Thèses sur le sujet « Polymers based materials »

Este trabalho estuda a influência do carbonato de cálcio (CaCO3) nas propriedades mecânicas e na formação da fase cristalina beta do polipropileno (PP). Com o intuito de produzir amostras para o estudo, foi feita uma análise preliminar sobre o enxerto do anidrido maléico no polipropileno, porque este material graftizado (PP-g-MA) contribui significativamente em blendas e compósitos ao melhorar a adesão superficial entre o PP e o CaCO3. Foram estudados dois métodos de obtenção deste produto (PP-g-MA) utilizando-se peróxido orgânico e os produtos obtidos foram caracterizados e comparados. Apesar dos resultados das análises feitas por calorimetria diferencial exploratória (DSC), análise termogravimétrica (TGA), microscopia eletrônica de varredura (MEV) e espectroscopia de energia dispersiva (EDS) indicarem importantes diferenças entre os dois métodos, a análise por espectroscopia no infravermelho (FTIR) trouxe conclusões sobre a eficácia dos métodos de graftização. Duas séries de compósitos a base de PP contendo CaCO3 foram produzidos por mistura intensiva em fusão (misturador Drais), uma contendo PP-g-MA e a outra sem. Quatro tipos de CaCO3 foram utilizados, diâmetros de 0,9 µm, 2,5 µm e 3 µm, sendo que o CaCO3 0,9 µm apresentou-se com superfície tratada e não-tratada. A concentração de CaCO3 foi mantida em 5% e a de PP-g-MA em 5% quando presente. Os compósitos foram submetidos a testes de resistência à tração, módulo na flexão e resistência ao impacto em duas temperaturas. As amostras contendo menores tamanhos de partículas de CaCO3 e PP-g-MA apresentaram melhora sinérgica na resistência mecânica, em que aumentos da resistência a impacto e da resistência a flexão foram observados. A análise da fase cristalina beta nestas amostras foi feita utilizando-se DSC e difratometria de raios-x. Também foi analisada a influência da adesão superficial entre a carga e a matriz de PP, quanto maior a adesão superficial e menor o tamanho de partícula do CaCO3, maior a formação da fase cristalina beta, o que contribuiu para a sinergia entre todas as propriedades mecânicas avaliadas neste trabalho.
This study aimed at improving the comprehension of the influence of calcium carbonate (CaCO3) in the formation of the beta crystalline phase of polypropylene (PP), as well as the changes in the mechanical properties of this polymer. A preliminary analysis of the grafting of the maleic anhydride in the polypropylene was carried out in order to produce specimens for the study, owing to the fact that this grafted polypropylene (PP-g-MA) contributes substantially to change the polarity of the polymer and therefore, enhance the superficial adhesion between PP and CaCO3. Two grafting methods using organic peroxide were studied. The grafted copolymers were analyzed by DSC, TGA, SEM, EDS, and FTIR. Two series of PP composites containing CaCO3 were produced by intensive melt mixing (Drais mixer), one of them having MA-g-PP. Four types of CaCO3 were used, which diameters were 0.9 µm, 2.5 µm and 3 µm, though the CaCO3 0.9 µm was surface-treated and non-treated. The concentration of CaCO3 was maintained at 5% and PP-g-MA at 5 % also, when present. The composites were tested for tensile strength, flexural modulus and impact strength (at two temperatures). Samples containing smaller particle sized CaCO3 and PP-g-MA showed synergistic improvement in the mechanical strength, and increases in the impact resistance and flexural strength were observed. Analysis of the beta crystal phase in these samples was performed using DSC and x-ray diffractometry. The influence of superficial adhesion between CaCO3 and PP was also analyzed, higher concentration of the beta crystalline phase was observed for better surface adhesion and smaller CaCO3 particle size, which contributed to the synergy between all the mechanical properties evaluated in this work.

