The re-emergence of interest in organic semiconducting small molecules and polymers during past several decades can be attributed to their advantage of utility, flexibility, ease of access, and turnability over silicon based inorganic semiconductors. The library of organic semiconductors containing p-type (hole conducting) and n-type (electron conducting) materials have grown in numbers and efficiency. The p-type semiconducting materials hold an advantage over n-type materials owing to their stability and ease of synthesis. The widespread use of fullerenes (C60 and C70) as n-type materials in organic photovoltaics OPVs and their known downsides of poor absorption in visible and NIR region and limited charge carrier transport have triggered the development of non-fullerene based electron accepting (NFEA) materials . By taking advantage of the electron accepting behavior of cyclopenta[hi]aceanthrylene fragment of C70, we have synthesized a new class of cyclopentafused polyaromatic hydrocarbons (CP-PAHs). These new contorted CP-PAHs have been prepared utilizing the modified version of our previously developed palladium catalyzed cyclopentannulation strategy. The target molecules broaden the scope of annulation chemistry to 1,2-bis(5-hexylthiophen-3-yl)ethyne with aryl dibromo derivatives of anthracene, pyrene and perylene to yield 4,4',4'',4'''-(cyclopenta[hi]aceanthrylene-1,2,6,7-tetrayl)tetrakis(2-hexylthiophene), 4,4',4'',4'''-(dicyclopenta[cd,jk]pyrene-1,2,6,7-tetrayl)tetrakis(2-hexylthiophene) and 1,2,7,8-tetrakis(5-hexylthiophen-3-yl)-1,2,7,8-tetrahydrodicyclopenta[cd,lm]perylene. Scholl cyclodehydrogenation of the cyclopentafused thiophene units with suitably substituted hydrocarbons chains provided access to p-extended polyaromatic systems including 2,5,11,14-tetrahexylrubiceno[5,4-b:6,7-b':12,11-b'':13,14-b''']tetrathiophene, 2,5,11,14-tetrahexyldithieno-[4,5:6,7]indeno[1,2,3-cd]dithieno[4,5:6,7]indeno-[1,2,3-jk]pyrene, and 2,9,12,19-tetrahexyldithieno[4,5:6,7]indaceno[1,2,3-cd]dithieno[4,5:6,7]indaceno[1,2,3-lm]perylene. The fully conjugated p-electronic core of these small molecules provide low optical band gaps, decent mobilities and broad absorption. The HOMO and LUMO energies of these CP-PAHs were found to be in the range of -5.48 to -5.05 eV and -3.48 to -3.14 eV, respectively. Besides showing broad band absorption features, some derivative were found to operate as a p-type semiconductor when tested in organic field effect transistors. Anthradithiophene (ADT) is an isoelectronic analogue of pentacene and became a point of interest. A soluble, and functionalizable ADT derivative, 5,11-dibromoanthradithiophene was prepared and then polymerized utilizing Stille, Sonogashira and Yamamoto cross coupling strategies. The newly developed ADT polymers were found to operate in p-type regime when tested in organic field effect transistors. To explore the effects of solvent on growing polymer chains in step-growth polymerizations, we developed a library of Yamamoto and Glaser polymers. The hypothesis tested was that growing polymer chains can recruit further monomer units to create block character in the growing polymer chains. Our investigations reveals that the solvent conditions altering the polarity of the reaction mixture can cause up to 40% preference of blockiness in the growing polymer chains.

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第19736号 / 工博第4191号 / 新制||工||1646(附属図書館) / 32772 / 京都大学大学院工学研究科物質エネルギー化学専攻 / (主査)教授 村田 靖次郎, 教授 大江 浩一, 教授 小澤 文幸 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

