Browsing by Author "Wooley, Karen L."
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Item Advances of Glucose-Based Polycarbonates: From Fundamentals to Anti-Biofouling Applications(2023-01-16) Shen, Yidan; Wooley, Karen L.; Batteas, James D.; Fang, Lei; Sukhishvili, SvetlanaThe production of eco-friendly materials, in particular, sugar-based polymers, has gained extensive attention because of the great abundance of natural carbohydrates and polysaccharide resources with low cost, high degrees of structural diversity and functionality, biocompatibility and degradability. In this work, we advanced the development of naturally derived glucose-based polycarbonates through the investigation of polymerization mechanisms, determination of relationships between structures, reactivities, properties, and application toward complex surfaces capable of exerting intriguing anti-biofouling characteristics to address societal challenges. The regioselectivities of organocatalytic ring-opening polymerizations (ROPs) in a series of five-membered cyclic glucose carbonate monomers were investigated. Regioirregular poly(2,3-α-D-glucose carbonates) were afforded via the ROPs of three monomers having different cyclic acetal protecting groups through the 4- and 6- positions. A combination of 1D and 2D NMR studies of the isolated unimers and dimers revealed the backbone connectivities and ring-opening preference. Furthermore, transcarbonylation reactions in the presence of the organobase catalyst, 1,5,7-Triazabicyclo[4.4.0]dec-5-ene (TBD), were confirmed by a model reaction, which was going with the ring-opening process and scrambled the regioselectivity. Computational calculations were also performed to gain the mechanistic molecular understanding of organobase catalyzed ring-opening reactions. Further, side chain engineering is extensively used to modulate the materials with desirable behaviors and performances in practical applications. Therefore, it is essential to understand the fundamental principles of substituents in sugar-based polymers that drive the polymerization processes and material properties. Glucose carbonate monomers with variable acyclic substantial functionalities at 4- and 6- positions were designed and synthesized. The side-chain substitutions significantly affected the regioselectivities and polymerization rates during organocatalytic ROPs and the thermal properties of the derived polycarbonates. Lastly, polymer amphiphilicity is well known to affect the anti-biofouling ability in the coating systems. Herein, block PEGylated poly(4,6-α-D-glucose carbonate) with different lengths of hydrophobic segments were prepared and then fabricated into coatings on glass slides to rigorously probe their surface features through advanced characterizations and evaluate their anti-biofouling performance with various organisms. Together, understandings the physicochemical properties and surface features of PGC coatings are expected to guide toward the optimized design of materials for varying challenging conditions.Item Amphiphilic Hyperbranched Fluoropolymer Networks as Passive and Active Antibiofouling Coatings: From Fundamental Chemical Development to Performance Evaluation(2012-10-19) Imbesi, Philip; Wooley, Karen L.; Batteas, James D.; Cremer, Paul S.; Grunlan, Melissa A.The overall emphasis of this doctoral dissertation is on the design, synthesis, detailed characterization and application of amphiphilic hyperbranched fluoropolymers (HBFPs) crosslinked with poly(ethylene glycols) (PEGs) in complex polymer coatings as anti-biofouling surfaces. This dissertation bridges synthetic polymer chemistry, materials science and biology to produce functional coatings capable of fouling prevention, demonstrating thermo-controlled healing and acting as a benchmark surface to understand component:property relationships prior to increasing formulation complexities. A two-dimensional array of HBFP-PEG coatings was produced by the co-deposition of uniquely composed HBFPs with varying weight percentages of PEG. Bulk and surface properties were evaluated and assigned to formulation trends. Based on these findings, the most viable candidates were replicated and their fouling responses were assessed against three marine fouling organisms. An active mode of biofouling resistance was covalently grafted onto the surface of HBFP-PEG. The presentation of the settlement-deterrent molecule noradrenaline (NA) works in tandem with the highly-complex surface, to act as a dual-mode, anti-biofouling coating NA-HBFP-PEG. Secondary ion mass spectrometry (SIMS) was employed to quantify the extent of NA substitution. Biological assays against oyster hemocytes confirmed the activity of the grafted NA and cyprid settlement assays supported that the overall anti-biofouling ability of NA-HBFP-PEG was increased by 75%. Thermally-reversible crosslinks were installed as healable units throughout the framework of the networks, with the goal of generating coatings that could possess a greater resistance to mechanical failure. Small molecule and linear polymer models were probed by nuclear magnetic resonance (NMR) spectroscopy and gel permeation chromatography (GPC) to demonstrate the controlled reversibility of the crosslinks. Optical microscopy was employed to visualize surface scratch healing and fluorescence microscopy was used to identify the adsorption behavior of fluorescently-labeled proteins. A benchmark, anti-biofouling surface was generated through thiol-ene crosslinking of a linear fluoropolymer with pendant alkenes (LFPene) with pentaerythritol tetrakis(3-mercaptopropionate) (PETMP). Core constituents were evaluated spectroscopically and surfaces of LFPene-PETMP, along with two model surfaces that largely expressed a single