Dissertations / Theses on the topic 'Copolymers Electric properties'

La plupart des couches d'isolation de câbles pour la moyenne tension "MV" et haute tension "HV" sont fabriquées en polyéthylène réticulé (XLPE) par voie peroxyde. L'impact des sous-produits de réaction sur les propriétés et la nécessité d'une étape de dégazage au cours du processus sont les principaux problèmes liés à cette technologie. Cette étude se concentre sur le développement d'une méthode de réticulation alternative sans les problèmes liés aux sous-produits. Des copolymères d’éthylène/époxy ont été réticulés thermiquement en utilisant un agent aminoacide pour créer des liaisons covalentes entre les fonctions époxydes. L’influence de différents paramètres sur la cinétique de réaction tels que la température de réticulation, les proportions aminoacide/époxy, la taille des particules de l’aminoacide et la teneur en époxy dans les copolymères a été étudiée par techniques de caractérisation telles que : rhéologie dynamique, spectrométrie FTIR, microscopie à balayage électronique et calorimétrie différentielle. En outre, l'étude de la structure du réseau avant et pendant un vieillissement thermique a été effectuée par différentes techniques (mesures de gonflement, spectroscopie FTIR, propriétés de traction et thermoporosimétrie) sur deux types de réseaux : un pré-contraint et un autre non-contraint. Enfin, une caractérisation des propriétés électriques par spectroscopie diélectriques et mesures de claquage électrique a été faite. Les résultats concernant les cinétiques de réaction, les propriétés thermomécaniques et le comportement électrique ont montré que la formulation développée dans cette étude peut être utilisée pour une application de câble
Most of insulation layers of cables for medium voltage “MV” and high voltage “HV” applications are made of crosslinked polyethylene (XLPE) by peroxide technology. The impact of reaction by-products on properties and the consequential need of a degassing stage during the process are the main problems related to this technology. This study focuses on the development of an alternative crosslinking method without by-products issues. Epoxy-ethylene copolymers were thermally crosslinked by using an amino-acid agent to create covalent cross-links between epoxide functions. Influence of several parameters on kinetic reactions such as crosslinking temperature, amino acid/epoxy proportions, size particle of amino acid and epoxy content in copolymers were studied by characterization techniques such as: dynamic rheology, FTIR spectrometry, SEM microscopy and differential calorimetry. In addition, study of the network structure before and during a thermal aging was done on a pre-constrained and a non-constrained network by different techniques (swelling ratio measurement, FTIR spectroscopy, tensile properties and thermoporosimetry analysis). Finally, a characterization of electrical properties by dielectric spectroscopy and breakdown measurements was done. Results related to reaction kinetic, thermo-mechanical properties and electrical behavior have shown that the developed formulation can be used for cable application

A laboratory scale plating cell was built that provided reproducible bottom-up fill results for the electrochemical deposition of copper in damascene features. Several techniques used in the full wafer plating tool were incorporated into the setup to accurately control the process conditions. These techniques included but were not limited to a voltage controlled `hot-entry' step, a custom coupon holder to allow sample rotation, a secondary thief electrode and an automatic entry system. The results of qualification experiments are presented to demonstrate that precise control was realized along with repeatable partial fill plating results. The qualified setup was then used to perform time-evolved partial fill plating experiments using several different structural configurations of open-source suppressors to investigate their affect on the gap-fill characteristics.

Common open-source suppressors used for copper filling of damascene interconnects include polyethylene glycol (PEG), polypropylene glycol (PPG), or a copolymer structure of both. Differences in the configuration and structure of these suppressors generate variations in polarization strength, surface adsorption rate, and SPS displacement rate. These properties were measured by electrochemical transient analysis and coupled with the results of time-evolved partial fill plating experiments to determine the effect of electrochemical property variations on the gap-fill characteristics. The high polarization strength of PPG, along with its greater dependence on concentration was found to greatly increase the bottom-up growth rate during copper filling, while the improved resistance to accelerator displacement of PEG resulted in better sidewall protection. Both these gap-fill characteristics were evident when PEG and PPG were combined together as a mixture of separate homopolymers or in copolymer structures, although the overall influence was dependent on the size and configuration of each component. These data sets provided a more fundamental understanding of PEG, PPG and their different configurations role in the metallization of damascene interconnects. These data can also be used to infer the relative gap-fill performance to screen new suppressor candidates and reduce the quantity of plating experiments by comparison of the electrochemical properties.

