Dissertations / Theses on the topic 'HOMO POLYMER'

Membrane gas separation emerged as a commercial process on a large scale during the 1980s. When compared to other gas separation processes such as cryogenics, adsorption and absorption, membrane separation competes primarily on the basis of overall economics and convenience, but not on the basis of product purity. For example, membranes have been used for offshore natural gas processing because they reduce the size and the weight of the processing units, require less maintenance and less operator supervision. In order to improve product purity, development of new membrane materials, and modification of existing membrane material for better gas separation properties, is required. This research focused on preparation and characterization of new copolymers from the family of polyphenylene oxides. This family of polymers was chosen because of the properties of its best-known representative, poly(2,6-dimethyl-1,4-phenylene oxide), which shows one of the highest rates of permeability for gases among glassy polymers, exhibits excellent film-forming properties, and is resistant to a number of chemical agents. The study was divided into two parts: (1) homopolymers and both block and random copolymers of different composition were synthesized by oxidative coupling of 2,6-diphenylphenol and 2,6-dimethylphenol; (2) the physical and gas transport properties of the polymers were determined. (Abstract shortened by UMI.)

Recent experimental studies indicate that polymeric structures with a well-adjusted balance of amphiphilic parts may translocate through self-assembled phospholipid bilayers and enhance the passive trans-membrane transport of smaller molecules. Using a coarse grained lattice Monte Carlo model with explicit solvent we investigate self-assembled lipid bilayers interacting with a linear polymer chain under variation of the hydrophobicity of the chain. Here, we focus on the relationship between the chain's hydrophobicity and its translocation behavior through the membrane as well as induced membrane perturbations. We show, that there is an adsorption transition of the polymer at the bilayer interface, where effectively the solvent phase and the tail phase of the bilayer are equally repulsive for the polymer. Close to this adsorption threshold of the polymer both the translocation probability of the polymer as well as the permeability of the membrane with respect to solvent are enhanced significantly. The frequency of polymer translocation events can be understood quantitatively assuming a simple diffusion along a one-dimensional free energy profile, which is controlled by the effective lipophilicity of the chain and the tail-packing in the bilayer's core
Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich

Recent experimental studies indicate that polymeric structures with a well-adjusted balance of amphiphilic parts may translocate through self-assembled phospholipid bilayers and enhance the passive trans-membrane transport of smaller molecules. Using a coarse grained lattice Monte Carlo model with explicit solvent we investigate self-assembled lipid bilayers interacting with a linear polymer chain under variation of the hydrophobicity of the chain. Here, we focus on the relationship between the chain's hydrophobicity and its translocation behavior through the membrane as well as induced membrane perturbations. We show, that there is an adsorption transition of the polymer at the bilayer interface, where effectively the solvent phase and the tail phase of the bilayer are equally repulsive for the polymer. Close to this adsorption threshold of the polymer both the translocation probability of the polymer as well as the permeability of the membrane with respect to solvent are enhanced significantly. The frequency of polymer translocation events can be understood quantitatively assuming a simple diffusion along a one-dimensional free energy profile, which is controlled by the effective lipophilicity of the chain and the tail-packing in the bilayer's core.
Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.

