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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Synthesis of Polythiophene Derivatives on the Application of Electro-Optical Devices

Pan, Jhong-Yu 19 August 2010 (has links)
Regioregular poly(3-alkylthiophenes) is a kind of conjugated polymers with HT-coupled structures . P3HT(head-to-tail) can be easy to access a low energy and low space obstacle coplanar conformation that leads to highly conjugated polymer , better conductivity and optical properties. In this research, we found out the different way of synthesis led to differences in properties such like regioregular, molecular weight. Above mentioned would influence spectrum of materials and device morphology. We chosen three kind of methods easily to synthesize from papers included FeCl3 Method, Grignard metathesis methods(Methylmagnesium bromide¡BTert-butylmagnesium chloride). We observed the different synthetic methods we used led to different reaction and color. After the analysis, there are not only differences between regioregular and molecular weight but molecular conformation. We also noted there were some residues that could not be completely removed by ion in the polymerization process. Absorption spectrum of film is shifted showed it has different degrees of phase separation. The literature tell us that the molecular weight greatly influences the device efficiency, because it changes the morphology and that affects the mobility and Regioregular. In this study, another field of research discusses the impact of ion. It was found after polymerization. The product not clean in the absorption spectrum of performance does not meet the solar cell requirements. After washing, it couldn¡¦t wash away the small amount of residue ion Fe, Mg, Ni, and it¡¦s about 1 ~ 3% in the total material. The experiment shows the various characteristics of different materials leads to change in device efficiency. Among them, the devices have the high molecular weight and good regioregular have the higher efficiency.
2

The Physical and Spectroscopic Study of a Series of Poly(3-hexyl thiophene) Homopolymers and Poly(3-hexyl thiophene)-block-Poly(2-hydroxyethyl methacrylate) Diblock Copolymers

Peng, Qiliang 31 March 2010 (has links)
In block-selective solvent, the rod-coil block copolymers can form various micellar structures. With block copolymers that contain a conjugated polymer block, the conformation of the conjugated polymer can be reflected by spectral changes in the solution. Therefore, it is of interest to study the relationship between the spectral changes and the nature of the conjugated polymer. The fundamental physical properties of poly(3-hexyl thiophene) (P3HT) were studied. Five P3HT samples with different molecular weights were used. We have determined the relationship between physical and spectral properties of this polymer and its molecular weight. In particular, we have found that the refractive index increments, the maximum absorbance wavelength, extinction coefficients, and the emission wavelengths, increase with molecular weight. Diblock copolymers of poly(3-hexyl thiophene)-block-poly(2-hydroxyethyl methacrylate) (P3HT-b-PHEMA) were also studied. The morphological and spectral changes of these block copolymers were studied at various stages of micelle formation in block selective solvents. The relationship between the volume fraction of the P3HT block and their physical and spectral properties were also discussed. / Thesis (Master, Chemistry) -- Queen's University, 2010-03-31 11:30:44.539
3

PROCESS DEVELOPMENT FOR THE PRODUCTION AND SEPARATION OF MEDIUM-CHAIN-LENGTH POLY(3-HYDROXYALKANOATES) BY PSEUDOMONAS PUTIDA KT2440

JIANG, XUAN 31 August 2010 (has links)
A series of medium-chain-length poly(3-hydroxyalkanoates) (MCL-PHAs) with enriched 3-hydroxynonanoate (HN) content (up to 95.8 mol% compared to 68.6 mol% without acrylic acid) or 3-hydroxyoctanoate (HO) content (up to 97.5 mol% compared to 88.0 mol% without acrylic acid) was produced in continuous culture by co-feeding fatty acid and glucose plus inhibiting fatty acid β-oxidation using acrylic acid. Using a similar feeding strategy in fed-batch fermentation, similar monomeric compositions but a higher biomass concentration and PHA content could be obtained. However, at a lower growth rate (0.15 h-1 vs. 0.25 h-1), the biomass concentration and PHA content could be greatly enhanced from 17.1 to 71.4 g L-1 and from 64.4 to 75.5%, respectively, while the HN content decreased slightly from 92.2 to 88.9 mol%. PHAs produced under acrylic acid inhibition possessed improved physical properties including a higher melting point, faster crystallization rate, and greater tensile strength at break and Young’s modulus. Two recovery methods were developed for the recovery of MCL-PHA from Pseudomonas putida KT2440. One applied acetone extraction which was capable of recovering all the PHA from the cells with a purity of 91.6% and no detectable polymer molecular weight loss using Soxhlet extraction. Further purification was achieved by redissolving in acetone and reprecipitating in cold methanol. The other method used sodium hydroxide to solubilize the non-PHA cellular material. PHA purity of about 85% was obtained from a biomass containing 65.6% PHA after treatment with 0.2 N NaOH at 22 ± 1oC for 2 h or with 0.1 N at 80 ± 1oC for 15 min. However, a treatment at 22 ± 1oC followed by a second NaOH treatment at 80 ± 1oC resulted in higher PHA purity (94.7%) with a recovery efficiency of 88%. Under these conditions, NaOH digestion had a negligible effect on PHA molecular weight. / Thesis (Ph.D, Chemical Engineering) -- Queen's University, 2010-08-30 22:44:44.501
4