This thesis describes the examination of novel block copolymers that contain Ru(bpy)32+ complexes incorporated into one block of diblock copolymers made by ROMP. With the intent of exploring the potential usefulness of these interesting materials in applications such as light-harvesting and sensing, a systematic study of the solution self-assembly, luminescence properties, and the ability of the metal complex to engage in electron and energy transfer reactions has been conducted.
The solution self-assembly of block copolymers that contain Ru(bpy) 32+ complexes was examined first. Using a series of these block copolymers, a detailed study of the effects of block length, block ratio, polymer concentration and solution conditions on the copolymer self-assembly is presented. Using TEM, a number of morphologies were reproducibly observed including star micelles, large compound micelles, tubules, and interestingly, vesicles. These structures all contain the metal complex Ru(bpy)3 2+ within their core domains.
The luminescence properties of two block copolymers containing Ru(bpy) 32+ were examined: one polymer self-assembled into star micelles, the other into vesicles. Comparison of the unassembled polymer chains and the self-assembled polymers indicated that self-assembly, and confinement of the Ru(bpy)32+ complexes into the core domains of the aggregates, did not seriously adversely affect the luminescence properties of the metal complex. Measurement of the luminescence lifetime decay of the polymers suggested that energy migration occurred among the metal complexes along the polymer chain. The ability of the metal complexes within self-assembled structures to participate in electron transfer reactions with small molecules was also explored. It was found that from within the core domains of self-assembled structures, the Ru(bpy)32+ complexes could still engage in electron transfer reactions with molecules on the outsides or the insides of the aggregates, likely a result of energy migration.
The ability of Ru(bpy)32+ complexes within the cores of micelles to participate in energy transfer was explored. Micelles were formed in aqueous solutions using polymers that possessed both the metal complex and a water-soluble block. Several methods were attempted to encapsulate two molecules, a derivative of coumarin 2 and an Os(bpy)3 2+-based molecule, inside these micelles. It was observed that Ru(bpy) 32+ could act as an energy acceptor from the coumarin derivative, and could act as an energy donor to the osmium-based complex. Encapsulation of the small molecules greatly enhanced the efficiency of energy transfer, by non-covalently bringing the small molecules in close proximity to the Ru(bpy)32+ complexes.
Polymers were synthesized that contained a Ru(bpy)3 2+-based block and were terminated with the molecular recognition unit biotin. These polymers, upon self-assembly, formed micelles with biotin groups on their periphery. The addition of the protein streptavidin, which has a strong binding affinity for biotin, resulted in the aggregation of the self-assembled structures. This established the potential for self-assembled metal-containing aggregates to form higher-order structures.
Early work is presented in Appendix A involving block copolymers that contain hydrogen-bonding groups. Several methods were attempted to elucidate the solution morphologies of these polymers, namely IR, 1H NMR, DLS, and pyrene fluorescence. The transition of this initial work to polymers that contain the Ru(bpy)32+ complex is also described.

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Dissertação (Mestrado)
IPEN/D
Instituto de Pesquisas Energéticas e Nucleares - IPEN-CNEN/SP

We performed an in-depth study of high molecular weight poly[3,6-(dithiophene-2-yl)-2,5-di(2-octyldodecyl)-pyrrolo[3,4-c]pyrrole-1,4-dione-alt-thieno[3,2-b]thiophene] P(DPP2OD-TT) synthesized through the Stille coupling polycondensation in order to understand the correlation between molecular weight, processing conditions and charge transport. We observed a rapid increase in its aggregation in solution with increasing molecular weight which strongly limits the solubility and processability for weight average molecular weights beyond 200 kg mol⁻¹. This results in severe limitation in the charge transport properties of the polymer. We further observe the presence of bulk electronic defects in all different polymer batches that severely limit the current flow and manifest themselves in organic field effect transistors as apparent charge density dependence of the mobility. These defects are passivated by exposure to an ambient atmosphere, as confirmed by an increase in current and mobility that is no more charge density dependent. This is further confirmed by the result of chemical doping using 2,2-(perfluoronaphthalene-2,6-diylidene)dimalononitrile, F₆TCNNQ, which leads to the filling of the trap states and a higher charge density independent mobility of up to 1 cm2 V⁻¹ s⁻¹.