In the present work the functionalisation of oligomers of butadiene (liquid 1,2-polybutadiene PBL) and of oligomers of a random copolymer butadiene/styrene (SBRL) was performed by the addition of either N-acetyl-L-cysteine, N-acetyl-L-cysteine methyl ester or L-cysteine methyl ester through the thiol-ene radical reaction. Functionalisation was carried out in solution and in presence of a free radical initiator (2,2’-azobisisobutyronitrile, AIBN). The initial feed ratio polymer / cysteine derivative / initiator was varied, in order to highlight the occurrence of side reactions and to understand their possible influence on the reaction mechanism. The 1H-NMR determination of the functionalisation extent brought out that the addition degrees of thiols were always high, regardless of the initial initial thiol / double bond ratio; the complete conversion of the double bonds, however, was never reached because of side-reactions. In order to better understand the occurrence of the latters, reactions with AIBN or with other free radical generating species were performed, in absence of thiol; the purpose of these experiments was to reproduce the presence of macroradicals similar to those generated during the thiol addition, and to investigate their reactivity towards other macromolecules present in the reaction environment. The reaction products of these runs were characterised, and some conclusions were drawn regarding the different type of side reactions occurring with the two polymeric substrates (PBL or SBRL). The high functionalisation degrees often caused a drastic change in the macroscopic properties of the polymers, ranging from improved solubility in hydrophilic solvents (for instance in alkaline aqueous solutions) to a remarkable increase of the glass transition temperature. Chiral properties were carried from the functionalising agents to the modified polymers; this phenomenon was evaluated by polarimetry of polymer solutions in organic solvents, and discussed with reference to the reciprocal proximity of the L-cysteine side chains. Circular dichroism measurements were also performed in order to investigate the possible presence of secondary / tertiary structures analogously to what reported in scientific literature for similar systems. In the last part of this work, a possible use of (N-acetyl-L-cysteine)-functionalised products was evaluated; the hydrophilically-modified polymers showed the ability to act as coupling agents between hydrophobic polymeric matrices and inorganic, hydrophilic fillers in composite materials. The incorporation of the functionalised polymers (PBL and SBRL having various functionalisation degrees) in compounds for ground tyres was performed, and the rheological / mechanical properties of the resulting compounds were evaluated; the formulation used are highly innovative compounds including an elevated silica content.

Graft copolymers constitute an important class of copolymers since it is possible to tune their characteristics opportunely designing their macromolecular structure. There is a growing interest for the design and synthesis of graft copolymers with desired composition and functionality to be used in a wide range of applications. Free radical polymerization techniques offer the straightforward synthesis of amphiphilic graft copolymers materials thanks also to the vast choice of available monomers with different functional groups. Amphiphilic graft copolymers, or polymer containing both hydrophilic and hydrophobic parts in their structure, possess unique properties due to the distinct chemical nature of building blocks and can self-assembly to various morphologies to render the favorable interactions. Characteristics of graft copolymers can be adjusted through the variations of composition (type of the grafted chains, grafting densities) and architecture (length of backbone and grafted chains etc.). Therefore, understanding the relation between the macromolecular architecture, composition and characteristics is crucial to tailor polymers for specific applications. This thesis covers the synthesis, characterization, and applications of amphiphilic graft copolymers, to reveal the effects of their chemical structure on capsules formation, encapsulation of fragrance molecules, and biodegradability rate. A wide range of applications can be defined for the use of amphiphilic copolymers. This work focuses on the self-assembly properties of amphiphilic copolymers, with improved environmental profile, for potential use in perfume sustainable encapsulation technology in liquid home- and personal-care products. To achieve the synthesis of copolymers with self-assembled structures, hydrophilic poly (ethylene glycols) (PEGs) of different molecular weights, hydrophilic and hydrophobic monomers like thermo-responsive N-vinyl caprolactam (VCL) and/or vinyl acetate (VAc), have been used. Amphiphilic copolymers were obtained through a radical polymerization method using peroxide as an initiator. Different molecular weights (lengths of the chain), grafting densities as well as various chemical moieties have been investigated. Synthetized materials were characterized by FT-IR, 1D NMR, 2D NMR, DSC, TGA, GPC, ToF-Sims. Biodegradability of copolymers was measured by OECD 301b test and capsules formation properties were investigated using fluorescence microscopy. The studies reported in this work demonstrated that the capsules formation by synthetized copolymers in liquid detergent formulations strongly depend on the molecular weight of hydrophobic content and the degree of grafting of hydrophobic graft chains. Among all synthetized copolymers and commercial copolymer Soluplus only copolymer S2, which has the highest molecular weight of hydrophobic PVAc-co-PVCL part and higher grafting degree, showed capsules formation and encapsulation of perfume and PRMs in both SLFE liquid detergent formulations and water matrix. All synthesized copolymers are 4 -5 folds more biodegradable than commercial Soluplus.