Nanocomposites polythiophènes/nanotubes de carbone alignés : élaboration, caractérisations et applications aux supercondensateurs en milieu liquide ionique / Nanocomposites polythiophene/aligned carbon nanotubes : elaboration, characterizations and applications for energy storage (supercapacitors) in Ionic liquid

Lagoutte, Sébastien 22 October 2010 (has links)
Le présent travail a porté sur l’élaboration d’électrodes à base de polymère conducteur et d’un tapis de nanotubes de carbone alignés pour les applications de supercondensateur.Dans la première partie de ce travail, nous avons porté notre attention sur le choix de nos matériaux et nous avons pu déterminer leur comportement électrochimique en milieu liquide ionique. Les deux polymères choisis : le poly(3-méthylthiophène) et le poly(3,4-diméthylthiophène) possèdent des propriétés très différentes en terme de capacitance, de potentiel d’oxydation, de résistance ou de cyclabilité. Afin d’allier ces propriétés entre elles, nous avons réalisé la synthèse de copolymères obtenus par voie électrochimique en milieu liquide ionique aprotique. Cette électro-co-polymérisation nous a permis d’obtenir une large gamme de matériaux aux propriétés variables selon la composition du polymère.Dans la deuxième partie de ce travail, nous avons optimisé la synthèse électrochimique d’un nanocomposite poly(3-méthylthiophène)/nanotubes de carbone alignés en milieu liquide ionique. Les matériaux obtenus offrent la propriété d’être « auto-supportés » et permettent ainsi de s’affranchir de collecteur de courant. La nanostructuration grâce aux nanotubes et l’absence de collecteur de courant nous ont permis d’améliorer d’un facteur 3 la capacitance spécifique de nos électrodes. Une optimisation des conditions d’élaboration des nanocomposites permettent d’atteindre une capacitance de 180F.g-1 dans EMITFSI à 30°C. / The present work concerned the elaboration of electrodes containing electronic conducting polymer and a carpet of aligned carbon nanotubes for supercapacitor applications. In the first part of this work, we put our attention on the choice of our materials and we were able to determine their electrochemical behavior in ionic liquid. Both chosen polymers : poly(3-méthylthiopène) and poly(3.4-diméthylthiophène) possess very diffrent properties in term of capacitance, oxidation potential, resistance or cyclability. In the second part of this work, we optimized the electrochemical synthesis of a nanocomposite poly(3-méthyltiophène)/aligned carbon nanotubes in ionic liquid. The obtained materials offer the property to be "self-supported" and allow using themselves without current collector. And optimization of the conditions of nanocomposites elaboration allows reaching a capacitance of 180 F.g-1 in EMITFSI in 30°C.
5

Roubování VTMOS na PHB / Grafting VTMOS onto PHB

Novotný, Igor January 2018 (has links)
Diploma thesis deals with the grafting of vinyltrimethoxysilane (VTMOS) onto poly(3–hydroxybutyrate)PHB. Subsequent characterization of the amount of grafted VTMOS and changes in the thermal properties associated with the rate of crystallization. The theoretical part deals with mechanism and the influences of grafting. In the experimental part VTMOS was grafted onto PHB without subjecting VTMOS to hydrolysis and subsequent crosslinking. By differential scanning calorimetry (DSC) and Avrami equation, the effect of grafted silane group on pure was studied. The MVR was used to compare the rheological properties of initial PHB, grafted PHB and crosslinked PHB by siloxane linkages.
6

Mikrovlákna na bázi polyhydroxybutyrátu pro medicínské aplikace / Microfibers based on polyhydroxybutyrate for medical applications