The semiconducting properties of a bithiophene-naphthalene diimide copolymer (PNDIT2) prepared by Ni-catalyzed chain-growth polycondensation (P1) and commercially available N2200 synthesized by Pd-catalyzed step-growth polycondensation were compared. Both polymers show similar electron mobility of [similar]0.2 cm2 V−1 s−1, as measured in top-gate OFETs with Au source/drain electrodes. It is noteworthy that the new synthesis has several technological advantages compared to traditional Stille polycondensation, as it proceeds rapidly at room temperature and does not involve toxic tin-based monomers. Furthermore, a step forward to fully printed polymeric devices was achieved. To this end, transistors with PEDOT:PSS source/drain electrodes were fabricated on plastic foils by means of mass printing technologies in a roll-to-roll printing press. Surface treatment of the printed electrodes with PEIE, which reduces the work function of PEDOT:PSS, was essential to lower the threshold voltage and achieve high electron mobility. Fully polymeric P1 and N2200-based OFETs achieved average linear and saturation FET mobilities of >0.08 cm2 V−1 s−1. Hence, the performance of n-type, plastic OFET devices prepared in ambient laboratory conditions approaches those achieved by more sophisticated and expensive technologies, utilizing gold electrodes and time/energy consuming thermal annealing and lithographic steps
Dieser Beitrag ist aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich

New hybrid materials from the grafting of polystyrene on the surface of nitrogen doped carbon nanotube were synthesized. These chemically modified nanotubes were further used in the fabrication of polymer based nanocomposites. In these works, we studied the impact of the polymer grafted nanotubes on the electrical and mechanical properties of a polystyrene (PS) and a poly (butadiene-co-styrene) (PSBS) matrices. The grafted nanotubes have a better dispersion in a PS matrix as compared to the as received ones. Nevertheless, this kind of functionalization does not lower the percolation threshold since the grafted polymer layer electrically isolates the nanotubes each others. On the other hand, the mechanical reinforcement (PS matrix) increases when the nanotubes are polymer grafted. Furthermore, a stronger mechanical reinforcement is observed for large strain deformation. Concerning the nano-structured PSBS matrix, we observed a stronger mechanical reinforcement as compared to the PS matrix. The PS grafted nanotubes permit to connect the PS nano-domains of the matrix and consequently forms a percolating rigid network with a very low threshold (PC<0. 05 vol. %)
ADes nouveaux matériaux hybrides, provenant du greffage de polystyrène à la surface de nanotubes de carbone dopés azote (CNx MWNTs) ont été synthètisés et utilisés dans l’élaboration de nano-composites à matrice polymère. Dans ces travux de recherche nous avons étudiés l’impacte de ces nanotubes de carbone greffés polystyrène sur les propriétés mécaniques et électriques de matrices polystyrène (PS et poly (butadiène-co-styrène) (PSBS). Les nanotubes greffés ont une meilleure dispersion dans une matrice de polystyrène que les nanotubes sans traitement chimique. Cependant, ce type de fonctionnement ne permet pas de baisser le seuil de percolation électrique, puisque le greffage tend à isoler électriquement les nanotubes. Par ailleurs, nous avons observé une sensible augmentation de l’effet de renfort mécanique de la matrice PS quand les tubes sont greffés ; particulièrement quand les composites sont soumis à de grandes déformations. Dans le cas particulier d’une matrice nano structurée comme le PSBS, nous avons observé un effet de renfort mécanique beaucoup plus important quand les nanotubes étaient greffés. En effet, la couche de PS à la surface des CNx MWNTs connecte les domaines de PS du copolymère, permettant l’apparition d’un réseau percolant rigide avec un seuil de percolation très bas (PC <0. 05 vol%)

This research investigates the synthesis and manufacture of shape-memory polymer (SMP) systems for use in biomedical and commodity applications. The research centers on improving the mechanical properties of thermoset acrylate copolymers with memory properties at reasonable cost through various design and manufacturing techniques: high-strain polymer synthesis and radiation crosslinking. The research assesses combinations of linear monomers and a low density of crosslinker to characterize new functional materials and optimize emerging mechanical properties such as the glass transition temperature (Tg) and rubbery modulus (ER). Exploring materials with large recoverable strains, a model copolymer of photo-polymerized methyl acrylate (MA), isobornyl acrylate and crosslinker bisphenol A ethoxylate dimethacrylate was shown to strain above 800%, twice the previously published value for SMPs, and recover fully. In the quest to maximize fully recoverable strains, a new hybrid molecule nicknamed Xini, which serves as both an initiator and a crosslinker, was also theorized, synthesized, polymerized into SMP networks and characterized. In the past, thermoset SMPs were made into complex shapes using expensive top-down techniques. A block of polymer was made and custom machining was required to craft complex parts. This prohibited devices in cost-competitive commodity application spaces. This research has proposed and validated a new method for accurately tuning the thermomechanical properties of network acrylates with shape-memory properties: Mnemosynation, eponymously named for the Greek goddess of memory. This novel manufacturing process imparts long term 'memory' on an otherwise amorphous thermoplastic material utilizing radiation-induced covalent crosslinking, and can be likened to Vulcanization, which imparts strength on natural rubber utilizing sulfur crosslinks. Adjustment of ER in the range from below 1 MPa to above 13 MPa has been demonstrated. ER was tailored by varying both radiation dose between 5 and 300 kGy and crosslinker concentration between 1.00 and 25.0 wt%. Tg manipulation was demonstrated between 23 ˚C and 70 ˚C. Mnemosynation combines advances in radiation grafting and acrylic SMP synthesis to enable both traditional plastics processing (blow molding, injection molding, etc.) and control of thermoset shape-memory properties. Combining advances in both high strain polymer synthesis and radiation crosslinking, a new paradigm in SMP composites manufacture-namely, that materials can be designed to enhance strain capacity at moderate stress, rather than maximum strength-was established. Various fibers with very different mechanical properties were impregnated with SMPs and thermo-mechanically assessed to develop an understanding of the technical parameters necessary to craft self-adjusting, multi-actuated, SMP-fiber composite orthopedic casts. This exploration syncs with the overarching aim of the research, which is to understand the fundamental scientific drivers necessary to enable new devices mass-manufactured from acrylate copolymers and optimize their emerging mechanical properties.

