Dissertations / Theses on the topic 'Poly(2-vinylpyridine)'

Emulsion polymerisation of 2-vinylpyridine (2VP) in the presence of divinylbenzene (DVB) cross-linker, a cationic surfactant and monomethoxy-capped poly(ethylene glycol) methacrylate (PEGMA) macromonomer, at around neutral pH and 60°C afforded near-monodisperse, sterically-stabilised latexes at approximately 10 % solids. Judicious selection of the synthesis parameters enabled the mean latex diameter to be varied from 370 to 970 nm depending on the initiator, polymeric stabiliser and surfactant concentrations. These lightly cross-linked latexes acquired cationic microgel character at low pH, as expected. The critical pH for this latex-to-microgel transition was around pH 4.1 at 1.0 wt. % DVB. The kinetics of swelling of these near-monodisperse, lightly cross-linked poly(2vinylpyridine) [PEGMA-P2VP] latexes was investigated by the pH jump method using a commercial stopped-flow instrument. The characteristic swelling time (tens of milliseconds) correlates linearly with the mean particle diameter, as predicted by the Tanaka equation. However, faster swelling was observed in the presence of added salt. This salt effect was not expected from Tanaka theory. Kinetics of deswelling for the PEGMA-P2VP microgel-to-Iatex transition was also investigated. Slower deswelling time scales of the order of hundreds of seconds were observed due to retarded salt excretion from the microgel. A near-monodisperse styrene-functionalised poly[2-(dimethylamino)ethyl methacrylate] [PDMA] macromonomer was evaluated as a reactive steric stabiliser for the preparation of P2VP latexes via emulsion polymerisation. The solution pH was shown to be a critical parameter for successful syntheses: stable latexes with minimal coagulum were only obtained at (or above) neutral pH. Combined DLS and electrophoretic data indicated that the PDMA-P2VP particles existed in three states depending on the solution pH: swollen microgels were obtained at low pH, non-solvated latex particles with a cationic stabiliser layer were obtained at intermediate pH and flocculated latex particles with neutral PDMA stabiliser chains were obtained at around pH 8.5. A PDMA-P2VP latex of 280 nm was shown to be an efficient pH-responsive Pickering emulsifier for stabilising water-in-1undecanol emulsions. Three near-monodisperse heavily cross-linked PEGMA-P2VP latexes of 380 nm, 640 nm and 820 nm diameter were prepared in tum by emulsion copolymerisation of 2VP and DVB (5.0 wt.%) using PEGMA macromonomer. Each of these latexes proved to be an effective particulate stabiliser for the production of long-lived foams generated by either hand-shaking or using foam columns. Dried foams prepared using the 380 nm latex exhibited interesting optical effects when viewed in reflectance mode. These PEGMAP2VP latex foams can be readily destabilised at low pH due to the latex-to-microgel transition. Finally, solution viscosities of PEGMA-P2VP microgels prepared with lower levels of DVB cross-linker were measured at low pH. Free-standing gels were obtained for aqueous solutions of PEGMA-P2VP particles prepared with 0.16 wt.% of DVB crosslinker at 1.0 w/v % and pH 3.4. However, no gels could be formed in the presence of added salt, even at salt concentrations as low as 0.01 M NaC!. Copolymerisation of 2VP with either methyl acrylate or ethyl acrylate did not alleviate this salt sensitivity.

