Good processability is often required for applications of conducting materials like polyaniline (PANI), carbon nanotubes (CNTs) and graphene. This can be achieved by either physical stabilization or chemical functionalization. Functionalization usually expands the possible applications for the conducting materials depending on the properties of the functional groups. Processable conducting materials can also be combined with other co-dissolving materials to prepare composites with desired chemical and physical properties.

Polyanilines (PANI) doped with dodecylbenzenesulfonic acid (DBSA) are soluble in many organic solvents such as chloroform and toluene. Single wall carbon nanotubes (SWCNTs) can be dispersed into PANI/DBSA to form homogeneous solutions. PANI/DBSA functions as a conducting surfactant for SWCNTs. The mixture can be

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combined with two-parts polyurethanes that co-dissolve in the organic solvent to produce conducting polymer composites. The composite mixtures can be applied onto various substrates by simple spray-on methods to obtain transparent and conducting coatings.

Graphene, a single layer of graphite, has drawn intense interest for its unique properties. Processable graphene has been produced in N-methyl-2-pyrrolidone (NMP) by a one-step solvothermal reduction of graphite oxide without the aid of any reducing reagent and/or surfactant. The as-synthesized graphene disperses well in a variety of organic solvents such as dimethylsulfoxide (DMSO), ethanol and tetrahydrogenfuran (THF). The conductivity of solvothermal reduced graphite oxide is comparable to hydrazine reduced graphite oxide.

Attempts were made to create intrinsically conducting glue comparable to mussel adhesive protiens using polyaniline and graphene. Mussels can attach to a variety of substrates under water. Catechol residue in 3,4-dihydroxyphenylalanine (L-DOPA) is the key to the wet adhesion. Tyrosine and phosphoserine with primary alkyl amine groups also participate in adhesion. A novel water soluble synthetic mussel adhesive containing both catechol and amine groups are synthesized in a simple approach. A polyallylamine backbone is used to take the place of the polyamide chain. Catechol is appended to the backbone as the key cross-linking group. Compared to polyallyamine, poly[N-(3,4- dihydroxybenzylidene)allylamine] exhibits good adhesion under alkaline water due to moderate cross-linking. When exposed to cross-linkers, this synthetic mussel adhesive can form a hydrogel at a very low concentration.

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Various methods were tried to attach catechol group onto polyaniline and graphene to make synthetic conductive mussel adhesive. Although the chemistry proved to be successful, the material doesn't show great adhesion to selected substrates probably due the nature of the backbone and difficulties associated with its processability.

Long cycle life and high energy/power density are imperative to electrochemical energy storage systems. Conducting polymers like polyaniline have shown great potential as electroactive electrode materials but are limited by poor cycling and rate performance. To address these challenges, we have developed molecular engineering approaches to construct advanced conducting polymer hybrid materials for high-performance supercapacitors. One approach is enabled by the formation of covalent linkages between a 3D graphene network and short-chain conducting polymers built through azide click chemistry. An ultralong cycle life can be achieved by the designed electrode material while the capacitance can be further boosted using a redox-active electrolyte. We further seek to develop a scalable, effortless, and cost-efficient approach toward the fabrication of conducting polymer-based electrodes to reduce the time/energy consumption associated with conventional high-temperature synthetic methods. A simple one-step laser-induced stabilization of aniline oligomers on carbon nanotubes is established through amide covalent coupling. By taking advantage of the short-chain conducting polymers and the covalent connections, the designed electrode exhibits remarkable cycling stability and good rate capability. To further understand the capacitance degradation mechanisms of aniline oligomer-based materials during long-term cycling, two composite electrodes based on aniline trimers and carbon nanotubes are studied as model systems and are systematically investigated at both pre-cycling and post-cycling states through physicochemical and electrochemical characterizations. Furthermore, a promising nanocomposite based on an interpenetrating network of polyaniline and lignosulfonate has been designed as a waste-to-wealth approach to improve the supercapacitive performance of polyaniline. Additionally, a facile and green electrosynthesis approach is presented to fabricate a polydopamine nanofilm supported on oxygen-functionalized carbon cloth, which delivers high energy density and outstanding cycling stability. These studies present effective molecular design and facile fabrication approaches toward next-generation flexible, robust, and sustainable energy storage devices.

