This dissertation investigates the pressing issue of climate change, identifying carbon dioxide as its main driver and introduces Direct Air Capture (DAC) as a crucial technology for achieving significant reductions in net global emissions. Through an extensive review of existing literature on DAC, it examines various methods and materials developed for this purpose, highlighting the ongoing efforts, advancements, and potential for real-world application. A novel sorbent, quaternary ammonium-functionalized poly(arylene ether sulfone) is explored for DAC via the moisture swing process. This sorbent exhibited the ability to capture and release atmospheric CO2 by a swing in moisture. Effects of form factors of powder, free standing dense membrane and thin film composite membrane were also evaluated for DAC. Furthermore, the dissertation explores modifications to poly(arylene ether sulfones) – polymers primarily used in desalination processes – to enhance water scarcity solutions by improving desalination membrane hydrophilicity and reducing fouling. This enhancement is achieved through the incorporation of zwitterionic groups into the polymer structure. Additionally, it investigates the synthesis of polysulfone polymers from lignin-derivable monomers, offering a greener alternative to traditional polysulfones used in desalination due to their environmental and health concerns. Polysulfones derivable from lignin exhibited comparable thermal properties and enhanced hydrophilicity compared to petroleum-derived polymers, showing considerable promise. Lastly, this dissertation investigates a potential hybrid system for desalination and direct ocean capture by integrating redox-active compounds into desalination membranes. This aims to achieve a pH swing that facilitates the formation of dissolved CO2.

Global emissions of carbon dioxide are reaching new heights every year since the Industrial Revolution. A major contributor to this is fossil fuel consumption. The consumption trend has indicated all this. It has also strengthened the argument for the need to cut down emissions and sweep out historical emissions through the implementation of Carbon Capture, Utilization, and Storage (CCUS) and Carbon Dioxide Removal (CDR) technologies respectively. This is required to control global warming. Direct Air Capture (DAC) is one of the CDR technologies. Extensive research and projections have suggested that DAC has tremendous potential to achieve global climate change mitigation goals. The feasibility of DAC is proven but work is required to bridge gaps in DAC research to make it affordable and scalable. Process modelling is an approach used to address these concerns. Current DAC research in system design and modelling is discrete and existing models have limited use cases. This work is focused on the development of a generalized process mass transfer model for the capture stage of solid sorbent DAC contactors. It provides flexibility for defining contactor geometry, selection of ambient conditions, and versatility to plug different sorbents in it for CO2 capture. The modelling procedure is explained, and a robustness check is performed to ensure model integrity. The results of the robustness check and sensitivity analysis are then explained. This research is part of a long-term effort to create a complete modelling package for the DAC community to boost research and development to large-scale deployments.

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.

Freshwater is becoming more and more scarce, and the need to make use of other water resources is critical. Although processes such as Sea Water Reverse Osmosis (SWRO) exist, these processes are not without drawbacks, such as a brine with a high salt concentration being a byproduct of SWRO. Pervaporation is a potential solution to this problem, however the membranes used in these processes are prone to fouling and the high salt conditions are difficult to work around. Incorporating zwitterions into the polymeric backbone of these membranes has proven to be an effective way to increase fouling resistance. In this work, sulfobetaine – based zwitterions were incorporated into the backbone of poly(arylene ether sulfone) to synthesize sulfobetaine – modified poly(arylene ether sulfone) (SB-PAES) membranes, which were then tested in a cross-flow pervaporation apparatus to analyze salt rejection. SB-PAES membranes were cast with two different methods to create a consistent casting protocol. It was determined that casting solutions with a lower weight percent in petri dishes was optimal, but still needs more exploration. The SB-PAES membranes were tested with feed solutions of pure water and salt solutions with concentrations of 1 g/L, 5 g/L, and 10 g/L. Both 50% and 25% charge SB-PAES membranes were tested. The 50% charge membranes showed good flux and salt rejection over 99.9% for a 10 g/L feed solution, while the 25% charge membranes showed less flux and salt rejection around 85% for a feed solution of 10 g/L.

CO2 capture from ambient air (often referred to as direct air capture or DAC) is one of the Carbon Dioxide Removal methodologies that may limit Global Warming. High energy demand and high cost are currently serious barriers for large-scale DAC deployments. Moisture-controlled CO2 sorption is a novel technology for DAC, where CO2 sorption cycles are driven solely by changes in surrounding humidity. In contrast to traditional temperature-swing adsorption cycles, water is a cheaper source of exergy than high-grade heat or electricity and moisture-controlled CO2 sorption may reduce the cost of DAC. However, analytic models that describe this sorption system have not been well established, especially in a quantitative manner. In this dissertation the author first establishes both static and kinetic models analytically with bottom-up approaches from the governing equations. These models are of scientific interest and also of industrial importance. They were validated by literature data and custom experiments. In a second part of the dissertation, the author explores the application of moisture-controlled materials in the form of membranes that actively pump CO2 against a concentration gradient. These explorations are guided by the quantitative models developed in the first part of the dissertation. In CO2 separation technologies relying on actively pumping membranes, a moisture-controlled CO2 sorbent is used as either a gas-gas membrane contactor or a gas-liquid membrane contactor. The author experimentally and theoretically determined that a specific commercial anion exchange membrane that was considered a plausible candidate does not satisfy the requirements for such an active membrane as a consequence of its slow kinetics of carbon transport. Requirements for materials to serve as active membranes have been clarified, which is of great interest for industrial application and will provide a starting point for future material design and development.