Although, the use of vinyl pyridine polymers, especially as matrices for nanoparticle synthesis, is growing considerably, the knowledge of thermal degradation behavior is still missing in the literature. In this study, thermal degradation characteristics of the homopolymers
poly(4-vinylpyridine), P4VP, and poly(2-vinylpyridine), P2VP, the diblock copolymers
polystyrene-blockpoly( 2-vinylpyridine), (PS-b-P2VP) and polystyrene-block-poly(4-vinylpyridine), (PS-b-P4VP), and the metal functional vinyl polymers
cobalt-polystyrene-blockpoly( 2-vinylpyridine) and cobalt-polystyrene-block-poly(4-vinylpyridine) were investigated by direct pyrolysis mass spectrometry. The effects of the position of the nitrogen in the pyridine ring, composition and molecular weight of diblock copolymer and coordination of the metal to the pyridine ring of the copolymer on thermal behavior were also investigated. The results showed that unlike most of the vinyl polymers that decompose via depolymerization, P2VP degrades through opposing reaction pathways
depolymerization, proton transfer to N atom in the pyridine ring yielding unsaturated linkages on the polymer backbone that decompose slightly at higher temperatures and loss of pyridine units. On the other hand the thermally less stable P4VP decomposition follows v depolymerization in accordance to general expectations. Another finding was the independent decomposition of both components of the diblock polymers, (PS-b- P2VP) and (PS-b-P4VP). Thermal degradation occurs in two main steps, the thermally less stable P2VP or P4VP chains degrade in the first step and in the second step decomposition of PS takes place. It was also concluded that upon coordination of metal, thermal stability of both P2VP and P4VP increases significantly. For metal functional diblock copolymers thermal degradation of chains coordinated to Co metal through N in the pyridine ring occurred in three steps
cleavage of pyridine coordinated to Co, coupling and H-transfer reactions yielding unsaturated and/or crosslinked structure and decomposition of these thermally more stable unsaturated and/or crosslinked blocks. TEM imaging of the metal functional block copolymers along with the results of the pyrolysis mass spectrometry pointed out that PS-b-P2VP polymer is a better and more effective matrix for nanoparticle synthesis.

Dans cette thèse, nous nous sommes attachés à préparer des films minces nanostructurés à partir de copolymères à blocs et de les caractériser par différentes techniques (AFM, MET et GISAXS). Le but de la recherche est de réaliser des nanostructurations originales en films minces afin de prendre en compte l'effet de confinement (quantité de matière limitée, interaction avec la surface ...) et de comprendre les phénomènes se produisant au cours de la structuration. Les travaux ont porté sur la mise en œuvre des films minces, leur réorganisation sous vapeur de solvant et leur caractérisation.Plus spécifiquement, les travaux de thèse ont porté sur l’étude de copolymères triblocs linéaires ISP (PI-b-PS-b-P2VP) (seuls ou en mélanges) en films minces, déjà étudié en volume par un laboratoire partenaire de l’Université de Nagoya. Nous avons développé des méthodes de caractérisation adaptées à ce polymère en film mince, en particulier une technique originale de GISAXS reposant sur le marquage sélectif des blocs par des éléments lourds (iode, osmium). Ceci nous a permis de confirmer la structure interne et la forme de l’interface (rayon de courbure) des domaines minoritaires, d’observer des transitions structurales originales. La présence de couches de mouillage aux deux interfaces du film (film/air et film/substrat) est une caractéristique commune à tous les systèmes.Tout d’abord, des triblocs seuls, se trouvant à la limite des différentes morphologies sur le diagramme de phase, ont été étudiés en film mince. Contrairement à ce qui a été observé en volume, des transitions structurales (CYL-SPH et GYD-CYL) ont été observées. Notamment, la transition d’une structure gyroïde alternée présentant une symétrie Q214 vers des cylindres avec une symétrie P2mm (pas d’arrangement typique hexagonal) représente, pour des terpolymères triblocs, un des résultats majeurs de la thèse. Le mécanisme de transition structurale a été élucidé par différentes techniques de caractérisation montrant une relation d’épitaxie entre les deux phases. Ensuite, nous nous sommes focalisés sur la nanostructuration de mélanges de triblocs. Nous avons montré la possibilité d’obtenir des domaines minoritaires de PI et P2VP présentant des interfaces rectangulaires, arrangés avec une symétrie tétragonale, ouvrant la voie à des applications potentielles dans le domaine de nanolithographie
In this thesis, we focused on preparing nanostructured thin films from block copolymers and characterizing them by different techniques (AFM, TEM and GISAXS). The goal of the research is to produce original nanostructuration in thin films in order to consider the effect of confinement (limited amount of matter, interaction with surface ...) and to understand the phenomena occurring during structuration. The work includes the elaboration of thin films, their reorganization under solvent vapor and their characterization.Specifically, the thesis focused on the study of ISP linear triblock copolymers (PI-b-PS-b-P2VP) (neat or in blends) in thin films, already studied in volume by a partner laboratory of the Nagoya University. We developed adapted characterization methods to this type of polymer in thin film, such as an original method of GISAXS based on the selective staining of blocks by heavy elements (iodine, osmium). This allowed us to confirm the internal structure and the shape of interface of the minority domains and to observe original transitions between morphologies. The presence of wetting layers at both film interfaces (film / air and film / substrate) is a common feature for all systems.Firstly, neat triblocks located on the boundary between different morphologies on the phase diagram, were studied in thin film. Contrary to what was observed in volume, structural transitions (CYL-SPH and GYD-CYL) were observed in thin film. Particularly, the transition from an alternating gyroid structure having a Q214 symmetry to cylinders with symmetry P2mm (no typical hexagonal arrangement) represents, for triblock terpolymers, one of the major results of the thesis. The structural transition mechanism was elucidated by different characterization techniques showing an epitaxial relationship between the two phases. Secondly, we focused on the nanostructuration of triblock blends. We showed the possibility to obtain minority domains of PI and P2VP with rectangular interfaces, arranged with tetragonal symmetry, opening the way for potential applications in the field of nanolithography