Le travail présenté ici porte sur la réalisation d’un matériau polymère piézoélectrique destiné à être l’élément sensible d’un capteur de déformation de tissus biologiques. Cela comprend notamment l’étude de l’assouplissement du copolymère P(VDF-TrFE) nécessaire pour se rapprocher des propriétés mécaniques d’une artère, sans dégrader son coefficient piézoélectrique. Des films de P(VDF-TrFE) plastifiés avec du phtalate de diéthyle (DEP) ont été réalisés selon différents protocoles incluant enduction ou spin-coating et polarisation sous haute tension pour activer les propriétés ferroélectriques. Selon les conditions d’élaboration, deux structures distinctes de films ont été obtenues avec des propriétés physiques propres à chacune. Dans le premier type de film, l’étude de la morphologie et des courbes d’hystérésis polarisation-champ électrique a permis de mettre en évidence une nouvelle structuration du matériau, avec la démixtion du plastifiant dans la matrice. Le champ coercitif est dans ce cas fortement abaissé ce qui permet une réduction de la haute tension de polarisation nécessaire allant jusqu’à 40%, même lorsque que le film ne contient plus que 50wt% de P(VDF-TrFE). Le second type de film, obtenu après recuit à plus basse température, présente au contraire une structure quasi homogène et des propriétés proches d’une loi de mélange. Le champ coercitif reste comparable à celui du P(VDF-TrFE) pur mais la flexibilité du matériau est fortement accrue. L’étude des propriétés mécaniques a montré que le plastifiant peut réduire le module de Young du copolymère à 40MPa avec 30wt% de DEP dans le film. De surcroit la polarisation rémanente et le coefficient piézoélectrique sont également renforcés. Des tests in vitro et in vivo, réalisés sur des artères, de capteurs basés sur ces derniers films ont démontré le haut potentiel du matériau à détecter des déformations de tissus mous et à fonctionner aux fréquences biologiques humaines
The work presented here focuses on the preparation of a piezoelectric polymer material aimed to be the sensitive element of a strain sensor of biological tissues. This includes the study of the softening of the copolymer P(VDF-TrFE) necessary to be close of the mechanical properties of an artery, without reducing the piezoelectric coefficient. Plasticized P(VDF-TrFE) films with diethyl phthalate (DEP) were made according to different protocols including doctor blade technique or spin-coating and polarization under high voltage to activate the ferroelectric properties. Depending on the preparation conditions, two distinct structures were obtained with physical properties specific to each of them. For the first type of film, the study of the morphology and the hysteresis loops polarization-electric field showed a new structure of the material, with a demixing of the plasticizer in the matrix. In this case, the coercive field is strongly reduced which allows a decrease of the required high polarization voltage up to 40%, even if the film only contains 50wt% of P(VDF-TrFE). The second type of film, obtained after an annealing at lower temperature, has an almost homogeneous structure and properties close to a mixing law. The coercive field remains comparable to that of the pure P(VDF-TrFE) but the flexibility of the material is greatly increased. The study of the mechanical properties showed that the plasticizer can reduce the Young modulus to 40MPa for 30wt% of DEP in the film. In addition, the remanent polarization and the piezoelectric coefficient are also reinforced. In vitro and in vivo experiments, performed on arteries, of sensors based on these films demonstrated the high potential of the material to detect the strain of soft tissues and to function at biologic human frequencies