component, were analyzed to understand how individual elements and blending contributed to the physical, mechanical and anti-biofouling properties to generate a performance baseline to compare against future generations.Item Aromatic and Quinoidal Conjugation of Ladder-type Macromolecules(2020-10-13) Ji, Xiaozhou; Fang, Lei; Green, Micah J.; Singleton, Daniel A.; Wooley, Karen L.Ladder-type conjugated molecules and macromolecules are attractive organic materials with optical and electronic properties suitable for various applications, as a result of their extended π-delocalization and strong intermolecular coupling facilitated by their rigid coplanar structures. This dissertation focuses on the incorporation of ladder-type constitution in aromatic and quinoidal conjugated oligomers and polymers, in order to address the fundamental challenges associated with conjugated organic materials, such as stability and limited delocalization ranges of states or quasi-particles. This dissertation begins with a brief introduction of ladder-type conjugated structures and quinoidal resonance (Chapter I). Important concepts that are involved in the following chapters are introduced and related challenges are discussed. Chapter II describes an example of conjugated ladder polymer featuring rigid coplanar backbone and self-complementary intermolecular hydrogen-bonding interactions. To address the low-solubility challenge in the field of ladder polymers, a reversible protection and cleavage strategy is employed, realizing solution-phase characterization and processing. The rigid backbone with strong intermolecular interactions leads to compact aggregation and this ladder polymer demonstrates excellent thermal and chemical stability, showing promising potential as coating materials for harsh environment applications. In Chapter III, ladder-type constitution is incorporated in a pernigraniline salt-derived system containing quinoidal building blocks. As the fully-oxidized and acid-doped derivative of polyanilines, pernigraniline salt is not well-understood due to their poor stability and configurational uncertainty. Ladder-type constitution is imparted into a series of oligomers to address these issues, demonstrating well-defined configuration and excellent chemical stability after protonation, rendering it possible to reveal the intrinsic electronic and magnetic properties of pernigraniline salt species with quinoidal moieties. A dominant Pauli paramagnetism was observed in the solid state, which indicates the delocalization nature of polarons in the ladder oligomers as a result of extended intramolecular and intermolecular interactions. Shown in Chapter IV, this design principle is expanded into a macromolecular system as ladder-type polyaniline derivatives. The chemical stability the ladder polymer ensures an unprecedented electrochemical stability of this material under highly oxidative conditions. Interconversions among different redox states have been achieved in a highly reversible and robust manner in both chemical and electrochemical processes. This material is applied in an electrochromic device, showing distinct switches between UV- and near-infrared-absorbing states with a remarkable cyclability and high tolerance to operation voltages. Overall, this dissertation is to demonstrate the strategy of incorporating ladder-type constitution in aromatic and quinoidal conjugated macromolecules to address challenges in the field of organic electronic materials in both fundamental and application research. Unprecedented properties, including enhanced stability and extended delocalization ranges of states, are investigated in ladder-type conjugated macromolecules, showing their great potential as next-generation electronic active materials.Item Assembly of Glucose-Derived Amphiphilic Polymers in Aqueous Solution: Towards Functional and Degradable Supramolecular Nanomaterials(2020-10-22) Dong, Mei; Wooley, Karen L.; Fang, Lei; Green, Micah J.; Sheldon, Matthew T.Polymer self-assembly and co-assembly have emerged as a powerful platform for the fabrication of functional nanomaterials. This dissertation research focuses on the self assembly of degradable and functional glucose-derived polymers with high structural tailorability and complexity, as well as their co-assembly with magnetic inorganic nanoparticles towards biomedical and environmental applications. Topological parameters in macromolecules, e.g., architectures, side chain and backbone lengths, and chemical constituents, have been demonstrated to be crucial in the construction of supramolecular assemblies. Therefore, a series of amphiphilic diblock copolymers were designed and synthesized with varied architectures, chemical compositions, side chain and backbone lengths. Corresponding nanostructures with different morphologies and sizes were afforded through a solvent-exchange self-assembly process. It is found that the transition in the nanoscopic features of those nanostructures, i.e. morphology and size, is mostly governed by variation in the volume fraction of amphiphilic polymers. In order to better understand the effect of fundamental molecular parameters on the supramolecular assembly of specific amphiphilic block copolymers, coil-brush block copolymer was selected as an intriguing candidate in the bottlebrush polymer family, due to its unique structure comprising of both rigid brush segments and flexible linear segments. Thus, experimental and computational self-assembly of coil-brush copolymers were studied, and found to generate two phase diagrams with a remarkable qualitative agreement, in terms of the structurally-dependent morphologies. There has been growing interest in the fabrication of functional nanomaterials by self-assembly and co-assembly