Le but de ce travail a été l'étude de la technique d'électropolymérisation en vue d'obtenir les meilleurs films possibles pour l'application de protection contre la corrosion de métaux non nobles, par formation à leur surface de films de polymères.

Une étude bibliographique des divers cas déjà envisagés dans la littérature nous a permis de nous faire une opinion sur les composés susceptibles de présenter un intérêt et de choisir ceux que nous allions étudier. Cette étude bibliographique est assez volumineuse, de nombreux cas ayant été abordés par divers groupes de chercheurs partout dans le monde. Chacun des laboratoires s'est attaché à l'étude d'une propriété ou d'un paramètre particulier et il est assez difficile de synthétiser ces résultats. Nous avons relevé la liste des paramètres importants ayant une influence tant au point de vue des propriétés de conductivité des dépôts obtenus qu'en ce qui concerne leurs propriétés mécaniques, leur morphologie et leur adhérence au substrat. Ces paramètres comprennent la nature du substrat sur lequel on réalise l'électropolymérisation, le type de solvant, le type et la concentration en électrolyte support dans la solution, la concentration en monomère, les conditions de synthèse (mode potentiostatique, intensiostatique ou balayage en potentiel, durée de maintien du potentiel ou de la densité de courant, valeur de ce potentiel ou de cette densité de courant ou encore vitesse du balayage en potentiel, température), etc. Il faut d'ailleurs signaler qu'il existe bien entendu des influences croisées, entre autres entre la morphologie, la conductivité, la couleur et le taux de dopage.

Le choix d'un composé doit se faire en tenant compte des propriétés intrinsèques et de l'usage que l'on veut faire du polymère obtenu. Le choix des paramètres de synthèse devra résulter d'un compromis puisque plusieurs propriétés des films sont influencées en sens divers par ces paramètres. Par exemple, une structure plus régulière, et donc a priori plus conductrice, semble être obtenue par augmentation de la taille du contre-ion dopant dans le cas du pyrrole, mais le changement de nature du contre-ion peut également faire varier le taux d'insertion de ceux-ci dans le polymère, facteur qui aura aussi un effet sur la conductivité et sur la morphologie du film formé. Le type de substituant et sa position sur le monomère sont aussi à prendre en considération.

Le premier composé envisagé dans la partie expérimentale est la 2-vinylpyridine. Ce cas a été choisi parce qu'il s'agissait d'une électropolymérisation par réduction, méthode qui nous paraissait intéressante puisqu'elle présente l'avantage d'éviter tout risque d'oxydation du substrat lors de la formation du film. La réaction secondaire de dégagement d'hydrogène simultanée à la formation du film nous a cependant conduit à la conclusion que ce procédé n'offrait pas que des avantages.

