospace, energy, microelectronic, and transportation industries since their development in the mid-1900s. Although their structures share general similarities, such as high aromatic content, HPPs offer wide structural variance providing amorphous and semi-crystalline systems. As a result, conventional

High-performance polymers (HPPs) have dominated the synthetic polymer market for critical applications, including aerospace, energy, microelectronic, and transportation industries since their development in the mid-1900s. Although their structures share general similarities, such as high aromatic content, HPPs offer wide structural variance providing amorphous and semi-crystalline systems. As a result, conventional processing methods employed for HPPs are energy intensive and accessible part geometry is limited; often requiring subsequent subtractive techniques, i.e.,; milling, to obtain high quality and performant parts. Traditional processes were challenged by the emergence of advanced manufacturing techniques, such as 3D printing, which spurred significant academic and industrial interest. In the first project, poly(arylene ether sulfone)s (PSU) were chemically modified post-polymerization to enable ensuing photopolymerization of high molecular weight (Mn) PSU solutions into complex shapes with vat photopolymerization (VP). The resulting materials exhibited fast crosslinking, but low and unstable plateau storage moduli (G’). To overcome this, addition of low molecular weight crosslinker and precise control of UV irradiation increased crosslink density and inhibited photodegradation events, respectively. Ultimately, these modifications facilitated the first report of PSU structures fabricated with a UV-assisted AM modality. Next, 3D printable polyimides (PIs) were synthesized and extensively characterized to further expand the HPP AM toolbox. However, fully aromatic PIs pose a significant challenge as most are insoluble, intractable, and lack any discernable viscous flow. AM PIs were produced using two distinct approaches previously reported in the Long research group; the pendant salt approach imparts photoreactivity through the neutralization of the poly(amic acid) intermediate with small molecule amino-acrylates while the polysalt approach employs dicarboxylate-diammonium ionic organization to template the PI amongst an acrylic scaffold. Through the pendant salt approach, water soluble PI precursors enabled facile AM of complex structures, which served as efficient carbon precursors. The polysalt approach offers superior solid content and solution viscosities; however, these highly polar solutions initially exhibited deleterious side reactions. Application of acid-base fundamentals provided novel printable polysalt solutions with extended shelf-life, reproducible printing, and simplified processing. The relationships established from these projects expanded the applications of the most performant synthetic polymers and will inform future polymer design for additive manufacturing.
ContributorsWeyhrich, Cody (Author) / Long, Timothy E (Thesis advisor) / Williams, Christopher B (Committee member) / Biegasiewicz, Kyle F (Committee member) / Jin, Kailong (Committee member) / Arizona State University (Publisher)
Created2023
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Description
Additive manufacturing, also known as 3D printing, has revolutionized modern manufacturing in several key areas: complex geometry fabrication, rapid prototyping and iteration, customization and personalization, reduced material waste, supply chain flexibility, complex assemblies and consolidated parts, and material innovation. As the technology continues to evolve, its impact on manufacturing is