of polymers. Well-defined micellar nanocomposites prepared by hybridization of glucose-derived polycarbonates and magnetic iron oxide nanoparticles have been developed to address the crude oil contamination in aquatic environment. This functional nanomaterial is designed as a recyclable nanoscopic carrier of hydrophobic pollutants, and also able to degrade into environmentally benign small molecules in the long term. Fundamental study of self-assembly and co-assembly behavior of amphiphilic polymers and their applications in functional material design have been discussed in this dissertation, suggesting a great potential in incorporation of various functions in nanomaterials by modification of polymer compositions and structures in a creative way.Item CATIONIC SHELL CROSSLINKED NANOPARTICLES AS INTRACELLULAR DELIVERY VEHICLES FOR THE DIAGNOSIS AND TREATMENT OF ACUTE LUNG INJURY(2011-08-08) Florez, Stephanie; Wooley, Karen L.; Shrestha, RituNanomedicine is a growing field of medicine that seeks to take advantage of nanoscale materials in order to address current challenges such as the ability to cross the epithelial mucus of the lungs to deliver treatment. This thesis focuses on the development of polymer nanomaterials known as shell crosslinked knedel-like (SCK) nanoparticles to serve as intracellular carriers of genetic material and specifically target injured cells in the lung for the treatment of acute lung injury (ALI). SCK nanoparticles are spherical in their morphology and their synthesis allows for them to possess tunable functionalities, size, and physical properties. The research presented in this work includes the synthesis of amphiphilic block copolymers that exhibit cationic character in their hydrophilic segment, in order to facilitate cell transfection in the body. The block copolymer poly(acrylamidoethylamine)130-block-polysterene123 (PAEA-b-PS) underwent subsequent micellization in water and crosslinking across the hydrophilic chains. The resulting SCK nanoparticles were c.a 75 nm in diameter and possessed cationic character. Herein, we report the physical and chemical characteristics of the block copolymers, micelles, and crosslinked nanoparticles. Current efforts for refining the synthetic methods in the production of SCK nanoparticles for the treatment of ALI are described.Item Conformational Control of Organic Conjugated Molecules and Macromolecules through Dynamic Noncovalent Bonds(2019-03-21) Zhu, Congzhi; Fang, Lei; Wooley, Karen L.; Gabbaï, François P.; Lutkenhaus, Jodie L.Torsional conformation of the backbone of a π‐conjugated molecule or macromolecule shapes its solubility, optical and electronic characteristics, rheological behaviors, solid‐state properties, and ultimately materials performances. This dissertation focuses on the on-demand control over the conformation of π-conjugated molecules and macromolecules using dynamic intramolecular noncovalent bonds, such as hydrogen bonds and B←N coordinate bonds. Those dynamic bonds bridged building units in a π-conjugated system so that desired conformations can be induced and then perturbed in a controlled manner. Through such an active manipulation over molecular conformation, optical band gaps, electrochemical properties, solubilities, and processabilities of organic conjugated materials can be tuned on demand. This dissertation begins with a brief introduction of the development of organic conjugated molecules and macromolecules involving a variety of bridging noncovalent bonds (Chapter I). Challenges in this specific field are identified and discussed for future breakthroughs in exploiting the promising potential of these dynamic-noncovalent‐bond‐ bridged π‐conjugated organic materials. Chapter II describes an example of conformational control in a conjugated molecule using intramolecular hydrogen bonds to achieve tailored molecular, supramolecular, and solid-state properties. The fully coplanar conformation of such molecules led to short π–π stacking distances, strong yet controllable aggregation in solution phase, and solid-state self-assembly into one-dimensional nano-/microfibers. Shown in Chapter III, this molecular design is expanded into a macromolecular π-conjugated system. A molecular engineering strategy of chemically inhibiting and regenerating intramolecular hydrogen bonds was developed to resolve the synthetic challenges and processing issues by controlling the backbone conformation. Chapter IV and V discuss the incorporation of intramolecular B←N coordinate bonds into organic conjugated molecules. In Chapter IV, it is demonstrated that the dynamic nature of such coordination allowed for active manipulation of the optical properties by using competing Lewis basic solvents. Described in Chapter V, two rigid molecular constitutions were designed to accommodate redox-active units and B←N coordination into a compact structure. These molecules demonstrated multiple electron transfer processes and multicolor electrochromism. Comprehensive experimental and computational investigations revealed the underlying mechanism of the redox processes, and the critical role of B←N coordination in rendering such redox properties. This dissertation is to understand the fundamental correlation between molecular conformation and materials properties of π-conjugated systems by employing dynamic noncovalent bonds. This dissertation discusses synthetic methodologies to incorporate dynamic noncovalent bonds into organic conjugated molecules and macromolecules. The molecular design principles and structure-property relationships between molecular conformation and materials properties were established. The active manipulation of intramolecular noncovalent bonds led to tunable molecular and supramolecular properties and enabled