The rapid development of synthetic conjugated materials has enabled organic electronic devices such as solar cells, field-effect transistors and sensors to rival their inorganic counterparts in performance at significantly lower cost. Conducting polymers such as polyaniline constitute an important class of such materials, but their properties are difficult to study due to polydispersity, complex chain conformations and lack of solubility. In particular, assembling conducting polymers into highly crystalline domains similar to that of small molecule (semi)conductors has proven to be challenging, which has limited their integration into electronic devices that require high carrier mobility and stability such as organic field-effect transistors and solar cells. On the other hand, oligomers represent a unique middle ground between conducting polymers and molecular (semi)conductors because oligomers (e.g. oligoanilines) retain the chemical properties of the parent polymer, while also possessing properties typically associated with molecular (semi)conductors especially in regard to monodispersity and self-assembly. In this thesis, an oligomer approach for advancing the field of conducting polymers is presented. A myriad of conjugated oligomers are examined as the more structurally rigid, pure, and soluble model systems to tackle important challenges in this field. This approach has opened new opportunities for (1) understanding the fundamental packing, transport, and self-assembly properties for polymers; (2) the rational design of high performance conducting polymers by analyzing the oligomer building blocks; (3) realizing the long-sought solution-based bottom-up growth for vertically oriented arrays of organic single crystals; and (4) deciphering the role of oligomers in improving the crystallinity of the parent polymers. The advancement of knowledge in these fields has also allowed us to create high performance hybrid solar cells, complex core/shell nanostructures, and microcontact printing methods with nanoscale resolution.

Energy storage devices, especially batteries, are indispensable in modern society, providing power for electronic devices including smartphones and electric vehicles (EVs), and storing renewable energy for the electric grid. However, batteries still have a lot of problems, such as their limited energy density, slow charging speed, high cost, short cycle life, etc. To tackle these challenges, the development of new battery materials using earth-abundant inexpensive elements prepared through facile and scalable methods is discussed in this dissertation. First, croconic acid is proposed as a new-class of high-voltage, high-capacity organic cathode materials for lithium-ion batteries (LIBs). The theoretical redox potentials are obtained through DFT calculations and the redox reaction mechanisms are investigated by CV tests limiting the potential ranges. The high-voltage redox activity (~4 V) was confirmed by assembling two-chamber cells. In chapters 3 to 5, the effect of 3D micro- and macro-structures for battery electrodes on the battery performance is discussed. The structures are mainly engineered using a 3D printer, and the 3D electrodes are applied to sodium-ion battery anodes, supercapacitors, and lithium-metal anodes for structural lithium-ion batteries (LIBs). The 3D channels were designed to allow fast ion transport through the electrodes, which enables high mass loadings up to 100 mg cm-2 without sacrificing the intrinsic battery performance. The sodium-ion storage mechanisms in carbon materials were also elucidated through ex situ XRD analysis. In chapters 6 and 7, two scalable and inexpensive synthesis methods for silicon/carbon composites, namely, laser synthesis and re-precipitation synthesis, are proposed for low-cost, high-performance LIBs. The composites prepared through these methods possess longer cycle lives compared to conventional processes. In chapter 8, zinc-ion batteries (ZIBs) are discussed as an alternative to LIBs for grid energy storage. A new synthesis method for Zn-Mn spinel nanoparticles (~5 nm in size) is proposed as an inexpensive and high-performing cathode material; this achieved one of the highest energy densities for ZIBs. The zinc-ion storage mechanisms in Zn-Mn spinel are also elucidated through materials characterizations using ex situ X-ray diffraction and operando cell pressure measurements.

To date, there has been no comprehensive attempt to perform and/or describe catalytic reactions in the gas phase that utilize metal-organic frameworks (MOFs) as catalysts. In addition, there has been no attempt to reaction engineer these MOF catalysts in order to determine their regimes of optimal catalytic activity and possible limitations to their use. A zinc-based MOF that has been post-synthetically modified with a homogeneous palladium catalyst, Pd(CH₃CN)₂Cl₂, is used to catalyze the hydrogenation of propylene. The catalyst is assembled in a packed-bed reactor under a continuous flow of reactants. The reaction is optimized with respect to isoreticular metalation, reactant flow rate, and reactor temperature. Maximum catalytic conversion is found at intermediate metalations of 40% and 60%, high hydrogen flow of 50 ccm, and intermediate reactor temperatures of 100 °C and 150 °C.