This thesis focuses on the electrical output of polyaniline films subjected to uniaxial strain in hydrochloric acid solutions. Polyaniline belongs to novel class of materials known as conducting polymers. Alternating single and double bonds in the backbone of conducting polymers allow them to transmit electric charge when they are doped with negatively charged ions. Modifying the degree of doping and other electrical/chemical treatments allow conducting polymers to exhibit conducting, semi-conducting, or insulating electrical properties. Resilient mechanical properties, good processability, and low cost make conducting polymers good candidates for applications traditionally held by metals and semi-conductors. When tensile strain is applied to polyaniline in an electrolyte solution, the material selectively absorbs negatively charged ions. This charge imbalance produces a measurable electrical output. Theoretical models based on Fick’s second law of diffusion were compared against experimental results to determine fundamental material properties such as diffusivity and ion solubility in polyaniline. These properties were used to quantify polyaniline as a sensor material based on characteristics including sensitivity, accuracy, precision, range, linearity, and error. Films were cast from solutions of polyaniline powder (Mn = 65,000) in N-methyl-2-pyrrolidinone solvent, with thicknesses ranging from 2.72 to 158 µm.

Conjugated polymers are semiconducting materials that are currently being researched for numerous applications from chemical and biological sensors to electronic devices, including photovoltaics and transistors. Much of the novel research on conjugated polymers is performed in academic settings, where scientists are working to prepare conjugated polymers for commercially viable applications. By offering numerous advantages, inherent in macromolecular materials, conjugated polymers may hold the key to cheap and environmentally friendly manufacturing of future electronic devices. Mechanical flexibility, and solvent-based coating processes are two commonly cited advantages. Transitions in the backbone conformation of polythiophenes (PT) in organic solvents have been widely observed to influence thin-film morphology. However, conformational transitions of water-soluble PT derivatives, with respect to their intramolecular versus intermolecular origin, remain largely obscure. Here, conformational transitions of a water- soluble polythiophene in aqueous ionic surfactants are investigated by means of Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), polarizing optical microscopy (POM), ultraviolet-visible (UV-Vis) absorption and fluorescence spectroscopy, and various X-ray scattering techniques. As-prepared complexes exist as stable hydrogels. Upon dilution, a significant time-dependent chromism occurs spontaneously. A coil-to-rod conformational transition is identified in this mechanism and verified using small-angle x-ray scattering (SAXS). Study into the corresponding kinetics demonstrates an inverse first-order rate law. It is found that the conformational transition is thermally reversible and concentration-independent. The critical transition temperature is largely dependent on the surfactant formulation. A theoretical model is presented to explain this new phenomenon and the mechanisms behind its influence on the optoelectronic and solid-state morphological properties. A relationship between the dilute-solution processing with surfactants and the final properties of the system is substantiated.

There is a need for a minimally invasive delivery method to enable cell therapies to combat peripheral artery occlusive disease (PAOD) in end stage patients. Myoblasts show promise as a cell mediated therapy but warrant an improved delivery method to increase cell retention in the region of interest because of their adherent nature, relative to previously used BM-MNC’s that are non-adherent. Contemporary issues with achieving successful cell therapies of vasculature can be mainly characterized by the lack of clinical translation from promising animal studies and absence of cell delivery scaffolding. Naturally, polymers have been widely experimented with as grafts to both culture and implant cells into tissue with recognizable success due to their analogous physical properties, such as stiffness, hydrophilicity, & surface energy, that mimic tissue conditions. Polymers having similar mechanical properties to anatomical structures are conducive to cell integration & retention, making polymers an effective biomaterial choice as a cell delivery vehicle. This thesis will evaluate the application of N-isopropylacrylamide (NIPAM) based copolymers as a biomaterial scaffold for myoblast delivery, as it is one of the most widely used biocompatible polymers with thermoreversible properties that is non-toxic and has manipulatable mechanical properties. We hypothesized that fluctuations in polymer construct stiffness, surface energy, and water retention affect myoblast proliferation & viability within the cell delivery vehicle. After measuring the physical properties and cellular proliferation in for each polymer composition, the goal of this thesis was to establish a statistical model to characterize the effect of polymer material properties on myoblast behavior and create a predictive model to optimize further iterations of NIPAM-based copolymers for cell delivery.