solution processing of rigid coplanar macromolecules.Item Constructing Degradable Polymer Materials through Chemical Transformations of Cyclic Ethers Derived From Natural Products With C1 Feedstocks(2022-12-16) Tran, David V; Wooley, Karen L.; Powers, David C.; Michaudel, Quentin; Lutkenhaus, Jodie L.This work focuses on the development of synthetic methodologies by which natural products and C1 feedstocks, such as carbon dioxide or carbonyl sulfide, can be transformed into degradable, sustainable polymer materials, thereby contributing to solutions to several current global challenges. Over the past few years, there has been a reevaluation in the methods of constructing everyday plastics which are synthesized from petroleum-based chemicals and can persist for excessively long periods of time, placing stresses on the environment. Therefore, there is a growing shift toward the use of sustainably-sourced feedstocks for the production of degradable polymers. Relevant to this aim, polymer materials constructed from carbon dioxide (CO2) and carbonyl sulfide (COS) are receiving much attention since they are ideal one-carbon (C1) building blocks for the synthesis of polycarbonates and sulfur-containing polymer, respectively, which supplements current processes to produce these degradable polymers that involve toxic reagents such as phosgene. In the following content, renewable sugar-based polymers are achieved by harnessing the chemical diversity of four-membered cyclic ethers derived from natural products to form polymeric materials imbedded with degradable linkages as alternatives to petrochemicals for commercial applications. This study has had success in utilizing naturally-derived carbohydrates to produce sustainable degradable sugar-derived polymers with the structural diversity and potential for degradability yielding promising alternatives to traditional plastics. In addition, this research investigates sustainable and green synthetic routes through utilization of captured and stored C1 feedstocks, such as CO2 and COS, as comonomers to yield high-value polymeric materials with tunable thermal and mechanical properties.Item Core-shell Inverse Amphiphilic Molecular Terpolymer Bottlebrushes Towards Lubrication and Microelectronic Applications(2022-12-13) Vazquez, Mariela; Wooley, Karen L.; Bergbreiter, David E.; Singleton, Daniel A.; Djire, AbdoulayeUnderstanding of structure-function relationships is of vital importance to produce optimum materials for progression in the microelectronics and tribological fields. This dissertation focuses on the fundamental studies to develop core-shell amphiphilic bottlebrush polymers towards their potentials as lubricant and surface neutralizing additives. Well-defined core-shell amphiphilic bottlebrush nanostructures were produced through the synthetic methodologies of controlled radical reversible addition-fragmentation chain-transfer polymerization, ring-opening metathesis polymerization, and simple and facile chemical modification. The impact of the chemical composition of the shell on the intramolecular conformations and morphologies of core-shell amphiphilic bottlebrush polymers was explored through the comparison of two bottlebrush polymers having the same hydrophilic poly(acrylic acid) core with differing shell chemistries. Poly(norbornenyl-graft-[[poly(acrylic acid)]-block-[polystyrene]]) (PNB-g-[[PAA]-b-[PS]]) and poly(norbornenyl-graft-[[poly(acrylic acid)]-block-[poly(n-hexyl acrylate)]]) (PNB-g-[[PAA]-b-[PHA]]) were synthesized. The unimolecular structures resulted in either spherical/collapsed or an extended cylindrical/worm-like morphologies visualized by atomic force microscopy (AFM) and transmission electron microscopy (TEM). Coarse-grain simulations provided further details, demonstrating qualitative agreement with the experimental data, and corroborated the bottlebrush morphological structures and conformations were dependent upon combinations of intra- and intermolecular polymer-polymer and polymer-solvent interactions. The insights to the molecular conformations and resulting elongated morphologies of the core-shell inverse amphiphilic molecular bottlebrush terpolymers were applied to investigate the macromolecules as potential lubricant additives. The lowest average in-situ coefficient of friction (COF) (0.2) and frictional force (10 mN) was achieved by the core-shell amphiphilic bottlebrush polymer additive with an alkylated-based shell at a 0.5-1.0 wt.% in dodecanes and an applied normal force of 50 mN. A 75% decrease in the in-situ COF compared to the bare substrate was observed. Overall, core-shell amphiphilic bottlebrush terpolymers outperformed their linear block copolymers counterparts as at lowering the COF. Finally, linear block copolymers with high Flory-Huggins parameter, Ⲭ, between the chemical compositions of the polymeric blocks, potential smectic physicochemical properties, or unique properties from fluorine-containing polymers were explored as materials towards lithographic molds. The difference in intermolecular and interfacial interactions provided varying domain microphase segregation and helped identify potential block copolymers as polymer matrices. Formation of lamellar domains with random orientation could benefit from core-shell bottlebrush terpolymer additives for formation of clear lamellar domains with controlled and organized anisotropic orientations for lithographic applications. This work provided vital information for the rational design of core-shell amphiphilic bottlebrush terpolymers with varying chemistries and their resulting extended or collapsed structures through the combination of experimental and computational studies and their potential as additives in the microelectronic and tribological