Gregušková, Zuzana January 2021 (has links)
Diplomová práca je zameraná na mikrovlákna na báze biopolyméru poly(3-hydroxybutyrátu) a ich využitie v medicínskych aplikáciách. Teoretická časť práce sa zaoberá štúdiom procesu tvorby vláken pomocou technológie odstredivého zvlákňovania, jeho kinetikou a faktormi ovplyvňujúcimi vznik a vlastnosti vláken. Teoretická časť sa následne orientuje na krátky prehľad biopolymérov používaných v tejto technológii, charakteristiku materiálu poly(3-hydroxybutyrátu) a taktiež prezentuje návrh potenciálnej cieľovej aplikácie daných mikrovláken. Praktická časť sa koncentruje sa prípravu mikrovláken zo spomínaného poly(3-hydroxybutyrátu). Sledované a optimalizované sú viaceré parametre vedúce k lepšej zvlákniteľnosti materiálu. Praktická časť je rozšírená o modifikáciu polymérneho roztoku prídavkom iných biopolymérov a zmäkčovadiel a prípravu mikrovláken z takto modifikovanej polymérnej zmesi. Pozornosť je venovaná taktiež optimalizácii procesných parametrov. Pripravené mikrovlákna sú následne analyzované a charakterizované viacerými metódami a vzájomne porovnávané s cieľom vyvinúť alternatívu k súčasne používaným substrátom pre rast buniek v 3D.
7

Polyhydroxyalkanoates production by a bacterium isolated from mangrove soil samples collected from Quang Ninh province / Vi khuẩn sinh tổng hợp polyhydroxyalkanoates phân lập từ đất rừng ngập mặn tỉnh Quảng Ninh

Doan, Thuoc Van, Nguyen, Binh Thi 15 July 2013 (has links) (PDF)
A PHA producing bacterium (strain QN271) was selected from mangrove soil samples collected from Quang Ninh province by using the Nile red dying technique. PHA accumulation in the selected bacterium strain was confirmed by transmission electron microscope. With the exception of maltose or sucrose, the bacterium strain was found to be able to synthesize PHA from various carbon sources (glucose, xylose, fructose, glycerol, and glucose plus propionate). The strain accumulated poly(3-hydroxybutyrate) from glucose, fructose, xylose, and glycerol whereas poly(3-hydroxybutyrate-co-3-hydroxyvalarate) was produced when a combination of glucose and propionate was included in the culture medium. Fructose was found to be most suitable substrate for PHA synthesis by strain QN271. PHA content of 63.3% and CDW of 6 g/L were obtained after 32 hrs of cultivation in fructose medium. / Chủng vi khuẩn có khả năng sinh tổng hợp PHA đã được phân lập từ đất rừng ngập mặn tỉnh Quảng Ninh nhờ kỹ thuật nhuộm với Nile red. Ảnh quan sát dưới kính hiển vi điện tử dẫn truyền chứng tỏ rằng chủng vi khuẩn này có khả năng tích lũy lượng lớn PHA trong tế bào. Chủng vi khuẩn tuyển chọn có khả năng sinh tổng hợp PHA từ nhiều nguồn các bon khác nhau như glucose, xylose, fructose, glucerol, glucose và propionate nhưng không có khả năng tổng hợp PHA từ maltose hoặc saccharose. Chủng vi khuẩn tuyển chọn tổng hợp poly (3-hydroxybutyrate) từ các nguồn các-bon như glucose, xylose, fructose, hay glycerol, trong khi đó poly (3-hydroxybutyrateco- 3-hydroxyvalarate) sẽ được tổng hợp khi phối hợp sử dụng hai nguồn các-bon (glucose và propionate). Fructose là nguồn các-bon tốt nhất cho chủng QN271 sinh tổng hợp PHA, khi nuôi cấy trong môi trường có fructose chủng vi khuẩn này có thể tạo ra lượng sinh khối là 6 g/L trong đó có chứa 63.3% PHA sau 32 giờ.
8

The Crystallization of Side Chain Effect on the Performances of Poly(3-dodecylthiophene)/fullerene ¡§Bulk Heterojunction¡¨ Solar Cells