Les films de poly-2-vinylpyridine formés semblent être constitués de polymères à assez faible degré de polymérisation et relativement adhérents au substrat métallique, mais présentent l'inconvénient d'être poreux et irréguliers du fait du dégagement d'hydrogène gazeux au cours du processus de synthèse. Ils sont constitués principalement de carbone et d'azote, et ce dans un rapport proche de celui du monomère. D'après les comparaisons des spectres infrarouge et ultraviolet de ces films avec ceux de poly-2-vinylpyridines obtenues par voie chimique, il s'agirait bien de ce composé. Bien que notre but n'était pas de déduire le mécanisme conduisant à la formation du polymère, nous avons pu déterminer que la réduction conduisant à la formation de ces dépôts nécessitait un échange d'un électron par molécule de monomère présente dans la chaîne polymérique. La conductivité électronique des films est faible. Leur croissance aurait plutôt lieu par un mécanisme ionique dans lequel des molécules de monomère pourraient diffuser au travers de la couche polyédrique déjà formée et qui, une fois chargées, pourraient soit se combiner à d'autres monomères au niveau du substrat, soit diffuser dans le film et aller former du polymère à sa surface, au contact de la solution d'électropolymérisation.

Parmi les composés qui peuvent être obtenus lors d'une électropolymérisation par oxydation, nous avons choisi le pyrrole qui nous a semblé particulièrement intéressant pour une application de protection vis-à-vis de la corrosion de l'acier doux. Ce dérivé hétéroaromatique possède en effet, par rapport à ses homologues thiophène et furanne, un potentiel d'oxydation relativement peu élevé, c'est-à-dire peu anodique. Il est de plus bien soluble dans des milieux aqueux et possède de bonnes propriétés d'adhérence pour autant qu'il soit formé en présence d'électrolyte conduisant à la passivation du fer. Son électropolymérisation n'est pas inhibée par la présence d'eau comme c'est le cas du thiophène. Les propriétés mécaniques du polypyrrole, meilleures que celles de la polyaniline qui est également obtenue par oxydation électrochimique, constituent également un élément en sa faveur.

Parmi les solutions dignes d'intérêt pour la polymérisation électrochimique de ce monomère, le cas de la solution aqueuse d'acide oxalique s'est révélé particulièrement intéressant. Elle permet en effet la formation d'un film passivant d'oxalate de fer sur le substrat, suivie d'un dépôt polymérique très adhérent, noir et conducteur.

Doctorat en sciences appliquées
info:eu-repo/semantics/nonPublished

Nanoscale particles based on the nature of building blocks often self-assemble into superstructures with distinctive spatial arrangements which can be used as functional materials for different application. Micro-phase separated hairy nanoparticle with helical hair can self-assemble to form supramolecular material which may mimic the properties and functions of the natural polymers such as protein and cellulose. Beside this hairy/core-shell nanoparticles also may find many applications such as in asymmetric catalysis, nano-fillers in tire and rubbers, model systems for biology, lithography and as sensors. In this work, we have successfully synthesized two hairy nanoparticles both of which has cross-linked polystyrene core with helical poly (3- methyl 4- vinyl pyridine) and poly (2- methoxystyrene) brushes respectively by living anionic polymerization via one-pot synthesis. NMR spectroscopy was used to determine that polymerization was successful and compositions of HNPs have the agreement with the targeted HNPs structure. By tailoring the architecture (functionalization of polymer chains, the degree of polymerization, grafting density) of HNPs, it is possible to control the final properties of the system. Differential Scanning Calorimetry was used to demonstrate the thermal properties of the synthesized HNPs which corresponds to polymer composition. Dynamic light scattering, SEM and AFM images were recorded to measure the particle size and morphology of the particles. Circular dichroism spectroscopy was used to determine the induced chirality of helical polymer brushes by complexing it with the small chiral molecule. SEM and AFM imaging were recorded to find out the morphology and hierarchically self-assembly of the hairy nanoparticle system. The synthesized particles may have great potential to successfully generate self-assembled suprastructures which can further solve the chiral resolution problem and can also find different applications.