The rapid development in perovskite solar cells (PSC) has generated a tremendous interest in the photovoltaic community. The power conversion efficiency (PCE) of these devices has increased from 3.8% in 2009 to a recent certified efficiency of over 20% which is mainly the product of the remarkable properties of the perovskite absorber material. One of the most important advances occurred with the replacement of the liquid electrolyte with a solid state hole conductor which enhanced PCE values and improved the device stability. Spiro-OMeTAD (2,2',7,7'-tetrakis(N,N'-di-p-methoxyphenylamine)- 9,9'-spirobifluorene) is the most common hole transport material in perovskite solar cells. Nevertheless, the poor conductivity, low charge transport and expensive synthetic procedure and purification have limited its commercialisation. Triphenylamines (TPA) like Spiro-OMeTAD are commonly employed due to the easy oxidation of the nitrogen centre and good charge transport. Other triarylamines have similar properties to Spiro-OMeTAD but are easier to synthesise. The aim of this doctoral thesis is to investigate different types of hole transport materials in perovskite solar cells. Three different series of triphenylamine-based HTM were designed, synthesised, characterised and studied their function in perovskite solar cells. A series of five diacetylide-triphenylamine (DATPA) derivatives (Chapter 3) with different alkyl chain length in the para position was successfully synthesised through a five step synthesis procedure. A range of characterisation techniques was carried out on the molecules including; optical, electrochemical, thermal and computational methods. The results show that the new HTMs have desirable optical and electrochemical properties, with absorption in the UV, a reversible redox property and a suitable highest occupied molecular orbital (HOMO) energy level for hole transport. Perovskite solar cell device performances were studied and discussed in detail. This project studied the effect of varying the alkyl chain length on structurally similar triarylamine-based hole transport materials on their thermal, optical, electrochemical and charge transport properties as well as their molecular packing and solar cell parameters, thus providing insightful information on the design of hole transport materials in the future. The methoxy derivative showed the best semiconductive properties with the highest charge mobility, better interfacial charge transfer properties and highest PCE value (5.63%). The use of p-type semiconducting polymers are advantageous over small molecules because of their simple deposition, low cost and reproducibility. Styrenic triarylamines (Chapter 4) were prepared by the Hartwig-Buchwald coupling followed by their radical polymerization. All monomers and polymers were fully characterised through electrochemical, spectroscopic and computational techniques showing suitable HOMO energy levels and desirable optoelectrochemical properties. The properties and performance of these monomers and polymers as HTMs in perovskite solar cells were compared in terms of their structure. Despite the lower efficiencies, the polymers showed superior reproducibility on each of the device parameters in comparison with the monomers and spiro-OMeTAD. Finally, star-shaped structures combine the advantages of both small molecules, like well-defined structures and physical properties, and polymers such as good thermal stability. Two star-shaped triarylamine-based molecules (Chapter 5) were synthesised, fully characterised and their function as hole-transport materials in perovskite solar cells studied. These materials afford a PCE of 13.63% and high reproducibility and device stability. In total this work provided three series of triarylamine-based hole transport materials for perovskite solar cells application and enabled a comparison of the pros and cons of different design structures: small-molecule, polymeric and star-shaped.

Polypropylene is one of the most important polymers being used today. The applications of polypropylene range from household appliances to packaging and the greatest use of it is in automobiles. To enhance its properties, fillers are added to it such as talc, calcium carbonate, etc. An attempt has been made in this regard to replace commercial calcium carbonate filler by egg shells. Egg shells constitute about 95 percent of calcium carbonate and its disposal constitutes a serious environmental hazard. Varying compositions of polypropylene (PP) composites were prepared and the results were compared with commercial calcium carbonate reinforced PP. The results indicated a substantial improvement in the Young’s modulus (E) with the increment of egg shell content, moreover impact strength was also found to increase. A further improvement in the properties was observed by surface modification of egg shells with isophthalic acid. Scanning electron microscopy images revealed an improvement in the interfacial bonding the surface modified egg shell powder as compared to the unmodified egg shell powder and calcium carbonate. The results indicate the potential of egg shells to be used as filler for polypropylene replacing the commercial calcium carbonate.