Wang, Shin-guo 21 July 2009 (has links)
P3DDT (3-dodecylthiophene-2,5-diyl) and PCBM( [6,6]-phenyl C61-butyric acid methyl ester) were fabricated to the active layer of Bulk Heterojunction Organic Solar Cells .We obtained the device efficiency was 0.64 % by evaporating solvent at room temperature. We measured Thermal decomposition Temperature (Td) of P3DDT was 487¢J. But operational temperature was over 90¢J, it could affect the roughness of thin film and make efficiency to be 4¡Ñ10-3(%). For results of experiments, we know that roughness changed by the crystallization of side chain and exciton dissociation modified by the morphology between P3DDT and PCBM. Thin film solar cell has a large effect on the formation of active layer, such as heat treatment, choices of solvents, composition ratio, and speed of spin coating. The efficiency of solar cell has been shown to be highly sensitive to the size, composition and crystallization of the formed domains. We studied two kinds of conjugated polythiophenes with the same main chain but different side chain. When the number of carbon atoms of alkyl side chains is more than 10, some orderly arrangements will occur for side chains between the layers. We tried to explain the crystallization caused by long alkyl side chains determined which intrinsic phenomena are the most evident for altering the PCE of solar cell. After recrystallization, the layered structures of P3DDT can be improved, but those orderly degrees of the arrangements with PCBM are further aggregated. The main point for low PEC and Jsc by heat treatment is the unfavorable and roughened morphology. Charge transfer only occurs at the boundary ,which is interfacial area between donor and acceptor materials, hence, the low Jsc could be caused by poor charge transfer between P3DDT and PCBM. The redistributed arrangement of P3DDT domains exclude PCBM from original space, and it makes PCBM to aggregate large particles, from nanophase to mesophase scales, which reduce mutual solubility to be the source of PCE and Jsc reduction.
9

PRODUCTION OF MEDIUM-CHAIN-LENGTH POLY(3-HYDROXYALKANOATES) USING PSEUDOMONAS CITRONELLOLIS DSM50332 AND P. PUTIDA KT2440 IN CONTINUOUS REACTOR SYSTEMS

GILLIS, JAMES 20 December 2011 (has links)
In vivo production of medium-chain-length poly(3-hydroxyalkanoates) (MCL-PHA) containing a side chain carboxyl group from azelaic acid (AzA), a nine-carbon α,ω-dicarboxylic acid, was investigated using Pseudomonas citronellolis DSM 50332 in a phosphate (P)-limited chemostat. Co-feeding with nonanoic acid (NA) and inhibition of β-oxidation with acrylic acid (AA) were strategies that were used to stimulate the incorporation of carboxylated monomers, but both were unsuccessful. P. citronellolis DSM50332 was capable of growing on AzA as a sole source of carbon and energy, indicating that enzymes in β-oxidation utilized AzA and its derivatives. However, the MCL-PHA produced from AzA comprised 3-hydroxyoctanoate (C8) and 3-hydroxydecanoate (C10) monomers, which was consistent with precursor supplied via the de novo fatty acid biosynthesis pathway. This evidence suggests that one or more of 3-ketoacyl-CoA reductase (FabG), enoyl-CoA hydratase (PhaJ) and PHA synthase (PhaC) of this organism do not have the low specificity required to utilize a carboxylated substrate. Future work involving mutations may broaden the substrate specificity of these key enzymes to overcome this obstacle. Two-stage high-cell density carbon (C)-limited chemostat cultivation of P. putida KT2440 was examined for MCL-PHA production from nonanoic acid (NA) at high intracellular polymer content and volumetric productivity. Growth conditions stimulating good PHA production were first established in single-stage chemostat, which yielded 63.1 wt% PHA containing 90 mol% C9 units and a productivity of 1.52 g L-1h-1 at a dilution rate of 0.30 h-1. This productivity was higher than any value reported in literature for continuous MCL-PHA production systems and comparable to the upper range of fed-batch results. Two-stage production yielded promising results, notably the increase in polymer content from the first to second stage. However, complications involving foaming and an unexplained decline in PHA content adversely affected system performance. The best PHA content and overall productivity were 58.5 wt% and 0.76 g L-1h-1, respectively. Nonetheless, the results demonstrate the potential to achieve high PHA content without the need for pure oxygen at high dilution rates, warranting further investigation focusing on the optimization of growth conditions. / Thesis (Master, Chemical Engineering) -- Queen's University, 2011-12-19 15:48:21.808
10

Blendas com poli(3-hidroxibutirato) (PHB) e copolimeros aleatorios = comportamento de fases e cinetica de cristalização / Blends of poly(3-hydroxybutyrate) and random copolymers : phase behavior and crystallization kinetics