The natural healing process for bone has multiple signaling cascades where several soluble factors are expressed at specific times to encourage regeneration. Human mesenchymal stromal cells (hMSCs) have three stages of osteogenic differentiation: an increase in cell number (day 1-4), early cell differentiation showing alkaline phosphatase (ALP) expression (day 5-14), and deposition of calcium and phosphate (day 14-28). The first two stages are of particular interest since cell adhesion peptides have been shown to have biological significance during these early stages of bone regeneration. However, far less is known about the temporal dependence of these signals. To mimic these complex systems, developing dynamic biomaterials has become a popular research area over the past decade. Advances in chemistry, materials science, and manufacturing have enabled the development of complex biomaterials that can mimic dynamic cues in the extracellular matrix. One specific area of interest is spatiotemporal control of multiple biomolecules; however, this has generally required diverse chemical approaches making the process difficult and impractical. To circumvent these issues, I developed a novel method that combines a photoresponsive hydrogel with single-stranded DNA to spatiotemporally control multiple biomolecules using a single conjugation scheme. Here, I describe a detailed protocol to manufacture a fully reversible, spatiotemporal platform using DNA handles. Norbornene-modified hyaluronic acid hydrogels were used to spatially control biomolecule presentation while single-stranded DNA was used to temporally control biomolecule presentation via toehold-mediated strand displacement. This platform was used to orthogonally control the presentation of multiple biomolecules with simple and complex spatial patterning, as well as control the cell morphology of hMSCs by tuning the presentation of the cell adhesion peptide RGDS. Then, this system was applied to study the temporal presentation of cell adhesion peptides and their effect on early osteogenic differentiation of hMSCs in vitro. The peptides used were RGDS, HAVDI, and OGP. OGP alone expressed higher ALP when presented from day 7-14 than day 0-7 or 0-14. When RGDS, HAVDI, and OGP were combined, there was an increase in ALP activity when HAVDI was presented from day 0-3 indicating that HAVDI plays an important role at earlier time points during osteogenic differentiation.

Soft thermal interface materials (TIMs) are critical for improving the thermal management of advanced microelectronic devices. Despite containing high thermal conductivity filler materials, TIM performance is limited by thermal resistances between fillers, filler-matrix, and external contact resistance. Recently, room-temperature liquid metals (LMs) started to be adapted as an alternative TIM for their low thermal resistance and fluidic nature. However, LM-based TIMs face challenges due to their low viscosity, non-wetting qualities, chemical reactivity, and corrosiveness towards aluminum.To address these concerns, this dissertation research investigates fundamental LM properties and assesses their utility for developing multiphase LM composites with strong thermal properties. Augmentation of LM with gallium oxide and air capsules lead to LM-base foams with improved spreading and patterning. Gallium oxides are responsible for stabilizing LM foam structures which is observed through electron microscopy, revealing a temporal evolution of air voids after shear mixing in air. The presence of air bubbles and oxide fragments in LM decreases thermal conductivity while increasing its viscosity as the shear mixing time is prolonged. An overall mechanism for foam generation in LM is presented in two stages: 1) oxide fragment accumulation and 2) air bubble entrapment and propagation. To avoid the low thermal conductivity air content, mixing of non-reactive particles of tungsten or silicon carbide (SiC) into LM forms paste-like LM-based mixtures that exhibit tunable high thermal conductivity 2-3 times beyond the matrix material. These filler materials remain chemically stable and do not react with LM over time while suspended. Gallium oxide-mediated wetting mechanisms for these non-wetting fillers are elucidated in oxygen rich and deficient environments. Three-phase composites consisting of LM and Ag-coated SiC fillers dispersed in a noncuring silicone oil matrix address LM-corrosion related issues. Ag-coated SiC particles enable improved wetting of the LM, and the results show that applied pressure is necessary for bridging of these LM-coated particles to improve filler thermal resistance. Compositional tuning between the fillers leads to thermal improvements in this multiphase composite. The results of this dissertation work aim to advance our current understanding of LMs and how to design LM-based composite materials for improved TIMs and other soft thermal applications.

Metal-organic frameworks have made a feature in the cutting-edge technology with a wide variety of applications because they are the new material candidate as adsorbent or membrane with high surface area, various pore sizes, and highly tunable framework functionality properties. The emergence of two-dimensional (2D) metal-organic frameworks has surged an outburst of intense research to understand the feasible synthesis and exciting material properties of these class of materials. Despite their potential, studies to date show that it is extremely challenging to synthesize and manufacture 2D MOF at large scales with ultimate control over crystallinity and thickness.

The field of research to date has produced various synthesis routes which can further be used to design 2D materials with a range of organic ligands and metal linkers. This thesis seeks to extend these design rules to demonstrate the competitive growth of two- dimensional (2D) metal-organic frameworks(MOF) and their alloys to predict which ligands and metals can be combined, study the intercalation of Bromine in these frameworks and their alloys which leads to the discovery of reduced band gap in the layered MOF alloy.