Additive manufacturing, also known as 3D printing, has revolutionized modern manufacturing in several key areas: complex geometry fabrication, rapid prototyping and iteration, customization and personalization, reduced material waste, supply chain flexibility, complex assemblies and consolidated parts, and material innovation. As the technology continues to evolve, its impact on manufacturing is expected to grow, driving further innovation and reshaping traditional production processes. Some innovation examples in this field are inspired by natural or bio-systems, such as honeycomb structures for internal morphological control to increase strength, bio-mimetic composites for scaffold structures, or shape memory materials in 4D printing for targeted drug delivery. However, the technology is limited by its ability to manipulate multiple materials, especially tuning their submicron characteristics when they show non-compatible chemical or physical features. For example, the deposition and patterning of nanoparticles with different dimensions have seen little success, except in highly precise and slow 3D printing processes like aerojet or electrohydrodynamic. Taking inspiration from the layered patterns and structures found in nature, this research aims to demonstrate the development and versatility of a newly developed ink-based composite 3D printing mechanism called multiphase direct ink writing (MDIW). The MDIW is a multi-materials extrusion system, with a unique nozzle design that can accommodate two immiscible and non-compatible polymer or nano-composite solutions as feedstock. The intricate internal structure of the nozzle enables the rearrangement of the feedstock in alternating layers (i.e., ABAB...) and multiplied within each printed line. This research will first highlight the design and development of the MDIW 3D printing mechanism, followed by laminate processing to establish the requirements of layer formation in the XY-axis and the effect of layer formation on its microstructural and mechanical properties. Next, the versatility of the mechanism is also shown through the one-step fabrication of shape memory polymers with dual stimuli responsiveness, highlighting the 4D printing capabilities. Moreover, the MDIW's capability of dual nanoparticle patterning for manufacturing multi-functional carbon-carbon composites will be highlighted. Comprehensive and in-depth studies are conducted to investigate the morphology-structure-property relationships, demonstrating potential applications in structural engineering, smart and intelligent devices, miniature robotics, and high-temperature systems.
ContributorsRavichandran, Dharneedar (Author) / Nian, Qiong (Thesis advisor) / Song, Kenan (Committee member) / Green, Matthew (Committee member) / Jin, Kailong (Committee member) / Bhate, Dhruv (Committee member) / Arizona State University (Publisher)
Created2024
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Description
The excessive use of fossil fuels over the last few centuries has led to unprecedented changes in climate and a steady increase in the average surface global temperatures. Direct Air Capture(DAC) aims to capture CO2 directly from the atmosphere and alleviate some of the adverse effects of climate change. This

The excessive use of fossil fuels over the last few centuries has led to unprecedented changes in climate and a steady increase in the average surface global temperatures. Direct Air Capture(DAC) aims to capture CO2 directly from the atmosphere and alleviate some of the adverse effects of climate change. This dissertation focuses on methodologies to make advanced functional materials that show good potential to be used as DAC sorbents. Details on sorbent material synthesis and post-synthesis methods to obtain high surface area morphologies are described in detail. First, by incorporating K2CO3 into activated carbon (AC) fiber felts, the sorption kinetics was significantly improved by increasing the surface area of K2CO3 in contact with air. The AC-K2CO3 fiber composite felts are flexible, cheap, easy to manufacture, chemically stable, and show excellent DAC capacity and (de)sorption rates, with stable performance up to ten cycles. The best composite felts collected an average of 478 µmol of CO2 per gram of composite during 4 h of exposure to ambient (24% RH) air that had a CO2 concentration of 400-450 ppm over 10 cycles. Secondly, incorporating the amino acid L-arginine (L-Arg) into a poly(vinyl alcohol) (PVA) nanofiber support structure, created porous substrates with very high surface areas of L-Arg available for CO2 sorption. The bio-inspired PVA-Arg nanofiber composites are flexible and show excellent DAC performance compared to bulk L-Arg. The nanofiber composites are fabricated from an electrospinning process using an aqueous polymer solution. High ambient humidity levels improve sorption performance significantly. The best performing nanofiber composite collected 542 µmol of CO2 per gram of composite during 2 h of exposure to ambient, high humidity (100% RH) air that had a CO2 concentration of 400-450 ppm. Finally, poly(vinyl guanidine) (PVG) polymer was synthesized and tested for sorption performance. The fabrication of PVG nanofibers, divinyl benzene crosslinked PVG beads and glutaraldehyde crosslinked PVG were demonstrated. The sorption performance of the fabricated sorbents were tested with the glutaraldehyde crosslinked PVG having a dynamic sorption capacity of over 1 mmol of CO2 per gram of polymer in 3 h. The sorption capability of liquid PVG was also explored.
ContributorsModayil Korah, Mani (Author) / Green, Matthew D (Thesis advisor) / Lackner, Klaus (Committee member) / Long, Timothy E (Committee member) / Thomas, Marylaura L (Committee member) / Jin, Kailong (Committee member) / Arizona State University (Publisher)
Created2024
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Description
Creating 3D objects out of high performance polymers, such as polyimides, is notoriously difficult since the highly stable polymer backbone limits processibility without extreme conditions. However, designing the polyimide precursor to crosslink upon photoirradiation enables the additive manufacturing of polyimides into complex, 3D objects. Crosslinking the photoactive polyimide precursor forms