碩士
國立臺北科技大學
化學工程研究所
96
Polyfluorene is a well known hole-transporting material with high mobility. Attempts have been made to improve the electron-transport and hole-transport properties of polyfluorenes by introducing electron-donor and electron-acceptor moieties, respectively. In part A, we synthesized two fluorene-based copolymers through the incorporation of electron donor triphenylamine and electron acceptor 1,2,4-triazole moieties group into the polymer backbone. The PTPATAZ-F8 and PTAZTPA-F8 copolymers exhibited good thermal stability with 5％ loss weight temperature of 403℃ and 411℃, and the glass transition temperatures of 135℃ and 185℃, respectively. The emission maxima of copolymer films on the photoluminescence spectra were 413-435 nm, which corresponded to blue color. From electrochemical results, PTPATAZ-F8 containing triphenylamine main chain showed high ionization potential（HOMO=-5.31） than PTAZTPA-F8（HOMO=-5.72）. Electroluminescence device with the configuration of ITO/PEDOT：PSS/ PTPATAZ-F8/LiF/Al was fabricated to evaluate the potential EL application. The device using PTPATAZ-F8 as the active layer showed EL performance with max emission band at 444nm and turn-on voltage at 6V. The maximum luminance was 84 cd/m2 and the maximum luminance efficiency was 0.044 cd/A. The CIE’ 1937 coordinate was located at（0.160, 0.130）. In part B, we used the monomers in port A through the incorporation electron acceptor 2,1,3-benzothiadiazole into the polymer backbones. The PTPATAZBT-F8 and PTAZTPABT-F8 copolymers exhibited good thermal stability with 5％ loss weight temperatures of 433℃ and 406℃, and the glass transition temperatures of 155℃ and 153℃, respectively. The emission maxima of copolymer films on the photoluminescence spectra were 541-547 nm, which corresponded to yellow-green color. From electrochemical results, the HOMO level of PTPATAZBT-F8 and PTAZTPABT-F8 showed the same as part A. The device using PTPATAZBT-F8 as the active layer showed best EL performance with max emission band at 542nm and turn-on voltage at 5V. The maximum luminance was 696 cd/m2 and the maximum luminance efficiency was 2.02cd/A. The CIE’ 1937 coordinate was located at（0.345, 0.625）.

碩士
國立臺灣科技大學
高分子系
95
This paper explores the applicability of blended cyclo olefin copolymer films containing doping cationic photo initiator in the direct methanol fuel cell operating environment. Experimental tensile strength measurements were used to analyze the dynamic properties of the films, and yielded the finding that dynamic response fell with increasing concentration of photo initiator. A scanning electron microscope was used to perform state observations and elemental analysis; it was found that the ratios of the elements iodine, sulfur, and fluorine increased after illumination, but decreased sharply after water washing. A thermo gravimetric analyzer was used to observe the thermal decomposition process of blended films, and revealed that the decomposition temperature of the film was as high as 460°C, while the photo initiator had a decomposition temperature of 250°C. This indicates that blended films have sufficient thermal stable for use in direct methanol fuel cell systems. Use of an AC resistance meter revealed that both conductance and moisture content increased as photo initiator was added. This shows that addition of a photo initiator can help increase proton transmission properties. The conductance and moisture content of a test plate also both increased after illumination. As for methanol permeability, the ASTM E96 steam permeability test method was used to measure the diffusion of fumes from a methanol-water solution in the film. In addition, an Abbe refractometer was used to measure the concentration of the methanol-water solution used in the previous experiment and gain a better understanding of the film's ability to block methanol molecules. It was found that the diffusion of methanol-containing steam decreases with increasing photo initiator concentration, and also shown that the concentration of the methanol-water solution remaining after the experiment increases with photo initiator concentration. It was revealed that test plates with high photo initiator concentration have good ability to block methanol molecules. Finally, test plates were uniformly better able to block both methanol molecules and steam containing methanol after illumination.