fields.Item Covalent Layer-by-Layer Synthesis of Responsive Porous Filters(2012-07-16) Allen, Ainsley Larue; Bergbreiter, David E.; Batteas, James D.; Wooley, Karen L.; Grunlan, Melissa A.Poly(N-isopropylacrylamide) (PNIPAM), a temperature responsive polymer, undergoes a phase change at a lower critical solution temperature (LCST) in aqueous solutions. For PNIPAM this temperature is 32 °C in water. Below the LCST, the polymer is readily solvated by water. As the temperature of the solution increases, the polymer undergoes a phase transition so that above the LCST it is no longer water soluble. The LCST of PNIPAM may be changed by the addition of salt solutions from the Hofmeister series which will follow the Hofmeister effect for salting-in and salting-out the polymer. Temperature responsive polymers may be grafted to a surface in a variety of methods to create responsive thin films that exhibit a change in wettability. The surface wettability is directly related to the polymers ability to be solvated in its coil conformation. When PNIPAM is grafted to a surface, the surface becomes alternatively hydrophobic and hydrophilic in response to both temperature and the anions in the Hofmeister series which take the surface either above or below the LCST of PNIPAM. The synthesis of responsive nanocomposite grafts was successfully applied to glass slides and three-dimensional surfaces, porous glass frits which were capable of controlling the passive flow rate. The nanocomposite graft was assembled in a covalent layer-by-layer approach to create more chemically robust surfaces, and also to incorporate nanoparticles into the graft for increased surface roughness and therefore improve wettability response. Because of a much greater inherent roughness to a glass frit, characterization of the polymers and nanoparticles was performed before they were covalently bound to the surface. The final product, a functionalized frit with a PNIPAM/SiO2 nanocomposite graft, was analyzed by observing changes in the passive permeation rate of the frit between water and salt solutions. These changes in flow were indicative of the surface bound PNIPAM changing between its hydrophilic and hydrophobic conformation in response to water and concentrations of kosmotropic salts such as sodium sulfate and sodium citrate. In addition to the solute response, the frit was also determined to be responsive to temperature and concentration. Water exhibited a passive flow rate 1000 times faster than a kosmotropic salt but had a similar flow rate to that a chaotropic salt. By measuring the flow rate of 0.5 M Na2SO4 at ~7 °C in a cold room and at room temperature it was observed that sodium sulfate in the cold room passed through the frit at a rate 100 times faster than at room temperature. Because of the hysteresis of PNIPAM documented in literature, washing procedures were kept consistent between experiments to achieve more reproducible results. It was concluded that the frits were temperature responsive and had relative standard deviations below 25 percent for flow rates on a single frit. However, standard deviations of flow rates between frits were higher. This was likely due to a combination of factors, such as the frits’ pore size range of 10 μm resulting in the possibility of varied degrees of functionalization of each frit.Item Degradable polycarbonate sport fishing materials(United States. Patent and Trademark Office, 2019-06-25) Wooley, Karen L.; Felder, Sincha E.; Versaw, Brooke, A.; Jahnke, Ashlee A.; Link, Lauren A.; Wooley, Mark W.; Hinton, Charles A.; Howell, William R., Jr.; THE TEXAS A&M UNIVERSITY SYSTEMDegradable polycarbonates network based bulk materials are provided. The bulk materials of the present disclosure may be produced having a wide range of tunable mechanical, physical, and thermal properties and are hydrolytically degradable. The bulk materials of the present disclosure may be suitable for the manufacture of a variety of sport fishing equipment or other equipment for water use or that may benefit from hydrolytic degradation in the environment.Item Design and Development of Bottlebrush Polymers for Advanced Technologies(2020-07-21) Kang, Nari; Wooley, Karen L.; Elabd, Yossef A.; Fang, Lei; Lutkenhaus, Jodie L.; Sue, Hung-JueBottlebrush polymers or molecular bottlebrushs are unique polymers with a complex architecture. This cylindrical bottlebrush structure can be constructed via a “bottom-up” method through controlled radical polymerizations to synthesize macromonomers, followed by living ring-opening olefin metathesis polymerizations of macromonomer frameworks. This “bottom-up” synthetic strategy allows bottlebrush polymers to be deliberately designed to tailor their properties and their site-specific functionalization. The compositions and dimensions of bottlebrush polymers can be refined with a high degree of control over the synthetic chemistry using predetermined kinetic parameters of living free radical polymerizations throughout synthetic pathways. Additionally, the functionalities of bottlebrush polymers can be determined by a wide selection of functional monomers which can be used as building blocks for bottlebrush polymer fabrication. Employing a series of monomers with varied functionalities, from the wide range of choices, enables the realization of numerous potential applications of bottlebrush polymers. The new design, fabrication and scientific investigation of bottlebrush polymer systems for several advanced technologies will be explored and presented in this dissertation–hole transport materials for organic light-emitting diodes (Chapter II), porous membranes for gas adsorption and separation (Chapter III), and amphiphilic BBPs with high graft densities as potential templating materials for