The MOF-60 catalyst is exposed to a traditional catalyst poison, carbon monoxide (CO). It is found that the MOF is reversibly poisoned upon introduction of CO. Upon poisoning, catalytic conversions rates of 90%-100% are dramatically reduced to less than 10%-30%, depending on the CO flow rate and the reactor temperature. The CO poisoning is shown to be reversible, a similar effect as found with palladium on carbon (Pd/C). The time scale of poisoning and recovery is very fast for both the MOF catalyst and Pd/C (approximately 10-30 seconds).

Other effects of temperature on the MOF-40 are also investigated. At fixed reactant flow, the temperature grid is partitioned into finer steps of 10 °C to determine the temperature that yields the highest catalytic conversion. It is found that conversion is nearly uniform in the range between the highest conversions, i.e., conversion plateaus between the optimum temperatures. The catalyst also exhibits a weak thermal hysteresis. There is no significant improvement in conversion with thermal cycling after alternating the reactor temperature between 100 °C and 200 °C for 8 hours.

Energy storage devices allow us to charge portable electronics and use them when a wired energy source, such as a power outlet, is not available. One type of energy storage device is a supercapacitor. Supercapacitors store electrical energy through electric double layers and are based on positive and negative ions interacting with the surface of an active material. The active material is very important in determining the supercapacitor's ability to store charge, the time it takes to store charge, and the number of times the supercapacitor can be charged and discharged. The ideal active material has a large accessible surface area and high electrical conductivity. The use of flash converted graphene as an active material in supercapacitors is investigated. These supercapacitors are shown to have capacitive behavior that surpasses that of current commercial supercapacitors. Flash converted graphene is a graphene material prepared by using a flash lamp to photothermally deoxygenate graphene oxide, an oxidized form of graphite. The flashing process creates a graphene material that has an advantageous 3D corrugated morphology relative to other types of graphene materials.

Energy storage technologies have emerged as a critical component in the sustainable development of the global energy landscape. Aqueous energy storage systems are considered to be a promising solution to reliably store the energy generated from renewable sources and deliver electricity to the grid on demand. From bulk storage to uninterrupted power supply, large-scale energy storage systems of various power capacity and discharge frequency are needed, requiring rational designs of different electrochemical systems. In this work, unconventional high-energy-density supercapacitors and innovative fast-charging batteries are explored. Utilizing a facile laser scribing fabrication approach, earth-abundant, low-cost, electrochemically active vanadium oxides are incorporated onto highly conductive graphene scaffold. Symmetric supercapacitors based on this composite electrode exhibit high energy densities that are close to conventional batteries. Furthermore, with synthetic modifications, the vanadium oxides/graphene composite is applied as the cathode material in a zinc-ion battery, leading to state-of-the-art rate capability and high-rate cycling stability. Moreover, the synthesis and charge storage mechanism of the pseudocapacitive electrode are further investigated in an aqueous hybrid Li-ion battery.

Compared to rechargeable batteries, supercapacitors, also known as ultracapacitors or electrochemical capacitors demonstrate higher power and much greater cycle life. As the demand increases for energy storage devices with safe operations, high power ratings and long cycle life, supercapacitors have attracted much attention from both industry and academia. However, most commercial supercapacitors are carbon based, capable of storing only a fraction of the amount of charge that batteries do, limiting their applications to those that need short power bursts, but lower capacities. To enhance the energy density of supercapacitors, pseudocapacitance materials, such as transition metal oxides/hydroxides and conducting polymers, are introduced.

Polyaniline is a promising pseudocapacitance material with high conductivity, tunable morphology and high theoretical specific capacitance. Tetra-aniline (TANI) is the shortest oligomer of PANI that demonstrates high conductivity and redox activities. Furthermore, the short chain length of TANI is believed to improve its resistance to chain breaking during cycling that undermines PANI’s cycle stability. However, compared to PANI, research on the synthesis and supercapacitor applications of nanostructured TANI is relatively scarce. Therefore, the goal of this thesis is to develop methods to prepare TANI with various nanostructures and study the supercapacitor applications of TANI-based supercapacitors.

Chapter 2 presents a facile interfacial chemical synthesis to produce high purity TANI nanowires, while Chapter 3 is a study on the electrochemical deposition of TANI on different substrates using aniline dimer in organic-aqueous electrolyte solutions. Both methods are able to trigger nanostructure formation within TANI, and improve upon the pseudocapacitor performances of the TANI-based electrodes. Chapter 4 reports an original one-pot-one-step hydrothermal synthesis of reduced graphene oxide (rGO) - oligoaniline (OANI) nanocomposites. This process simultaneously reduces graphene oxide and deposits oligoaniline onto the rGO surfaces, inducing synergetic effects between the conducting oligomer and the carbon substrates. Chapter 5 presents an in-depth evaluation on the supercapacitor performances of TANI and its carbon nanocomposites. We composited TANI with 1D (carbon nanotubes), 2D (GO and rGO) and 3D (activated carbon) carbon materials to investigate how morphology and surface functional groups affect the supercapacitor performances of TANI-based electrodes.