Intravascular devices, such as stents, must be rigorously tested before they can be approved by the FDA. This includes bench top in vitro testing to determine biocompatibility, and animal model testing to ensure safety and efficacy. As an intermediate step, a blood vessel mimic (BVM) testing method has been developed that mimics the three dimensional structure of blood vessels using a perfusion bioreactor system, human derived endothelial cells, and a biocompatible polymer scaffold used to support growth of the blood vessel cells. The focus of this thesis was to find an in-house fabrication method capable of making cellular scaffolding for use in the BVM. Research was conducted based on three aims. The first aim was to survey possible fabrication methods to choose a technique most appropriate for producing BVM scaffolding. The second aim was to set up the selected fabrication method (electrospinning) in-house at Cal Poly and gain understanding of the process. The third aim was to evaluate consistency of the technique. The work described in this thesis determined that electrospinning is a viable fabrication technique for producing scaffolding for BVM use. Electrospun scaffolding is highly tailorable, and a structure that mimics the natural organization of nano sized collagen fibers is especially desirable when culturing endothelial cells. An electrospinning apparatus was constructed in house and a series of trial experiments was conducted to better understand the electrospinning process. A consistency study evaluated scaffold reproducibility between different spins and within individual spins while setting a baseline that can be used for comparison in future work aimed at electrospinning.

Abstract: Under normal sealing and storage conditions, Nylon-6, poly-caprolactam-based plastic laminates may release impurities to packaged foods and liquids and the application of heat for cooking often increases the rate of migration. Epsilon-caprolactam is one of the main contaminates found to migrate from a Nylon-6 poly-caprolactam plastic film. The objectives of this study were to determine the effects of solvent, transportation and storage time on the migration of ε-caprolactam from a Nylon-6-based lidding material into water or a white wine substitute (12% ethanol). Polypropylene plastic cups were filled, sealed, packaged, stacked and exposed to a simulated 3-day cross-country shipment. Cups were sampled with or without simulated shipment after 0, 7, 14 and 28 days at 20.6°C. Epsilon-caprolactam was determined using a GC equipped with FID and a Restek Rtx 1301 megabore column. Results of the study indicated migration of ε-caprolactam into containers at the time of sealing with significantly higher levels (4.42 ppm average) occurring in cups containing 12% ethanol vs. water (0.01 ppm average). After the cups were sealed, neither simulated cross-country shipment nor storage increased levels of ε-caprolactam in either solvent. The results indicate that wine sealed in packages lined with Nylon-6-based plastic could contain significant amounts of ε-caprolactam. However, it is not understood how the alcohol, whether as liquid or vapor, interacted with the lidding material to increase migration at the time of sealing. No delamination of the polypropylene layer in the lidding material was observed after sealing. Future research needs to be conducted to study the effects of alcohol, alcohol vapor, sealing time and temperature on ε-caprolactam migration.

Increasing water reuse opportunities for communities has become increasingly important as access to clean water is becoming more scarce. Reverse Osmosis (RO) is an advanced treatment technology used in water recycling wastewater for potable reuse applications. RO is a promising technology; however, the membranes have limitations including their high energy demand and their susceptibility to membrane fouling. The main objective of this study was to develop a reproducible method for the fabrication of RO membranes with enhanced flux and reduced susceptibility to fouling. Literature contains numerous publications on fabrication of thin film composite (TFC) RO membranes with high performance. However, the reports lacked all the details needed to fabricate a TFC RO membrane, making it difficult to replicate those published fabrication protocols. Based on the efforts of this study, the membrane fabrication procedures utilized did not yield the same quality and performance as reported in these articles. In this study, five TFC RO control membranes were replicated and compared. The membranes produced an average water flux of 21.9 ± 3.6 L/m2h (LMH) and an average salt rejection of 97.6% ± 2.0%. Based on these results, it was concluded that a reproducible fabrication technique was developed for fabricating consistent and reliable TFC RO membranes. Furthermore, this study investigated the role of fouling on TFC RO membrane performance. Enhancing membrane resistance to fouling helps maintain membrane selectivity, lifespan, and permeability. There has been an increasing interest in the modification of the RO membranes for enhanced hydrophilicity, which leads to improvements in fouling resistance. In this study, a positive and high charge density polymer, polyethylenimine (PEI), was introduced into the membrane matrix in varying layers of the membrane structure. PEI-1 was fabricated in-situ by grafting the PEI onto the polysulfone (PSf) support, while PEI-2 was fabricated via grafting of the PEI onto the membrane PA surface. The resulting membranes were characterized using Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), Atomic Force Microscopy (AFM), and Goniometry. PEI-2 produced a more hydrophilic membrane when compared to PEI-1, however, PEI-1 performed better in terms of flux and selectivity. Multiple model foulants were used for investigating the modified membrane fouling performance. These model foulants were tested at varying concentrations, pH values, and with and without the presence of Ca2+ ions. The model foulants used were bovine serum albumin (BSA), sodium alginate, and humic acid. None of the model foulants resulted in a decrease in performance for the membrane over the duration of the tests (up to 13 hours). Future research is needed to develop a robust protocol for testing the fouling of the produced RO membranes within a reasonable timeframe.