the anisotropic growth of inorganic nanoparticles (Chapter IV). Each bottlebrush macromolecule includes one or more functional moieties that assume a role to improve device performances.Item Design and Development of Intricate Nanomedical Devices through Compositional, Dimensional and Structural Control(2012-07-16) Lin, Yun; Wooley, Karen L.; Burgess, Kevin; Cremer, Paul S.; Grunlan, Melissa A.Nanomedicine, the medical application of nanotechnology, uses nanoscale objects that exist at the interface between small molecule and the macroscopic world for medical diagnosis and treatment. One of the healthcare applications of nanomedicine is drug delivery: the development of nanoscale objects to improve therapeutics' bioavailability and pharmacokinetics. Shell crosslinked knedel-like nanoparticles (SCKs), that are self assembled from amphiphilic block copolymers into polymeric micelles and then further stabilized with crosslinkers isolated throughout the peripheral shell layer, have been investigated for drug delivery applications that take advantage of their core-shell morphology and tunable surface chemistry. SCKs are attractive nanocarriers because the cores of the SCKs are used for sequestering and protecting guests. The readily adjustable shell crosslinking density allows for gating of the guest transport into and out of the core domain, while retaining the structural integrity of the SCKs. Moreover, the highly functionalizable shell surface provides opportunity for incorporation of targeting ligands for enhanced therapeutic delivery. The optimization of nanoparticle size, surface chemistry, composition, structure, and morphology has been pursued towards maximization of the SCKs' therapeutic efficacy. With distinctively different dimensions, compositions and structures of the core and shell domains of SCKs, and an ability to modify each independently, probing the effects of each is one of the major foci of this dissertation. Utilization of a living radical polymerization technique, reversible addition-fragmentation chain transfer (RAFT) polymerization, has allowed for facile manipulation of the block lengths of the polymer precursors and thus resulted in various dimensions of the nanoparticles. SCKs constructed from poly(acrylic acid)-b-polystyrene (PAA-b-PS) with various chain lengths, have been investigated on the loading and release of doxorubicin (DOX). The effect of PEGylation on paclitaxel (PTX) loaded SCKs on the cell internalization and killing was investigated. Apart from chemotherapies, the SCKs were explored as antimicrobial agents by incorporating silver species. Conjugation of the SCK surface with a protein adhesin through amidation chemistry to promote epithelial cell targeting and internalization was developed. Nanoscale assemblies with complex morphologies constructed from a linear triblock copolymer was investigated. Furthermore, a highly multifunctional nanodevice for imaging and drug delivery functionalized with a chelator for radio-labeling, polyethylene glycol (PEG) for improved biodistribution, targeting ligands, a chromophore and a therapeutic agent was evaluated in vivo as active-targeted delivery of therapeutics.Item Design and Development of Sustainable Materials with Mechanically-Interlocked Polymer Topologies to Address Environmental Challenges and Technological Limitations(2023-05-04) Pang, Ching; Wooley, Karen L.; Grunlan, Melissa A.; Michaudel, Quentin N.; Singleton, Daniel A.Slide-ring networks are complex topologies comprised of both steady covalent connections and dynamic supramolecular interactions. Due to their mechanically-interlocked polymer topology, slide-ring networks have become an emerging concept for developing materials with advanced mechanical and physical properties, including softness, elasticity, high stretchability, toughness, and high absorption capacity. This dissertation focuses on combining sustainable materials synthesized from natural feedstocks with degradable linkages and mechanically-robust polymer topology to address the significant environmental challenges and novel technological development. To address the environmental problem, a series of glucose-based degradable superabsorbent hydrogels has been designed and fabricated with the potential to tackle issues associated with sustainability, flooding, and drought, which are exacerbated by climate change. These hydrophilic networks were constructed by integrating glucose as a primary building block, both into cyclic oligomers and block polymers, which were ultimately combined into mechanically-interlocked slide-ring crosslinked materials. To improve technological limitations, thiol-ene/ -yne click chemistry was introduced into slide-ring topology for the development of versatile photoprintable materials to expand the properties of 3D printing products. These projects aim to meet needs associated with global water resource challenges and technological development while considering degradability and recyclability, through the fundamental study of structure-topology-morphology-properties of the mechanically-interlocked slide ring network.Item Development of Degradable Polymeric Nanoscopic Platforms for Imaging and Drug Delivery Applications(2018-12-05) Li, Richen; Wooley, Karen L.; Darensbourg, Marcetta Y.; Lutkenhaus, Jodie L.; Zhou, HongcaiDegradable polymers have gained increasing interest in the molecular probe and nanomedicine research, which avoid safety concerns of non-degradable materials after long-term accumulation in the human body. This dissertation focuses on the rational design and synthesis of biocompatible polymers, based on polyphosphoesters (PPEs) and poly(glucose carbonate)s (PGCs), which are capable of serving as non-immunotoxic antifouling coatings for molecular