Taba, Eduardo dos Santos 15 August 2018 (has links)
Orientador: Maria Isabel Felisberti / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Quimica / Made available in DSpace on 2018-08-15T06:00:08Z (GMT). No. of bitstreams: 1 Taba_EduardodosSantos_D.pdf: 4256071 bytes, checksum: ec0a3acba638d80495c8dfba90548e34 (MD5) Previous issue date: 2009 / Resumo: Blendas do polímero biodegradável poli(hidroxibutirato) foram preparadas com os seguintes copolímeros aleatórios: poli(estireno-co-acrilonitrila)-SAN; poli(estireno-co-metacrilato de 2-hidróxietila)-S-Hema; poli(metacrilato de metila-co-vinil fenol-P(MMA-co-VPh). Os copolímeros SAN foram sintetizados via copolimerização em massa, enquanto os copolímeros S-Hema foram sintetizados pela copolimerização em solução utilizando DMF como solvente. Os copolímeros foram caracterizados por ressonância magnética nuclear (RMN) de H e C, cromatografia de permeação em gel (GPC), calorimetria exploratória diferencial (DSC) e análise dinâmico-mecânica (DMA). As blendas foram preparadas dissolvendo-se os polímeros em um bom solvente e adicionando-se à solução resultante um mau solvente para a coagulação dessas blendas. As análises das blendas por DSC, DMA e microscopia eletrônica de varredura (SEM) mostraram que todas elas são imiscíveis. A cinética de cristalização do PHB em blendas P(MMA-co-VPh)/PHB e SAN/PHB foi estudada por DSC. Esses estudos mostraram que a presença do copolímero P(MMA-co-VPh) causa a diminuição da taxa de cristalização do PHB e aumenta a energia de ativação do processo de cristalização do PHB. Para as blendas PHB/SAN, o efeito do copolímero em diminuir a taxa de cristalização do PHB é menor que nas blendas PHB/P(MMAco- VPh). Além disso, o teor de acrilonitrila no copolímero pouco afeta a taxa de cristalização do PHB. Os expoentes de Avrami ¿n¿ determinados para a cristalização do PHB nas blendas P(MMA-co-VPh)/PHB e SAN/PHB são aproximadamente iguais ao expoente ¿n¿ para o PHB puro indicando que o mecanismo de cristalização do PHB não se altera nas blendas. Sendo assim, este trabalho possibilitou o entendimento de aspectos importantes referentes ao comportamento de fases e à cinética de cristalização de blendas contendo PHB associado a copolímeros aleatórios.Os estudos cinéticos podem colaborar para a compreensão do comportamento de cristalização de copolímeros/PHB em equipamentos de processamento. Além disso, esse estudo pode ajudar na escolha do copolímero e de sua composição para um melhor controle da cristalização do PHB nessas blendas / Abstract: Blends of biodegradable poly(hydroxybutyrate) were prepared with the following random copolymers: poly(styrene-co-acrylonitrile)-SAN; poly(styrene-co-2-hydroxyethylmethacrilate)-S-Hema; poly(methylmethacrylateco- vinylphenol)-P(MMA-co-VPh).SAN copolymers were synthesized by bulk copolymerization; while S-Hema copolymers were synthesized by solution copolymerization using DMF as solvent. The resulting copolymers were characterized by nuclear magnetic resonance (RMN) of H and C, gel permeation chromatography (GPC), differential scanning calorimetry (DSC) and dynamic-mechanical analysis (DMA). Blends were prepared using coprecipitation method where a binary homogeneous soilution was added to a large volume of non solvent. DSC, DMA and scanning electron microscopy (SEM) analysis revealed that all the blends are immiscible in the entire composition range. Despite the immiscible blends, DSC analysis show that the copolymers interferes in the PHB crystallization, being capable of suppress this process in some blends. Crystallization kinetics of the PHB in PHB/P(MMA-co-VPh) and PHB/SAN blends was studied by DSC and the results revealed that the presence of P(MMA-co-VPh) copolymer decreases the PHB crystallization rate and increases the activation energy for the overall crystallization process. In respect to PHB/SAN blends, the influence of the copolymer in decrease the PHB crystallization rate is lower than the observed in PHB/P(MMA-co-VPh) blends. Moreover, the acrylonitrile concentration in the copolymer causes little effect in the PHB crystallization rate. The Avrami exponent ¿n¿ determined for the crystallization process in PHB/P(MMA-co-VPh) and SAN/PHB blends are approximately equal to the ¿n¿ exponent for pure PHB indicating that the crystallization mechanisms for pure PHB do not change in the blends. This work made possible the understanding of important aspects of the phase behavior and crystallization kinetics of random copolymers/PHB blends. The crystallization kinetics studies can collaborate for the understanding of the behavior of crystallization of these blends in processing equipments. Moreover, this study can help in the choice of the copolymer and its composition for better control of the crystallization of PHB in these blends / Doutorado / Físico-Química / Doutor em Ciências

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