Diese Arbeit liefert die Grundlage für intelligente Beschichtungen aus kovalent gebundenen Polymeren, sogenannten Polymerbürsten, mit Schichtdicken von wenigen Nanometern. Durch ihre Fähigkeit die Oberflächeneigenschaften je nach Umgebungstemperatur, pH Wert und Zusammensetzung zu ändern, kann die Adsorption von Biomolekülen auf eine einzigartige Art und Weise kontrolliert und reguliert werden. Die zusätzliche Modifizierung der Polymerbürsten mit Elektronenstrahlen ermöglicht die Generierung von Gradienten und erweitert die Anwendungsmöglichkeiten in vielfältigen Bereichen der interdisziplinären Forschung, wie z.B. in Hinblick auf das Lab-on-Chip Design oder die Biomedizin
Polymer brushes represent sensitive coatings with thicknesses of few nanometres and are interesting for interdisciplinary scientific research, e.g. for intelligent lab-on-chip design or biotechnology. It is demonstrated in this work, that polymer brushes are able to change their surface properties depending on the ambient conditions like solvent quality, temperature or pH value. This sensitivity highly influenced the adsorption of bio molecules. Especially mixed polymer brushes enabled the tuning of the adsorbed amount of various proteins and cells. To create surface gradients or structures in the different polymer brush surfaces, controlled electron beam modification was applied

Miniaturization has become a driving force in different areas of technology including microelectronics, sensoric- and bio-technologies and in fundamental science. Because of the well-known limitations of conventional lithographic methods, newly emerging bottom-up approach, utilizing self-assembly of various nanoobjects including single polymer molecules and carbon nanotubes constitutes a very promising alternative for fabrication of ultimately small devices. Carbon nanotubes are attractive materials for nanotechnology and hold much promise to revolutionize fundamental science in a investigation of phenomena, associated with the nanometer–sized objects.It was found in this work that grafted chains of poly(2-vinylpyridine) form a shell covering the carbon nanotubes that makes them dispersible in organic solvents and in acidic water (CNTs-g-P2VP).The positively charged poly(2-vinylpyridine) shell is responsible for the selective deposition of carbon nanotubes onto oppositely charged surfaces. It was established that the deposition CNTs-g-P2VP from aqueous dispersions at low pH is an effective method to prepare ultra-thin films with a tunable density of carbon nanotubes.It was shown that poly(2-vinylpyridine) grafted to carbon nanotubes is a universal support for the immobilization of various nanoclusters at the carbon nanotube's surface. Prussian Blue nanoparticles were selectively attached to the surface of CNTs-g-P2VP.Conducting polymer nanowires are another very promising kind of nanomaterials that could be also suitable for applications in nanodevices and nanosensors. In this work was developed a simple method to control the conformation and orientation of single adsorbed polyelectrolyte molecules by co-deposition with octylamine. A simple chemical route to conductive polypyrrole nanowires by the grafting of polypyrrole from molecules of polystyrensulfonic acid was developed. The dc conductivity of individual polypyrrole nanowires approaches the conductivity of polypyrole in bulk.The conductivity can be described using variable-range hopping model.

Miniaturization has become a driving force in different areas of technology including microelectronics, sensoric- and bio-technologies and in fundamental science. Because of the well-known limitations of conventional lithographic methods, newly emerging bottom-up approach, utilizing self-assembly of various nanoobjects including single polymer molecules and carbon nanotubes constitutes a very promising alternative for fabrication of ultimately small devices. Carbon nanotubes are attractive materials for nanotechnology and hold much promise to revolutionize fundamental science in a investigation of phenomena, associated with the nanometer–sized objects.It was found in this work that grafted chains of poly(2-vinylpyridine) form a shell covering the carbon nanotubes that makes them dispersible in organic solvents and in acidic water (CNTs-g-P2VP).The positively charged poly(2-vinylpyridine) shell is responsible for the selective deposition of carbon nanotubes onto oppositely charged surfaces. It was established that the deposition CNTs-g-P2VP from aqueous dispersions at low pH is an effective method to prepare ultra-thin films with a tunable density of carbon nanotubes.It was shown that poly(2-vinylpyridine) grafted to carbon nanotubes is a universal support for the immobilization of various nanoclusters at the carbon nanotube's surface. Prussian Blue nanoparticles were selectively attached to the surface of CNTs-g-P2VP.Conducting polymer nanowires are another very promising kind of nanomaterials that could be also suitable for applications in nanodevices and nanosensors. In this work was developed a simple method to control the conformation and orientation of single adsorbed polyelectrolyte molecules by co-deposition with octylamine. A simple chemical route to conductive polypyrrole nanowires by the grafting of polypyrrole from molecules of polystyrensulfonic acid was developed. The dc conductivity of individual polypyrrole nanowires approaches the conductivity of polypyrole in bulk.The conductivity can be described using variable-range hopping model.