nanoprobes to accurately image tumors, or formulating well-defined functional nanocarriers for therapeutics to effectively treat osteosarcoma lung metastasis or bacterial infections. In the first study, zwitterionic PPEs (zPPEs) were developed as coating materials for gold nanoparticles (AuNPs), which showed minimal immunotoxicity and advanced antifouling property. The PPE was synthesized by a rapid organocatalyzed ring-opening polymerization (ROP), followed by post-polymerization modification via the thiol-yne click reaction to afford the zPPEs. Degradability of the zPPEs was investigated in nanopure water (pH 5-6), which proceeded to ca. 75% after 2 d, and ca. 90% by 7 d, consistent with the degradation profiles of the zPPE-coated AuNPs. Compared to their counterparts coated with poly(ethylene glycol) (PEG), the zPPE-coated AuNPs showed similar sizes and low immunotoxicity. Moreover, significantly reduced cytokine adsorption was observed for the zPPE-coated nanoparticles. The degradability, biocompatibility and advanced antifouling property demonstrate the zPPE to be a potential PEG alternative coating material for molecular nanoprobes. To circumvent potential drawbacks of our previous PPE system, namely the production of ethylene glycol and phosphoric acid upon hydrolytic degradation, sugar-derived PGC-based polymers were developed in the second study, which was utilized to formulate functional nanocarriers for anticancer drugs to treat osteosarcoma (OS) lung metastases. Two PGC-based block polymers and one dimeric paclitaxel pro-drug (diPTX) were designed to be co-assembled into nanoparticles with tunable sizes and surface charges as a redox-responsive nanomedicine. The formulation showed sustained release of the PTX free drug in the presence of glutathione, a reducing agent existing at high levels in tumor tissues, thereby resulting in significant selectivity in killing cancer cells over healthy cells. Both in vitro and in vivo anticancer studies confirmed the capability of the formulation to penetrate tumor tissues and inhibit tumor cell growth, indicating its promise for the treatment of OS lung metastases. In the third study, a novel PPE-based triblock polymer was designed and synthesized, which avoided the hydrolytic degradation product ethylene glycol, and allowed for facile construction of silver-loaded Janus nanoparticles as a potential antimicrobial. The polymer was synthesized by a one-pot sequential organocatalyzed ROP of a cyclic phosphotriester and L-lactide with PEG as the macroinitiator, followed by post-polymerization modification via the thiol-ene click reaction. Biocompatibility of the polymer was confirmed by cytotoxicity assays. The well-defined silver-loaded Janus nanoparticles were then prepared by simply irradiating the mixture of the PPE-based polymer and silver acetate solutions under UV for a few minutes. Within 2 h dialysis against nanopure water, ca. 50% of silver was released from the Janus nanoparticles, with the remaining silver released in a much slower manner over 40 h, which could be beneficial in treatment of bacterial infections.Item Development of Stimuli-responsive Polypeptide-based Gelators for Bioapplications and Photo-patterning Technologies(2017-04-13) He, Xun; Wooley, Karen L.; Burgess, Kevin; Fang, Lei; Grunlan, Melissa A.The past decade has witnessed significantly increased interest in the development of smart polypeptide based organo- and hydrogel systems with stimuli responsiveness, especially those that exhibit sol–gel phase-transition properties, with an anticipation of their utility in the construction of adaptive materials, sensor designs, and controlled release systems, among other applications. This dissertation highlights the rational design and development of polypeptide-based gelators for simple and easily-controlled preparations toward bioapplications and photo-patterning technologies, including full characterization studies of the compositions, structures and properties. The continuous N2 flow technology for controlled ring-opening polymerization of N-carboxyanhydride (NCA) was recently developed in our lab for construction of well-defined polypeptides, facilitating the investigations of structure-property relationships within polypeptide materials. Based upon this technology, a multi-responsive triblock hydrogelator was synthesized, which exhibited heat-induced sol-to-gel transitions and either sonication- or enzyme-induced gel-to-sol transitions. The formation of β sheets further displayed tertiary ordering into fibrillar structures that, in turn generated a porous and interconnected hydrogel matrix. The reversible macroscopic sol-to-gel transitions triggered by heat and gel-to-sol transitions triggered by sonication were correlated with the transformation of nanostructural morphologies, with fibrillar structures observed in gel and spherical aggregates in sol, respectively. The enzymatic breakdown of the hydrogels was also investigated. This allyl-functionalized hydrogelator can serve as a platform for the design of smart hydrogels, appropriate for expansion into biological systems as bio-functional and bio-responsive materials. This hydrogelator also displayed capability to dispersing and gelating single-walled carbon nanotubes (SWCNTs) noncovalently in organic solvents, resulting in significant enhancement of the mechanical properties of polypeptide based organogels and unique supramolecular structures, with results presenting in the second study. Based on the above two studies, a strategy for reversible patterning of soft conductive materials is developed. This strategy was enabled by a responsive composite that comprises peptide-based block copolymer hydrogelators and photo-thermally-active carbon nanotubes. This composite