Tese de doutoramento (Programa Doutoral em Engenharia de Materiais)
Composites are an important class of materials as they allow to reinforce or to include specific properties not typically found in nature. In this way, suitable electromechanical materials allow the measurement of large deformations by electrical means can be achieved by the development of composites. Research in electromechanical composites has been based in several polymer matrices with carbon nanoallotropes to increase the electrical conductivity of the composites. Successful development of electromechanical transducer materials has been accomplished, but reliable solutions for the development of large deformation sensors are still to be developed to meet the increasing industrial needs. This work is focused on the study of the electromechanical response of carbon nanotubes/thermoplastic elastomers (CNT/TPE) composites with the main goal of maximizing sensitivity and deformation (> 30%) in order to improve the application range of the composites for sensor applications. The composite materials used in these work are four different tri-block copolymers styrene-butadiene-styrene (SBS) (with reference C401, C411, C500 and C540) where the block copolymer structure is linear or radial and butadiene/styrene ratio ranged between 80/20 to 60/40. The composites materials are prepared by three different processing methods: solvent casting, extrusion and electrospinning. The amount of CNT included in the composites prepared by the different processing methods are 0, 1, 2, 4 and 8 weight percentage (wt%) for solvent casting, 0, 2, 4, 6, 8 and 10 wt% for extruded composites and 0, 0.05, 0.1 and 0.5 wt% for electrospun composites. It was important to find the electrical percolation threshold to obtain suitable electromechanical responses for sensors applications. Different types of CNT such as single walled CNT (SWCNT) and multi walled CNT (MWCNT) were used to study electrical and electromechanical properties of the composites. Chemical treatment of the CNT was also performed to understand the effect of functionalization on CNT dispersion and in the electromechanical response of the CNT/SBS composites. Covalent and non-covalent functionalization on MWCNT has been used for filler concentrations up to 8 wt%. SBS shows maximum strain larger than 1000% both for pure SBS and the both composites prepared by solvent casting and extrusion. On the other hand, composites prepared by electrospinning show a maximum strain of 350%. The ratio of butadiene/styrene in the copolymer and the different copolymer architecture mainly influences the mechanical properties. Initial modulus is larger for matrices with higher amounts of styrene and for CNT/SBS composites increases with increasing CNT content, independently of the composite processing method. Mechanical hysteresis of the composite increases with applied strain (from 5% to 20%) and decreases with increasing the number of stress-strain cycles. Softer matrices (higher amount of butadiene) have lower mechanical hysteresis than harder matrices (higher amounts of styrene), demonstrating the influence of the butadiene/styrene ratio on the mechanical properties of the composites. Morphological evaluation of the composites shows well dispersed clusters of CNT inside SBS matrices for pristine CNT and individual dispersion of functionalized CNT within the SBS matrices. The percolation theory concludes that hopping between nearest fillers is considered as the main mechanism for the composite electrical conduction, the overall composite conductivity is explained by the existence of a weak disorder regime. The amount of pristine CNT inside the SBS matrix improves electrical properties of the composites, the electrical percolation threshold being lower than 1 wt% CNT for composites prepared by solvent casting and electrospinning processing methods, increasing up to 4-5 wt% CNT content for extruded composites. Composites with covalent and non-covalent functionalization, do not present electrical percolation threshold for filler contents up to 8 wt% CNT, where conductivity remains similar to pure SBS matrix. The electromechanical properties of the composites depend on composite fillers content, CNT functionalization state and processing methods. Uniaxial strain and 4-pointbending measurements for solvent casting composites show larger electromechanical response for all matrices with maximized sensibility after initial pre-stress. The Gauge Factor (GF) for solvent casted composites with 4 wt% CNT filler content can reach values of GF~120 for C540 samples under uniaxial strain and GF~100 for C401 samples under 4-point-bending mechanical solicitation. For extruded composites with 8 wt% CNT, they reach a value of ~30 for C401 SBS under uniaxial strain. The maximum deformation with suitable electromechanical response can reach 50% of strain. The proof of concept of the composites for sensor applications has been performed with the development of a glove with finger movement monitoring.
Compósitos são atualmente uma importante classe em materiais e possibilitam obter propriedades únicas não presentes na natureza. Seguindo esta ideia, podem ser desenvolvidos materiais com propriedades electromecânicas para medir grandes deformações mecânicas através da resposta elétrica. A procura destes compósitos eletromecânicos é baseada em diversas matrizes poliméricas com o reforço dos diversos nanomateriais carbonáceos. O presente trabalho é focado no estudo da resposta eletromecânica de compósitos nanotubos de carbono/termoplásticos elastómeros tendo como objectivo principal maximizar a sensibilidade eletromecânica e a deformação (> 30%), alargando o leque de aplicações destes compósitos. Os materiais utilizados neste trabalho são quatro diferentes copolímeros de estirenobutadieno- estireno (com a referencia C401, C411, C500 e C540), utilizados como matriz, tendo o copolímero estrutura linear ou radial e rácio butadieno/estireno varia entre 60/40 e 80/20. Como material de reforço são usados três diferentes tipos de nanotubos de carbono, de parede simples ou múltipla com a referência C150P, NC7000 e AP-SWNT. Os compósitos foram preparados por três métodos: a partir da dissolução num solvente, por electrospinning e extrusão. A quantidade, em massa, de nanotubos de carbono presente nos compósitos foi de 0, 1, 2, 4 e 8% para o processamento a partir da solução, de 0, 2, 4, 6, 8 e 10% para o processamento por extrusão, e de 0, 0.05, 0.1 e 0.5% para os materiais processados por electrospinning. As várias concentrações foram utilizadas de forma a determinar o limite de percolação elétrico dos compósitos, de forma a otimizar a resposta eletromecânica destes. Os nanotubos de carbono também foram alvo de funcionalização, covalente e não-covalente, com o intuito de entender a evolução das propriedades dos compósitos com os diferentes nanotubos e funcionalizações destes. Compósitos até 8% em massa de nanotubos foram processados a partir de um solvente com nanotubos de carbono funcionalizados. As matrizes poliméricas apresentam excelentes propriedades mecânicas com a deformação máxima a variar entre 350% para os materiais processados por electrospinning e mais de 1000% para os compósitos preparados com os restantes tipos de processamento. O rácio butadieno/estireno influencia essencialmente as propriedades mecânicas e o módulo elástico aumenta com a quantidade de estireno e de nanotubos de carbono na matriz, independentemente do processamento utilizado. A histerese mecânica aumenta com a deformação e diminui com o número de ciclos tensãodeformação aplicados no compósito, sendo maior para as matrizes com maior quantidade de estireno no copolímero. A morfologia dos compósitos é similar para os nanotubos de carbono sem tratamento, apresentando uma boa dispersão de agregados de nanotubos de carbono. Os compósitos com os nanotubos de carbono funcionalizados apresentam uma dispersão individual de nanotubos de carbono em vez de uma dispersão de agregados. A teoria da percolação mostra que o hopping entre os nanotubos vizinhos é considerado o principal mecanismo de condução elétrica no compósito, e a condutividade total do compósito pode ser explicada pela existência de um regime de fraca desordem. O aumento de nanotubos de carbono não funcionalizados na matriz polimérica melhora as propriedades elétricas do compósito sendo o limite de percolação elétrico menor que 1% em massa para os compósitos processados a partir do solvente e por electrospinning e cerca de 4-5% para os compósitos processados por extrusão. Os compósitos usando nanotubos de carbono funcionalizados não apresentam percolação elétrica. As propriedades eletromecânicas do compósito dependem da quantidade de nanotubos de carbono na matriz e do método de processamento. As medidas para a deformação unidireccional e a flexão de 4 pontas para compósitos processados a partir de solução no solvente apresentam uma boa resposta eletromecânica para as quatro matrizes poliméricas, tendo a sua sensibilidade maximizada após pré-deformação. O Factor de Gauge para os compósitos com 4%, em massa, de nanotubos de carbono é cerca de 120 e 100 para a matriz C540 medida pelo método de deformação unidireccional e de flexão de 4 pontas, respectivamente. Para compósitos processados por extrusão, com 8% em massa, o Factor de Gauge máximo é cerca de 30, para a matriz C401 medido na deformação unidireccional. A deformação máxima com uma boa resposta eletromecânica é de 50% nestes compósitos. A prova de conceito da utilização destes compósitos para aplicações de sensores foi realizada através do desenvolvimento de uma luva com a monitorização do movimento dos dedos.