Creating 3D objects out of high performance polymers, such as polyimides, is notoriously difficult since the highly stable polymer backbone limits processibility without extreme conditions. However, designing the polyimide precursor to crosslink upon photoirradiation enables the additive manufacturing of polyimides into complex, 3D objects. Crosslinking the photoactive polyimide precursor forms a solid 3D organogel, then subsequent thermal treatment removes the sacrificial scaffold and simultaneously imidizes the precursor into a 3D polyimide. The collaborative efforts of the Long and Williams group at Virginia Tech created three chemically distinct photoactive polyimide precursors to additively manufacture 3D polyimide objects for aerospace applications and to maintain the nuclear stockpile. The first chapter of this dissertation introduces fully aromatic polyimides and the additive manufacturing techniques used to print photoactive polyimide precursors. The second chapter reviews the common pore forming methods typically utilized to develop porous polyimides for low dielectric applications. The following chapters investigate the impact of the sacrificial scaffold on the thermo-oxidative aging behavior of the polyimide precursors after imidization, then focuses on lowering the imidization temperature of the polyimide precursor using base catalysis. These investigations lead to the creation of photoactive polysalts with polyethylene glycol (PEG) side chains to develop 3D, porous polyimides with tunable morphologies. Varying the molecular weight and concentration of the PEG side chains along the backbone tuned the pore size, and the photoactive nature of the polyimide precursor enabled 3D, porous polyimides printed using digital light processing.
ContributorsVandenbrande, Johanna (Author) / Long, Timothy E (Thesis advisor) / Williams, Christopher B (Committee member) / Jin, Kailong (Committee member) / Seo, Eileen (Committee member) / Arizona State University (Publisher)
Created2023
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Description

My thesis, Design of Hierarchically Porous Materials Containing Covalent Organic Frameworks, focuses on testing the validity of incorporating nanoporous organic materials into macroporous scaffolding to improve the functionality of covalent organic frameworks as materials for filtration applications. The macroporous scaffold was based off of a material recently described in literature

My thesis, Design of Hierarchically Porous Materials Containing Covalent Organic Frameworks, focuses on testing the validity of incorporating nanoporous organic materials into macroporous scaffolding to improve the functionality of covalent organic frameworks as materials for filtration applications. The macroporous scaffold was based off of a material recently described in literature and the bulk of the experimentation was focused on the effects of the necessary processing for the creation of the macroporous material on the structure of the covalent organic frameworks. The property primarily investigated was the Brunauer-Emmett-Teller surface area, as the applicability of the frameworks is largely determined by their nanoporous surface area.

ContributorsRidenour, Brian (Author) / Jin, Kailong (Thesis director) / Tongay, Sefaattin (Committee member) / Barrett, The Honors College (Contributor) / Materials Science and Engineering Program (Contributor)
Created2023-05
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Description
Upon cooling a semicrystalline polymer from its amorphous melt state, it undergoes melt crystallization where organized microstructures develop through a process of nucleation and crystal growth. Understanding the crystallization kinetics of a semicrystalline thermoplastic is key to tuning crystallinity and microstructure, which play integral roles in the material’s final properties