碩士
國立清華大學
化學工程學系
104
Abstract Colloidal Quantum dots have unique characteristics, such as high photoluminescence quantum efficiency, pure color emission, solution process, large area production and are potential candidate to replace OLED and PLED. Recently, CdSe/ZnS-based quantum dots device demonstrates high current efficiency, high brightness and long operating life time. In this work, gradient core-shell CdSe/ZnS is coated with additional ZnS shell for longer exciton life time (CdSe@ZnS/ZnS). It is found that insulating oleophilic ligands oleic acid (OA) and trioctylphosphine (TOP) are both on QDs film/surface as examined by X-ray photoelectron spectroscopy (XPS). With high temperature annealing process, the loss of partial ligands lead to enhanced electron injection, improved PL intensity and resistivity to organic solvent. In general, the alignment between QDs layer and hole transport layer have large hole injection barrier (>1 eV), resulting in unbalanced charge injection. To solve this high injection barrier problem, we design molecular-scale graded HOMO levels polymer for improved hole injection, which allows hole carriers to inject to QDs layer via four consecutive steps by grafting triphenylamine (TPA), carbazole (Cz) and 1,3-Bis(N-carbazolyl)benzene (mCP) hole transport moieties on the side chains of spiro-polyfluorene. The inverted-type structure ITO/ZnO/(CdSe@ZnS/ZnS)/gradient spiro-polyfluorene/MoO3/Al have the brightest luminance over 200,000 cd/m2 and the highest current efficiency 36.1 cd/A, among the reported results of inverted-type QD-LED. Furthermore, the first all solution-processable invert type structure is fabricated also by replacing vacuum-deposited MoO3 with solution-processed MoO3. It gives the performance with the maximum brightness 239,500 cd/m2 and efficiency 22.4 cd/A.

碩士
國立交通大學
材料科學與工程學系
100
In this study, the novel dissoluble homo-/co-polymers was synthesized with chemical modification. The chemical structure of this amphiphilic copolymer was characterized by FT-IR, 1H-nuclear magnetic resonance and 13C-, 29Si-solid state nuclear magnetic resonance. In addition, the characteristics of amphiphilic copolymer are dissoluble, easy fabrication, high hydrophobicity, oxygen permeability, and can load hydrophobic drug into the hydrogel, forming by chemical crosslink. Due to the interaction of hydrophilic-hydrophobic portions of amphiphilic copolymer with the surrounding environment, the structural morphology of the amphiphilic copolymer was investigated using scanning electron microscopy (SEM), transmission electron microscopy (TEM) . And the mean sizes of homo-/co-polymers were characterized by dynamic light scatter (DLS). For heat and/or light sensitive hydrophobic drugs, the novel dissoluble homo-/co-polymers prevent interaction of the drugs from heat/photopolymerization. A subsequent application to carry vitamin A as model drug into homo-polymers hydrogels compared with the traditional hydrogel. The experimental results indicated a long-term release for drug in homo-polymers hydrogels than the traditional hydrogel. Finally, the homo- and co-polymers showed outstanding biocompatibilities toward the BCE cell line and Hs68 cell line, where the homo-/co-polymers coating on the lenses against the BCE cell line and the homo-/co-polymers based hydrogels against Hs68 cell line, respectively. These results suggest a promising vehicle for medical application.