碩士
國立中央大學
化學研究所
92
Abstract A novel series of conjugated copolymers comprising alternating π-excessive alkylthiophene (or bis(3-octylthiophene)) and π-deficient 2,6-pyridine (or 3,8- phenanthrolin) moieties were synthesized using a palladium-catalyzed Stille coupling reaction or Nickel-catalyzed Suzuki coupling reaction. They are characterized by 1H-NMR, FT-IR, ESCA, EA, gel permeation chromatography(GPC), thermogravimetric analysis(TGA), differential scanning calorimeter (DSC), UV-Vis absorption, fluores- cence spectroscopies, and time-resolved photoluminescence spectroscopy (TR-PL). These copolymers were highly soluble in common organic solvents and showed good thermal stability. The electronic and optical properties of these copolymers were closely related to the structures of the polymer backbone. Copolymers containing 2,6-pyridine or 3,8- phenanthrolin moieties not only exhibited blue shifts in UV-Vis absorption and fluorescence spectra but also enhanced the quantum yield significantly compare to their thiophene analogues. The λmax of poly-3-octylthiophene derivatives underwent a blue shift and intensity decreasing with increasing temperature. This thermochromic behavior was reversible. The quantum efficiency of copolymers containing 3,8- phenanthrolin increased with increasing solvent polarity, from less polar toluene to highly polar NMP. TR-PL spectra revealed that copolymers contained pyridine moiety will have a longer life time and therefore higher quantum efficiency. A single layer PLED devices was fabrication by using POTPyOT as a luminescence layer demonstrated that these novel copolymers might be promising materials for applications in light-emitting diodes.