Le Le but de ce sujet doctoral est la synthèse et la caractérisation de nouveaux polymères de coordination à base de lanthanides et présentant des propriétés de porosité ou de luminescence intéressantes. Nous avons synthétisé deux types d'échantillons : des monocristaux et des poudres microcristallines. Sur la base des données de diffraction des rayon-X par le monocristal, les structures cristallines ont été résolues. La stabilité thermique, la porosité et les propriétés de luminescence ont été étudiées grâce aux poudres microcristallines obtenues. Cinq systèmes de polymères de coordination ont été étudiés : Ln-ATPT (H2ATPT = acide 2-aminoterephthalique), Ln-AIP (H2AIP = acide 5-aminoisophtalique), Ln-OBA (H2OBA = acide 4,4'-oxybis(benzoates)), Ln-BTEC (H4BTEC = acide 1,2,4,5-benzènetétracarboxylique) et Ln-BPDC (H2BPDC = acide 4,4'-biphényldicarboxylique). Quinze familles de monocristaux ont été obtenues par diffusions en tubes en U à travers des gels physiques ou chimiques, par diffusion en tubes en H a travers de l'eau distillée, ou par évaporation lente des filtrats obtenus après la synthèse des poudres microcristallines. Les synthèses des poudres microcristallines ont été réalisées à 2°C, température ambiante, 40°C et 90°C. Les poudres ont été classées en familles en fonction de leurs diagrammes de diffraction des rayon-X. Leurs stabilités thermiques ont été mesurées par analyse thermo-gravimétrique (TGA) et diffraction des rayons X dépendante de la température. Leurs propriétés de luminescence ont été étudiées à l'état solide. Les porosités ont été estimées par une méthode développée au laboratoire
This doctoral subject aims to synthesize and characterize new porous or luminescent coordination polymers based on lanthanides ions. There are two kinds of samples used in this work : single crystals and microcrystalline powders. The former ones are synthesized for structural analysis on the basis of X-ray diffraction data. The later ones characterized by X-ray powder diffraction (XRPD) are prepared for analyzing thermal stability, luminescence properties and porosity. In this work, five systems were explored involving five multi-carboxylate ligands: H2ATPT (2-aminoterephthalic acid), H2AIP (5-aminoisophthalic acid), H2OBA (4,4’-oxybis(benzoates) acid), H4BTEC (1,2,4,5-benzenetetracarboxylic acid) and H2BPDC (4,4’-biphenyldicarboxylic acid). As a result, 15 series of single crystals were obtained by slow diffusions in U-shaped tubes through physical or chemical gels, by slow diffusions in H-shaped tubes through distilled water or by evaporation of the filtrate obtained after the synthesis of the microcrystalline powders. The microcrystalline powders were synthesized at 2°C, room temperature, 40°C and 90°C. All the powders were classified in different families according to their XRPD diagrams. Their thermal stabilities were evaluated by thermo-gravimetric analysis (TGA) and temperature depending X-ray diffraction (TDXD). Their luminescent properties were studied by solid-state luminescent measurements. Their porosities were estimated by a computational method developed in our laboratory

The ability to programme and manipulate small changes at the molecular level to elicit a dramatically enhanced macroscopic response makes “stimuli-responsive” materials a fascinating topic of study. This work seeks to manipulate the solubility switch associated with polymers exhibiting a Lower Critical Solution Temperature without a temperature change (‘isothermally’). This concept, as overviewed in Chapter 1, has attractive applications in biological settings where variations in in vivo microenvironments may be used to produce increasingly targeted delivery vehicles, and to mediate cell membrane interactions. Using controlled radical polymerisation, pre-designed backbones, end-group(s) or side-chains can be targeted to control the hydrophilic-hydrophobic balance of a thermo-responsive system. Chapters 2 and 3 investigate this concept, using the chemical reduction of a functional polymer backbone or end-group to trigger isothermal polymer precipitation or solubilisation in linear and nanoparticle systems respectively. Chapter 4 applies a metal-ligand binding motif, prevalent in bacteria, to end-functional polymers as an alternative means of promoting isothermal polymer precipitation. This binding motif is then transferred to a nanoparticle system in Chapter 5, and used for the first time to prepare an optical, particle-based biosensor for the detection of physiologically relevant iron concentrations. Finally, Chapter 6 describes the enzymatic degradation of a polymer side-chain as a means of triggering isothermal precipitation and considers its potential to mediate cellular uptake. In summary, a series of functionalised polymers and nanoparticles have been synthesised and their (isothermal) responses characterised. These materials may have exciting potential in the emerging field of nanomedicine.