Ceramics membranes are made in a wide variety of different techniques using a wide variety of different materials. However, many of the common techniques utilize a slurry of ceramic particles, additives, and either organic solvent or water that is shaped into a membrane, left to dry, and then sintered together. Drying is a time consuming process, often requiring several hours for the liquid medium to evaporate. Defect formation caused by development of partial pressures across the drying membrane, including cracks and warpage, also typically occurs during the drying process. To address this, slurries of ceramic particles made with a low viscosity UV-curable resin, which can cure in the span of a few seconds, eliminating the need for drying and any defects associated with drying. Slurries were made with different particle sizes and volume fractions and made into thin membranes using an Autodesk Ember 3D printer. Curing of UV resin and slurries were examined with FTIR. Pyrolytic behavior of resin was examined using isothermal TGA. Cure depth profiles were determined using the modified Beer-Lambert Law and compared against models in literature. Results showed contrasting curing behavior based on volume fraction and particle size due to differences in UV light exposure methods.

Supramolecular chemistry is the study of discreet molecules assembled into more complex structures though non-covalent interactions such as host-guest effects, pi-pi stacking, electrostatic effects, hydrogen bonding, and metal-ligand interactions. Using these interactions, complex hierarchical assembles can be created from relatively simple precursors. Of the supramolecular interactions listed above, metal-ligand interactions are of particular interest due to the wide possible properties which they present. Factors such as the denticity, polarizability, steric hindrance, ligand structure, and the metal used (among others) contribute to a dramatic range in the physical properties of the metal-ligand complexes. Particularly affected by these factors are the kinetic and thermodynamic properties of the complexes. As a result metal-ligand interactions can vary from inert to extremely transient. Of the vast number of ligands available for study, this dissertation will center on substituted terpyridine ligands, with a particular focus on terpyridine-functionalized polymers. While polymer-functionalized terpyridine ligands and their complexes with transition metals have been heavily studied, the physical properties, particularly the effects of polymer functionalization on the stability of bis complexes of terpyridines, remain unexplored. In the course of investigating the kinetic stability of these complexes, polymer functionalization techniques were developed which were found to increase the stability of the metal-ligand interactions compared to conventional techniques. In addition to studying the effect of terpyridine substituents, the effects of solvent on the stability of the complexes was studied as well. As polymer-bound terpyridine complexes are often studied in solvents other than water, knowledge of the stability of the complexes in organic solvents is important to create supramolecular structures with more precisely controlled properties. It was found that, for unsubstituted terpyridyl complexes, the stability of the complexes varied by as many as five orders of magnitude in common solvents. It is believed that this decrease in stability is the result of the ability of the solvent to facilitate the movement of the ligands from the first and second coordination spheres. Although a large part of this dissertation is dedicated to the study of the kinetic stability of terpyridine complexes, synthetic techniques involving terpyridine and its complexes were investigated as well. It was found that terpyridine functionalized polystyrene could be produced by direction functionalization of terpyridine with polystyryllithium. Additionally heterloleptic terpyridine-based iron complexes were produced with high purity by reduction of the mono terpyridine complex of iron(III) in the presence of a second, functionalized terpyridine ligand. The culmination of these studies was the synthesis of supramolecular organogels, which were crosslinked using metal-terpyridine complexes, yielding dynamic mechanical properties could be broadly tuned by varying the metal used to form the crosslinks.