In this study it has been shown that the key factor in achieving layered 2D MOFs and it relies on the use of carefully engineered ligands to terminate the out-of-plane sites on metal clusters thereby eliminating strong interlayer hydrogen bond formation.

The major contribution of pyridine is to replace interlayer hydrogen bonding or other weak chemical bonds. Overall results establish an entirely new synthesis method for producing highly crystalline and scalable 2D MOFs and their alloys. Bromine intercalation merits future studies on band gap engineering in these layered materials.

An evolving understanding of elastomeric polymer nanocomposites continues to expand commercial, defense, and industrial products and applications. This work explores the thermomechanical properties of elastomeric nanocomposites prepared from bisphenol A diglycidyl ether (BADGE) and three amine-terminated poly(propylene oxides) (Jeffamines). The Jeffamines investigated include difunctional crosslinkers with molecular weights of 2,000 and 4,000 g/mol and a trifunctional crosslinker with a molecular weight of 3,000 g/mol. Additionally, carbon nanotubes (CNTs) were added, up to 1.25 wt%, to each thermoset. The findings indicate that the Tg and storage modulus of the polymer nanocomposites can be controlled independently within narrow concentration windows, and that effects observed following CNT incorporation are dependent on the crosslinker molecular weight.

Polymer matrix composites (PMCs) offer design solutions to produce smart sensing, conductive, or high performance composites for a number of critical applications. Nanoparticle additives, in particular, carbon nanotubes and metallic quantum dots, have been investigated for their ability to improve the conductivity, thermal stability, and mechanical strength of traditional composites. Herein we report the use of quantum dots (QDs) and fluorescently labeled carbon nanotubes (CNTs) to modify the thermomechanical properties of PMCs. Additionally, we find that pronounced changes in fluorescence emerge following plastic deformation, indicating that in these polymeric materials the transduction of mechanical force into the fluorescence occurs in response to mechanical activation.

Segmented ionenes are a class of thermoplastic elastomers that contain a permanent charged group within the polymer backbone and a spacer segment with a low glass transition temperature (Tg) to provide flexibility. Ionenes are of interest because of their synthetic versatility, unique morphologies, and ionic nature. Using phase changing ionene-based nanocomposites could be extended to create reversible mechanically, electrically, optically, and/or thermally responsive materials depending on constituent nanoparticles and polymers. This talk will discuss recent efforts to utilize the synthetic versatility of ionenes (e.g., spacer composition of PTMO or PEG) to prepare percolated ionic domains in microphase separated polymers that display a range of thermomechanical properties. Furthermore, by synthesizing two series of ionene copolymers with either PEG or PTMO spacers at various ratios with 1,12-dibromododecane will yield a range of ion contents (hard contents) and will impact nanoparticle dispersion.

Zwitterionic polymers, due to their supurior capability of electrostatically induced hydration, have been considered as effective functionalities to alleviate bio-fouling of reverse osmosis (RO) membranes. Bulk modification of polysulfone-based matrices to improve hydrophilicity, on the other hand, is favored due to the high membrane performance, processibility, and intrinsic chlorine resistance. Here a novel synthetic method was demonstrated to prepare zwitterionic poly(arylene ether sulfone) (PAES) copolymers, which was blended with native polysulfone (PSf) to fabricate free-standing asymmetric membranes via non-solvent induced phase separation process. Both the porosity of the support layer and surface hydrophilicity increased drastically due to the incorporation of zwitterion functionalities in the rigid polysulfone matrix. The water permeance and antifouling ability of the blend membranes were both remarkably improved to 2.5 Lm−2 h−1 bar−1 and 94% of flux recovery ratio, respectively, while salt rejection remained at a high level (98%) even under the high exposure to chlorine (8,000 ppm•h). Besides the preliminary blended membrane design, for the future membrane property enhancement, this dissertation also focused on polymer structure optimizations via elucidating the fundamentals from two perspectives: 1). Synthetic reaction kinetics and mechanisms on polycondensation of PAES. Interestingly, in combination of experiments and the computational calculations by density functional theory (DFT) methods in this work, only the aryl chlorides (ArCl) monomer follows the classical second-order reaction kinetics of aromatic nucleophilic substitution (SNAr) mechanism, while the kinetics of the aryl fluorides (ArF) reaction fit a third-order rate law. The third order reaction behavior of the ArF monomer is attributed to the activation of the carbon-fluorine bond by two potassium cations (at least one bounded to phenolate), which associate as a strong three-body complex. This complex acts as the predominant reactant during the attack by the nucleophile. 2). Optimized copolymer structures were developed for controlled high molecular weight (Mw ~ 65 kDa) and zwitterionic charge content (0~100 mol%), via off-set stoichiometry during polycondensations, following with thiol-ene click reaction and ring-opening of sultone to introduce the sulfobetaine functional groups. The structure-property-morphology relationships were elucidated for better understanding atomic-level features in the charged polymers for future high-performance desalination applications.