photo-responsive gelation at application relevant timescales (< 10 s), allowing for rapid and spatially-defined construction of conductive patterns (> 100 S m-1), which, additionally, hold the capability to revert to sol upon sonication for reprocessing.Item Disk-cylinder and disk-sphere nanoparticles via a block copolymer blend solution construction(Nature Communications, 2013) Zhu, Jiahua; Zhang, Shiyi; Zhang, Ke; Wang, Xiaojun; Mays, Jimmy W.; Wooley, Karen L.; Pochan, Darrin J.Item Evolution of Molybdenum Disulfide on Metal Surfaces(2021-02-24) Wu, Fanglue; Batteas, James D.; Qian, Xiaofeng; Banerjee, Sarbajit; Wooley, Karen L.Molybdenum disulfide (MoS2) has attracted tremendous attention over the past decade due to their exciting mechanical, electronic and frictional properties. Heterostructures of semiconductors and metals are the fundamental components of modern electronics. The atomically thin MoS2 sheets, offer unique opportunities for heterostructure devices since they are chemically homogenous, but illustrate electronically distinct semiconducting (1H phase) and metallic (1T phase) characteristics with matched lattices. Here, Au substrates were used to introduce phase transition inside single layer MoS2. The formation of 1T-MoS2 phase could be initiated by the charge transfer and the built-in strain from Au substrates. Because the unavoidable aging and degradation of MoS2, significantly affected the desired performance in semiconductors, catalysts and tribological applications, the structural and chemical evolution of MoS2 under accelerated aging conditions was investigated under UV-ozone condition. We found that, the aging varied strongly with the layer thickness of MoS2 sample. To systematically tune the electronic properties of MoS2, diacetylenethiolate-based molecules could be implemented to dope MoS2 via defect engineering since the thiol groups could bond to sulfur vacancies and the diacetylene thiols could form relatively stable polymers on MoS2 surfaces through UV-induced crosslinking. The mechanical and electronic properties of diacetylene and poly-diacetylene monolayers on Au(111) were fully investigated. The monolayers were found to exhibit higher friction following polymerization due to structural changes in the films. Electronically, size-dependent differences in the electronic properties were found to arise for polydiacetylene islands of around 10 nm when embedded into a dodecanethiolate matrix, which could be attributed to the Coulomb blockade. The knowledge revealed here will guide future designs and applications of MoS2-based electronic devices and tribological systems.Item Flame Retardant/Thermal Protection Nanocoatings: Meeting Industrial Challenges of Layer-by-Layer Assembly(2020-03-04) Lazar, Simone T.; Grunlan, Jaime C.; Bergbreiter, David E.; Green, Micah J.; Wooley, Karen L.Polymeric materials are widely used in every day applications, despite being highly flammable. In an effort to decrease the flammability of these materials, environmentally-benign nanocoatings have been deposited on common polymeric substrates via layer-by-layer assembly. This technique has recently gained immense interest, as it allows for nanoscale control of thickness and composition, ambient processing, and enables the incorporation of different components necessary for flame suppression. Despite the versatility and ease of layer-by-layer assembly, there are still a few drawbacks associated with this technique that make it challenging to commercialize. This dissertation describes work done to develop sustainable, flame retardant nanocoatings for commodity polymers, with each study having a specific aim of overcoming industrial challenges of layer-by-layer assembly, including practicality, preservability, and processability.Item Functional, cross-linked nanostructures for tandem optical imaging and therapy(United States. Patent and Trademark Office, 2017-05-30T00:00:00Z) Neumann, William L.; Dorshow, Richard B.; Freskos, John N.; Wooley, Karen L.; Lee, Nam S.; Lin, Yun; Sun, Guorong; Mallinckrodt LLC; Washington University; The Texas A&M University SystemThe present invention provides optical agents comprising optically functional cross linked supramolecular structures and assemblies useful for tandem optical imaging and therapy. Supramolecular structures and assemblies of the present invention include optically functional shell-cross linked micelles wherein optical functionality is achieved via incorporation of one or more linking groups that include one or more photoactive moieties. The present invention further includes imaging and therapeutic methods using one or more optical agents of the present invention including optically functional shell cross-linked micelles having an associated therapeutic agent.Item Functional, cross-linked nanostructures for tandem optical imaging and therapy(United States. Patent and Trademark Office, 2016-03-29) Neumann, William L.; Dorshow, Richard B.; Freskos, John N.; Wooley, Karen L.; Lee, Nam S.; Lin, Yun; Sun, Guorong; Mallinckrodt LLC; The Texas A&M University System; Washington UniversityThe present invention provides optical agents comprising optically functional cross linked supramolecular structures and assemblies useful for tandem optical imaging and therapy. Supramolecular structures and assemblies of the present invention include optically functional shell-cross linked micelles wherein optical functionality is achieved via incorporation of one or more linking groups that include one or more photoactive moieties. The present invention further includes imaging and therapeutic methods using one or more optical agents of the present invention including optically functional shell cross-linked micelles having an associated therapeutic agent.