碩士
國立臺灣大學
高分子科學與工程學研究所
93
To achieve high efficient organic photovoltaics, we propose to use self-assemble highly ordered block-copolymer as active layer to facilitate high charge carrier transport rate. In this study, we used anionic polymerization to synthesize block-copolymer poly(3-hexylthiophene)-b-poly(2-vinylpyridine)(P3HT-b-P2VP) with two compositions, 1: 2and 1: 49 (weight ratio). Their properties were studied by UV-vis, PL, TGA and TEM and compared them with pure P3HT and blend of P3HT-P2VP. In UV-vis and PL spectra, copolymers showed a blue-shift as compared with pure P3HT or blend. A red-shift was observed due to the aggregation of P3HT when a poor solvent, methanol, was added into pure P3HT or blend dissolved in THF. However, the optical spectra of block-copolymer did not change when they were dissolved either in tetrahydrofuran (THF) or methanol. The chemical bond between P3HT and P2VP in the copolymer has retarded the aggregation of P3HT in poor solvent. The decomposition temperatu of copolymer was greatly improved as compared with the neat P2VP, even with only a small amount of 2wt％ P3HT, from 352℃ to 381℃. This copolymer containg 2wt％ P3HT exhibitsa spherical morphology. In conclusion, we have synthesized P3HT-b-P2VP copolymer which will be used in photovoltaics.

碩士
國立中正大學
化學工程研究所
106
In this research, we report that an aluminum-capped isotactic poly(1-butene) was generated as the exclusive chain transfer reaction product by using Dichloro[rac-ethylenebis(indenyl)]-zirconium(IV) to mediate the isospecific polymerization of 1-butene in the presence of triethylaluminum as the chain transfer agent. The resulting aluminum-capped iP1B can be treated with oxygen and hydrogen peroxide to provide the hydroxy-capped iP1B (iP1B-OH) as the end-functionalized prepolymer. Consequently, the resulting iP1B-OH can be converted into the tosyl-capped iP1B (iP1B-OTs) by treated it with p-toluenesulfonyl chloride. The resulting tosyl-capped iP1B(iP1B-OTs) can be used to undergo coupling reaction with the living anionic P2VP so as to give the iP1B-block-P2VP diblock with precise microstructural and block length controls. This synthetic method is able to provide various iP1B-block-P2VP diblock copolymer samples, which have various volume fraction and stereoregularity controls. Accordingly, these block copolymer samples are able to self-assemble into various nanomorphologies as evidenced by Small Angle X-ray Scattering and Transmission Electron Microscopy studies. The resulting self-assembled nanostructures have an extremely narrow length of boundary and have the potential for use as nanotemplates. This research also focuses on the synthesis of isotactic poly(N-vinylcarbazole)(iPVK) through living cationic polymerization. In the presence of the initiating system consisting of CF3SO3H, nBu4NCl and ZnCl2, iPVK can be successfully prepared with good tacticity and molecular weight controls. We also demonstrated that the tacticity of iPVK can be precisely controlled by adding THF into the polymerization system.