Polymeric materials are proposed for applications in a variety of fields including and not limited to: biomedical applications, electronics, biosensor devices and water treatment. Covalent functionalization of these materials provides an effective means to adjust surface properties. These covalent approaches benefit more than noncovalent alternatives because they are more robust, creating stable attachment of groups with specific functional properties. Specifically, photoinitiated grafting can be performed under mild reaction conditions and low temperatures with high selectivity compared to other grafting techniques. Perfluorophenylazide (PFPA) chemistry has been used as a coupling agent for fluorinated phenylazide, which are capable of forming stable covalent bonds to sp2 or sp3 hybridized carbons or nitrogens. Phenylazides are popular because they are relatively simple to prepare, have fast kinetics, possess high reaction efficiencies, are easy to store and can covalently link organic or inorganic materials. We propose to synthesize PFPA polymers and small molecules to graft a variety of materials to enhance the materials surface properties. These materials include polymers, semiconductor surfaces, metals, carbons and metal oxide surfaces. The surface properties altered include increased hydrophilicity and conductivity, lowered surface roughness, and reactivity of the surface. We have successfully modified a variety of surfaces and enhanced specifically the rejection and fouling capability of water purification membranes and a variety of other materials. In conclusion, we were able to successfully synthesize a variety of polymers and small molecules for modification of water purification membranes.

The goals of this dissertation are to investigate perfluorophenylazide chemistry and its use in a variety of materials to create covalently bonded coatings to enhance materials properties. Chapter 1 provides an introduction, while Chapter 2 compiles detailed performance of a tetraaniline coating on ultrafiltration membranes with respect to anti-fouling properties. Chapter 3 briefly describes a project investigating the synthesis and properties of the octamer of aniline. Chapter 4 discusses a collaborative project in creating polymer coatings on nanofiltration membranes to enhance divalent ion rejection. In Chapter 5, ethyleneimine and sulfonates are coated onto polypropylene separators used in lithium-sulfur batteries to enhance the capacity of the batteries by preventing polysulfide migration. In Chapter 6, zwitterions are coated onto polydimethylsiloxane to prevent biofouling in biomedical devices.

Water scarcity is one of the most critical challenges faced by mankind and it is only getting worse due to source pollution and rising population. There is critical need for the development of water filtration membranes in order to treat polluted water and turn water from non-potable sources such as waste waster and ocean water into freshwater for human consumption and agricultural irrigation. Filtration Membranes are generally classified into four categories: microfiltration (MF), ultrafiltration (UF), nanofiltration (NF) and reverse osmosis (RO), with decreasing pore size for rejecting different sized substances. Commercial filtration membranes are able to provide decent flux and rejection for their targeted applications. However, most of them suffer from fouling issues when the microorganisms and organic matter such as proteins and polysaccharides in the water source deposit onto the membrane surface, impeding the permeation of water and lowering the flux. Therefore, it is of high demand to develop membranes that are anti-fouling. Foulants such as protein particles adhere to the membrane surface via hydrophobic interactions. In order to minimize such effects, a typical way is to increase the hydrophilicity of the membrane by surface modification or by utilizing hydrophilic membrane materials. Foulants also tend to get trapped in the open “pores” on a rough membrane surface with ridges and valleys. It is then expected that a smoother membrane surface tend to lessen such effects. Incorporating antimicrobial properties into the membrane is also an effective way to reduce fouling as this inhibits the growth of microorganisms on the membrane surfaces. New materials are also used to fabricate membranes with improved performance. Conducting polymers have recently been discovered as a new category of membrane-making materials that are hydrophilic and low-fouling. A new type of polyaniline derivative has been used to fabricate UF membranes that demonstrate chlorine resistance and anti-fouling properties. Nanostructured polyanilines are highly processable and possess unique properties that can be used in the membrane field as well as many other applications such as sensors, electrochromic devices, supercapacitors and antistatic coatings with enhanced performance, as described in a review section at the end of this thesis.