The work carried out in this thesis systematically investigates the correlation between microstructures and electronic properties of organic semiconductors. The major directions that were pursued in this thesis are: (i) studies on structure-property relationship by rational design and synthesis of monodisperse oligomers with varying chain-lengths (ii) role of electronic properties and aggregation (microstructures) in governing singlet fission (SF). In the first part of the thesis, the optical, structural and charge transport properties of Diketopyrrolopyrrole (DPP)-based oligomers, as a function of the chain length, has been discussed. The energy bands became wider with an increase in chain length and a gain in backbone electron affinity was observed, with an offset in microstructural order. With an increase in chain length, the tendency to form intramolecular aggregates increased as compared to intermolecular aggregates due to the onset of backbone conformational defects and chain folding. An insight into the solid-state packing and microstructural order has been obtained by steady-state and transient spectroscopy, grazing incidence small angle x-ray scattering (GISAXS), atomic force microscopy (AFM) and transmission electron microscopy (TEM) studies. The charge-carrier mobilities varied in accordance with the degree of microstructural order as: dimer > trimer > pentamer. A library of DPP-DPP based trimers was also generated by modifying the donor chromophore (phenyl, thiophene and selenophene) in the oligomer backbone. Highest n-channel mobility of ~0.2 cm2V-1s-1 was obtained which validated that: (a) the effect of solid-state packing predominates the effect of backbone electronic structure on charge carrier mobility. Although oligomers possess lesser backbone defects than polymers in general, their charge carrier mobilities were not comparable to that of 2DPP-OD-TEG polymer, which forms highly oriented and isotropic edge-on crystallites/microstructures in the thin film, shows high n-channel mobility of 3 cm2V-1s-1 and band-like transport ;(b) although delocalized electronic states are achieved at greater chain lengths, the degree of solid-state microstructural order drastically reduces which leads to lower charge carrier mobilities; (c) conformational collapse resulted in lower electron mobilities and an increase in ambipolarity. The later part of the thesis debates on the relative contribution of electronic structure and aggregation (microstructures) in governing singlet fission (SF). Motivated by the recent SF model in carotenoid aggregates, a DPP-DPP based oligomer was synthesized by incorporating a vinylene bridge to imbue “polyene” character in the chromophore. Transient Spectroscopy (TA) measurements were carried out to monitor the formation of triplet states in the oligomer and to probe the occurrence of singlet fission. Although the oligomer exhibits “polyene” character like a typical “carotenoid aggregate”, it did not show singlet fission because of the additional stabilization of the singlet (S1) state which reduces the ∆EST. This study rationalized the importance of judicious control of band structures as well as microstructures to observe the SF phenomenon in this category of chromophores. The novel synthetic protocol provides the scope to tailor DPP-DPP based materials with desired effective conjugation lengths and side chains and can foreshow great prospects for future generation of organic electronics.

碩士
國立臺灣大學
高分子科學與工程學研究所
94
Abstract The electronic structures and electronic properties of conjugated polymers have been tuned by modifying the chemical structures in many studies for specific aims. In this study, we divide two parts to discuss: (A) theoretical analysis on the geometries and electronic properties of acceptors-based poly(heteroarylene methine)s, and (B) synthesis the fluorene-based copolymers with donor-acceptor-donor systems(1:1) and their application on the thin-film transistors. In the PART A of this study, a comprehensive understanding on the relationship between theoretical geometries and electronic properties of acceptor-based poly(heteroarylene methine)s was explored by the density functional theory (DFT) at the B3LYP level with 6-31G basis set. The optimized geometries: bond length alternation and dihedral angle were investigated and correlated with the electronic properties: HOMO, LUMO, band gap and bandwidth. The results suggested that poly(heteroarylene methine)s had smaller band gap relative to the their homopolymers, due to the coexistence of aromatic and quinoid form and the lower LUMO energy levels. The geometries of these poly(heteroarylene methine)s were significantly affected by the fused ring size, side groups, and heteroatoms. The electronic properties of HOMO, LUMO, band gap and bandwidth were significantly controlled by the dihedral angle, bond length alternation, and the acceptor strength. The smaller bond length alternation and stronger acceptor strength result in the smaller band gap. In the PART B of this study, we synthesize the fluorene-based donor-acceptor-donor copolymer for thin film transistor applications. The copolymer was synthesized through the palladium-catalyzed Suzuki coupling reaction. The optical and electrochemical properties of PFO-DTTP determined by UV-vis and CV suggest small band gaps of 1.82 and 1.67 eV, respectively, due to the strong intramolecular charge transfer. Beside, the thin film transistor device fabricated by PFO-DTTP in DCB has field-effect mobility of 1.38*10-5 cm2/(Vs) and the maximum on/off ration observed of 5.91*103, which is slightly higher than the common TFT materials of F8T2. It suggests the significance of intramolecular charge transfer on the transistor characteristics.