碩士
國立中正大學
化學工程研究所
104
Polymers with tacticity have many special physical and chemical properties, and have found important industrial applications. In this report we focus on the syntheses and self-assembly studies of isotactic poly-2-vinylpyridine-based block copolymer (iP2VP-based block copolymer) as our previous studies have demonstrated that the combination of iP2VP with various chiral dopants can lead to the formation of unusual aggregated helical structure in solution as revealed by ICD experiments. In order to investigate the possibility of forming helical conformation in solid state block copolymer of iP2VP-block-PS is the target material of my research. Accordingly, a serious of iP2VP-based stereoregular block copolymers, isotactic poly(2-vinylpyridine)-b-polystyrene (iP2VP-b-PS), were prepared by atom transfer radical polymerization (ATRP) of an α-bromoester-terminated iP2VP macroinitiator with styrene. The α-bromoester-terminated iP2VP was prepared from the esterification of hydroxyl-capped iP2VP. The hydroxyl-capped iP2VP was prepared from hydroboration of allyl-capped iP2VP. The allyl-capped iP2VP was generated by using the allylbromide to quench the living anionic chain end of iP2VP. The method offers effective control over the stereoregularity of poly(2-vinylpyridine) and facilitates linking between blocks to provide stereoregular BCPs, which are capable of generating well-ordered nanostructures resulting from the self-assembly of stereoregular BCPs. Interestingly, the addition of chiral dopants into the iP2VP-b-PS diblock copolymer, which has the volume fraction for self-assembly in a cylindrical morphology, resulted in the formation of a unique quaternary-ordered helical structure as shown by TEM analyses.

碩士
國立中正大學
化學工程研究所
100
In this report, we demonstrated that various isotactic poly(2-vinyl pyridine) (iP2VP) samples with different degrees of isotacticity can be prepared by isospecific polymerization of 2-vinyl pyridine using tert-butylphenylmagesium bromide as the initiator. The isotacticty of these iP2VP samples can be controlled by the presence of different concentrition of coordination ligand (e.g., THF) on the polymerization solution. The resulting iP2VP samples were used to combine with various structures of chiral dopant to examine if the combination of stereoregualr (tactic) polyolefins and the chiral dopant can induced circular dichroism (ICD) driven by the formation of helical conformation along the main chain. The research focuses on two parts. First, syntheses and structural characterization of stereoregular P2VPs (including isotactic syndiotactic and atactic P2VP), which was used to combine with various structures of chiral dopant to examine the possibility of forming main chain helicity Second, preparation of iP2VP-based stereoregular diblock copolymers via post-block copolymerizartion of end-functionalized iP2VP using the end-functional group as the linkage.

碩士
國立中山大學
材料與光電科學學系研究所
101
In this study, the fabrication of block copolymer (BCP) photonic crystals with different microstructures including lamella, cylinder, gyroid and hexagonally perforated layer are conducted from the self-assembly of polystyrene-b-poly (2-vinyl pyridine) (PS-P2VP) BCP thin films. Transmission electron microscope (TEM) micrograph of high-molecular-weight PS-P2VP shows cylinder morphology from 1, 2-dichloroethane whereas low-molecular-weight PS-P2VP exhibits gyroid morphology form dichloromethane in bulk. Owing to the difference of solvent selectivity for PS and P2VP, various morphologies are obtained in as-spun PS-P2VP BCP thin films. Owing to poor solubility for P2VP resulted from strong interaction among pendent pyridines, the P2VP chains easily form micelles in the PS matrix in the as-spun PS-P2VP BCP thin films from PGMEA, THF, and chlorobenzene. Interestingly, the chloride-containing solvents such as chloroform, 1,1,2-trichloroethane, and 1, 2-dichloroethane may form protonation with pyridine so as to enhance the solubility for P2VP, such that microphase-separated gyroid morphology can be observed in the as-spun BCP thin films as evidenced by TEM and the grazing-incidence ultra-small angle X-ray scattering. By solvent annealing, interesting phase behaviors of the PS-P2VP BCP thin films can be found. After solvent annealing by toluene, P2VP micelles in the PS matrix can be obtained due to poor solubility for P2VP. By contrast, phase transitions from the as-spun micelle or gyroid to lamellae can be found after solvent annealing by PS-selective solvents such as 1, 1, 2-trichloroethane (TCE) or chloroform. Accordingly, large-area lamellar microstructures with parallel orientation to glass substrate can be accomplished due to substrate- and solvent-induced microstructural orientation. Most interestingly, a phase transition from the as-spun gyroid to well-oriented hexagonally perforated layer (HPL) phase can be obtained in the PS-P2VP BCP thin film after solvent annealing by TCE. By absorption of ethanol, the selective swelling of the P2VP microdomian in the PS-P2VP BCP thin film may give significant red shift of the reflective wavelength, such that photonic bandgaps in visible spectrum can be carried out. The UV-Vis spectra of the gyroid-forming PS-P2VP photonic crystal exhibits unique solvatochromic behavior by absorption of ethanol, as evidenced by the characteristic reflective wavelength ratio of √6 ∶ √8 . Surprisingly, the HPL-forming BCP photonic crystal reveals that the multiple reflectivity bands cover whole visible spectrum with the accompanying decrease of reflective intensity, resulting in white reflective color mixed with purple. As a result, the BCP photonic reflectors with various microstructures can be fabricated from the self-assembly of the PS-P2VP BCP thin films. The significantly different optical properties associated with the microstructural shapes are promising to be applied in various applications.