Die Zustandsbewertung von Kabeln mit vernetzter Polyethylen-Isolierung (VPE) ist seit vielen Jahren eine große Herausforderung, da die Alterungsmechanismen nicht vollständig geklärt sind. Die Zuverlässigkeit der Ergebnisse von Verfahren zur Bewertung des integralen Zustandes der VPE-isolierten Mittelspannungskabel wird kontrovers diskutiert oder teilweise in Frage gestellt. Bei Kenntnis des Alterungsverhaltens und der wirkenden Einflussfaktoren kann Verlustfaktor tan δ der VPE-Mittelspannungskabel wichtige Hinweise auf den Zustand geben. Bei der Bewertung des Zustandes auf Basis des Verlustfaktors tan δ müssen die in der VPE-Hauptisolierung befindlichen Zuschlagstoffe berücksichtigt werden. In Abhängigkeit der Zugaben von Homo- oder Co-Polymeren ist ein grundsätzlich unterschiedliches Alterungsverhalten möglich, das zu Fehlinterpretation führen kann. Die messtechnisch gewonnenen Aussagen wurden über ein Dreischicht-Modell bestätigt, mit dem das elektrische Verhalten der Kabelisolierung verifiziert werden konnte. In der Arbeit werden wesentliche Schlussfolgerungen zur Auswirkung thermischer Beanspruchungen über der Einsatzdauer formuliert. Es wird ein Verfahren vorgestellt, mit dem es perspektivisch möglich sein kann, den Zustand eines VPE-Kabels abzuschätzen. Das Verfahren reduziert den Einfluss der messspezifischen Faktoren.:Inhaltsverzeichnis i Abkürzungsverzeichnis i Symbolverzeichnis iii Kurzfassung v Danksagung vi 1 Einleitung 1 1.1 Motivation 1 1.2 Bisherige Anwendungen der Verlustfaktormessungen an VPE-Kabeln 3 1.3 Zielsetzung der Arbeit 6 1.4 Struktur der Arbeit 8 2 Eigenschaften von VPE-Kabeln 11 2.1 Aufbau der VPE-Kabel 11 2.2 Entwicklung der Kunststoff-Kabeltechnologie 12 2.3 Struktur und Morphologie von PE/VPE-Isolierungen 15 2.4 Zusammensetzung und Eigenschaften der halbleitenden Schichten 18 2.5 Alterungsmechanismen bei VPE-Kabeln 19 3 Dielektrische Eigenschaften von VPE-Kabeln 23 3.1 Dielektrischer Verlustfaktor 23 3.2 Polarisationsmechanismen der PE/VPE-Isolierung 23 3.3 Leitungsmechanismen im Polyethylen 25 3.4 Ersatzanordnungen zur Nachbildung des Verlustfaktors 28 3.5 Dreischicht-Modell zur Nachbildung des Verlustfaktors 35 3.5.1 Aufbau des Simulations-Dreischicht-Modells 43 3.5.2 Materialparameter der drei Kabelhauptschichten 45 4 Verlustfaktormessungen an VPE-Kabeln 49 4.1 Messeinrichtungen zur Verlustfaktormessung 49 4.1.1 Frequenzbereichsspektroskopie (FDS-Messung) 49 4.1.2 Vektorielle Impedanzmessung (VI-Messung) 50 4.2 Umfang der Prüfobjekte 51 4.3 Konfektionierung der VPE-Kabel 53 4.4 Aufnahme einer Verlustfaktor-Referenzkurve 56 4.5 Störeinflüsse auf die Messung des Verlustfaktors 56 4.5.1 Äußere Einflüsse 57 4.5.2 Innere Einflüsse 58 4.6 Versuchsvorbereitung und -durchführung 62 4.6.1 Einfluss der Temperaturabhängigkeit auf den Verlustfaktor 62 4.6.2 Einfluss der thermischen Beanspruchung auf den Verlustfaktor 62 4.6.3 Einfluss der Einwirkung von Wasser auf den Verlustfaktor 63 5 Auswertung und Diskussion der Messergebnisse 66 5.1 Frequenzabhängigkeit des Verlustfaktors 66 5.1.1 Neuwertige VPE-Kabel 66 5.1.2 Betriebsgealterte VPE-Kabel 73 5.2 Spannungsabhängigkeit des Verlustfaktors 76 5.2.1 Spannungsabhängigkeit im Frequenzbereich 40 – 280 Hz 76 5.2.2 Spannungsabhängigkeit bei einer Frequenz von 0,1 Hz 79 5.3 Einflussfaktoren auf den frequenzabhängigen Verlustfaktor 81 5.3.1 Temperaturabhängigkeit des Verlustfaktors 81 5.3.2 Abhängigkeit des Verlustfaktors von der thermischen Beanspruchung 90 5.3.3 Abhängigkeit des Verlustfaktors von der Wasserlagerung 94 6 Zusammenfassung und Ausblick 97 Anhang 103 Abbildungsverzeichnis 105 Tabellenverzeichnis 109 Literaturverzeichnis 110 Thesen 129