Upon cooling a semicrystalline polymer from its amorphous melt state, it undergoes melt crystallization where organized microstructures develop through a process of nucleation and crystal growth. Understanding the crystallization kinetics of a semicrystalline thermoplastic is key to tuning crystallinity and microstructure, which play integral roles in the material’s final properties such as toughness, gas permeability, and degradation rate. Nonisothermal crystallization, in particular, has great technological relevance to polymer engineering processes such as injection molding, film blowing, and fiber spinning, all of which rely on fast cooling rates. Spectroscopic, scattering, calorimetric, and rheological techniques have been conventionally used for studying nonisothermal crystallization, but can be limited in their sensitivity, tunability, and availability. Our group has recently developed a fluorescence technique for sensing the melting transitions of semicrystalline thermoplastics by incorporating fluorescent probes into polymer matrices. Herein, this methodology has been extended to an in-situ study of nonisothermal melt crystallization by monitoring the T-dependent fluorescence intensity of the fluorophores incorporated into a polymer matrix. As crystals form upon cooling from the amorphous melt state, the intramolecular motions of fluorophores are restricted and thus their T-dependent fluorescence intensity data exhibit a stepwise increase during nonisothermal crystallization. The first derivative of the T-dependent fluorescence intensity data can provide insight into the onset, peak, and endset crystallization temperatures, all of which align reasonably well with conventional differential scanning calorimetry measurements. This facile, sensitive, and contact-free fluorescence technique can access faster cooling rates (up to ~100 oC min-1) than many other existing methods for nonisothermal crystallization studies, which is more relevant to industrial polymer processing conditions. Additionally, the fluorescence detection mechanism shows great sensitivity not only to the degree of crystallinity but also to the crystalline microstructure formed during nonisothermal crystallization. Furthermore, unique fluorescent labeling is expected to foster novel studies on the local crystallization within heterogeneous polymeric systems including blends, composites, and multilayer films. Such local crystallization studies are out of reach for most conventional techniques that measure spatially averaged properties. Overall, this nonisothermal crystallization study expands the capabilities of this novel fluorescence technique for advancing the field of semicrystalline thermoplastic design and processing.
ContributorsCabello, Maya (Author) / Jin, Kailong (Thesis director) / Nile, Gabriel (Committee member) / Barrett, The Honors College (Contributor) / Chemical Engineering Program (Contributor)
Created2022-05
Description

Using DFT calculations and GAMESS computational software, porphine and its derivatives were analyzed for unique sites to accept the adsorbates As(III), As(V) and P(V) in order to compare resulting adsorption energies and determine if any of these molecules prefer arsenic oxyanions over phosphate. Pure porphine preferred As(III) over P(V) with

Using DFT calculations and GAMESS computational software, porphine and its derivatives were analyzed for unique sites to accept the adsorbates As(III), As(V) and P(V) in order to compare resulting adsorption energies and determine if any of these molecules prefer arsenic oxyanions over phosphate. Pure porphine preferred As(III) over P(V) with a resulting adsorption energy of -0.7974 eV. Of the functionalized porphyrins tested, carboxyl porphyrin preferred As(V) over P(V) with a total adsorption energy of -0.7345 eV. Ethyl, methyl, chlorine and amino porphyrin all preferred As(III), with energies of -0.7934, -0.8239, -0.7602, and -0.8508 eV, respectively. Of the metalated porphyrins tested, copper and vanadium porphyrin preferred As(V) over P(V) with adsorption energies of -0.7645 and -2.0915 eV. Chromium, iron and magnesium porphyrin all preferred As(III) over P(V) with energies of -0.5993, -1.4539, and - 1.0790 eV, respectively.

ContributorsKusbel, Ashley (Author) / Muhich, Christopher (Thesis director) / Jin, Kailong (Committee member) / Barrett, The Honors College (Contributor) / Chemical Engineering Program (Contributor)
Created2023-05
Description

Plastic consumption has reached astronomical amounts. The issue is the single-use plastics that continue to harm the environment, degrading into microplastics that find their way into our environment. Finding sustainable, reliable, and safe methods to break down plastics is a complex but valuable endeavor. This research aims to assess the

Plastic consumption has reached astronomical amounts. The issue is the single-use plastics that continue to harm the environment, degrading into microplastics that find their way into our environment. Finding sustainable, reliable, and safe methods to break down plastics is a complex but valuable endeavor. This research aims to assess the viability of using biochar as a catalyst to break down polyethylene terephthalate (PET) plastics under hydrothermal liquefaction conditions. PET is most commonly found in single-use plastic water bottles. Using glycolysis as the reaction, biochar is added and assessed based on yield and time duration of the reaction. This research suggests that temperatures of 300℃ and relatively short experimental times were enough to see the complete conversion of PET through glycolysis. Further research is necessary to determine the effectiveness of biochar as a catalyst and the potential of process industrialization to begin reducing plastic overflow.

ContributorsWyatt, Olivia (Author) / Deng, Shuguang (Thesis director) / Jin, Kailong (Committee member) / Barrett, The Honors College (Contributor) / Chemical Engineering Program (Contributor)
Created2023-05