碩士
國立中正大學
化學工程研究所
102
Stereoegular tactic Polymers have many unique physical and chemical properties and applications, and hence have drawn tremendous research attentions. In this report, stereoregualr isotactic poly-2-vinylpyridine (iP2VP) was synthesized and used to combine with various chiral dopants to examine if the combination of stereoregualr (tactic) polyolefins and chiral dopants can induced circular dichroism (ICD) driven by the formation of helical conformation along the iP2VP main chain. In the syntheses of iP2VP, two kinds of Grignard reagents, including para-3-butenylphenylmagnesium bromide and 4-tertbutylphenylmagnesium bromide, were synthesized and used as initiators. Our results indicates that the polymerization of 2-vinylpyridine by using the 2-vinylpyridine as the initiator offers the production of iP2VP with exceptional high isotacticity control (mmmm > 90 %). We also demonstrated that the isospecific polymerization of 2-vinylpyridine initiated by 4-tertbutylphenylmagnesium bromide showed a living polymerization pathway. Accordingly, iP2VP-based block copolymers can be prepared through the living polymeriaztion,funtionalization,and then block copolymerization pathways. The research focuses on two parts, first, syntheses and structural characterization of new Grignard reagent and second, preparations of iP2VP-based stereoregular diblock copolymers. The resulting iP2VP-based diblock copolymers can be used to combine with chiral dopant to examine the possibility of forming helical assembly via the molecular recognition processes。

Diese Arbeit liefert die Grundlage für intelligente Beschichtungen aus kovalent gebundenen Polymeren, sogenannten Polymerbürsten, mit Schichtdicken von wenigen Nanometern. Durch ihre Fähigkeit die Oberflächeneigenschaften je nach Umgebungstemperatur, pH Wert und Zusammensetzung zu ändern, kann die Adsorption von Biomolekülen auf eine einzigartige Art und Weise kontrolliert und reguliert werden. Die zusätzliche Modifizierung der Polymerbürsten mit Elektronenstrahlen ermöglicht die Generierung von Gradienten und erweitert die Anwendungsmöglichkeiten in vielfältigen Bereichen der interdisziplinären Forschung, wie z.B. in Hinblick auf das Lab-on-Chip Design oder die Biomedizin.
Polymer brushes represent sensitive coatings with thicknesses of few nanometres and are interesting for interdisciplinary scientific research, e.g. for intelligent lab-on-chip design or biotechnology. It is demonstrated in this work, that polymer brushes are able to change their surface properties depending on the ambient conditions like solvent quality, temperature or pH value. This sensitivity highly influenced the adsorption of bio molecules. Especially mixed polymer brushes enabled the tuning of the adsorbed amount of various proteins and cells. To create surface gradients or structures in the different polymer brush surfaces, controlled electron beam modification was applied.