Foam-like aerogels based on biodegradable polymers and sodium montmorillonite (Na+-MMT) clay were prepared through an environmentally friendly freeze-drying process. Both synthesized and bio-based polymers were utilized in this thesis, including polyvinyl alcohol (PVOH), carboxylmethylcellulose (CMC), xanthan gum, agar, Arabic gum and starch. The morphologies of aerogels were characterized using scanning electron microscopy. The mechanical properties investigation included compression and impact tests. Porosities and solid densities were measured using a helium pycnometer while the pore size distribution was determined by automated mercury porosimeters. Most of polymer-clay aerogels exhibited porous and layered structures that were formed via ice templating. However, high viscosity of the precursor solution may break the layered architecture by retarding the formation of ice crystals (e.g. 2.5 wt% agar aqueous solution). The structures as well as the properties of aerogels were mainly influenced by polymer/clay proportion. Polymer molecules play a role of glue linking the clay nanoparticles, improving the structural integrity and hence the mechanical performance of the aerogels. On the other hand, clay platelets serve as a physical barrier that increases the heat endurance. Recycled cellulose fibers (RCF) that were isolated from waste paper pulp were also used to prepare bio-based aerogels. Adding another biopolymer CMC into RCF aerogels, the resultant RCF-CMC composite aerogels showed different microstructures and enhanced mechanical properties. Physical blending and chemical crosslinking were used to tailor the mechanical properties of xanthan gum/clay aerogels and starch/clay aerogels, respectively. Blending agar with xanthan gum in aqueous solution, the resultant aerogels displayed a significant improvement in mechanical properties compared with those containing a single biopolymer. Moreover, they exhibited tunable microstructures and mechanical properties by changing agar/xanthan gum ratio in the aerogels. As to starch/clay aerogels, the incorporation of glutaraldehyde enhanced the structural integrity and mechanical properties of the aerogels through crosslinking reaction between glutaraldehyde and starch molecules, which was proved by Fourier-Transform infrared (FT-IR) spectroscopy analysis. The evaluation of the flammability of aerogels was conducted with a cone colorimeter while the thermal stability was obtained from the results of thermogravimetric analysis. In regard to PVOH-clay aerogel, different types of flame retardant fillers, such as aluminum trihydroxide (ALH), ammonium polyphosphate (APP), silica gel and potassium carbonate, were adopted to modify their flame retardant properties. The results showed that ALH addition enhanced the flame retardancy as well as mechanical properties. For RCF-CMC aerogels, APP and clay played a synergetic effect on the flame retardancy and thermal stability.
En esta Tesis se han preparado diversos aerogeles usando polímeros biodegradables como matriz y arcilla como refuerzo, a través de un proceso de fabricación amigable con el medio ambiente. Los polímeros empleados han sido tanto de origen natural (goma árabiga, agar-agar, goma xantana, almidón) o sintéticos como la carboximetilcelulosa (CMC) o el alcohol polivinílico. Los compuestos formados se han caracterizado a través de diferentes técnicas con el objeto de relacionar las morfologías generadas con las propiedades térmicas y mecánicas resultantes. La gran mayoría de los aerogeles polímero/arcilla exhiben una estructura porosa y laminar que se forma a raíz de la liofilización. Sin embargo, se ha apreciado que altas viscosidades en la solución precursora puede romper la arquitectura laminar al retardar el crecimiento de los cristales de hielo (ej. Solución acuosa de 2.5 % peso de agar). La estructura y las propiedades de los aerogeles están asimismo y en general influenciados por la relación polímero/arcilla. En estos sistemas, las moléculas de polímero actúan a manera de pegamento uniendo las partículas de arcilla, incrementando de esa manera notablemente la capacidad mecánica de los aerogeles. Por otro lado la arcilla actúa entre otras formas, como barrera térmica incrementando la resistencia térmica y al fuego de las espumas formadas. Dentro de este trabajo se han empleado fibras de celulosa recicladas de residuos de papel en un intento de preparar bio-aerogeles a partir de material de desecho. La unión de estas fibras con CMC permitió obtener aerogeles con propiedades mejoradas y la posibilidad de emplear estos residuos en un segundo uso. Además del mezclado físico, en algunos casos se ha realizado una reacción de entrecruzamiento para ajustar las propiedades finales, como en el caso de los aerogeles goma xantana/arcilla o almidón/arcilla. La mezcla de agar con goma xantana en solución acuosa resultó en un notable aumento de propiedades con respecto a las composiciones que contenían un único polímero, debido al cambio morfológico inducido, pasando de una estructura laminar a una de tipo panal de abeja (honeycomb). De esta forma y a través de la relación entre estos dos polímeros naturales ha sido posible balancear y definir las propiedades finales deseadas para el aerogel. En los sistemas almidón/arcilla el entrecruzamiento se ha conseguido a través de un agente externo como el glutaraldehido. Atendiendo a su posible uso final, unas de las propiedades más relevantes en los aerogeles que se ha estudiado ha sido la estabilidad térmica y la resistencia al fuego. En este sentido, se han preparado sistemas basados en Polivinilalcohol/arcilla modificados con diferentes retardantes de llama. De los diversos aditivos probados la combinación con hidróxido de aluminio ha mostrado un efecto sinérgico incrementando tanto de la resistencia a fuego como las propiedades mecánicas. En los sistemas basados en celulosa la presencia de polifosfato de amonio y arcilla ha demostrado así mismo un efecto potenciador de la estabilidad térmica y en el retardo de llama.

The present PhD thesis deals with the synthesis and characterization of functionalized ferrocenes with up to four aldehyde and vinyl groups and their usage as monomers to produce novel ferrocene-based oligomers with conjugated backbones via ADMET (acyclic diene metathesis) and HWE (Horner-Wadsworth-Emmons) reaction protocols. In addition, ferrocene-containing polymers (linear, cross-linked and co-polymers) with aliphatic backbones generated by anionic bulk and solution polymerization routes, and their electrochemistry behaviors were studied. The main aspects of this work lies in the enhancement of the electrical properties of the ferrocene-based materials (oligomers or polymers) by varying the polymer backbone, providing multi-functionalities for cross-linking and co-polymerization processes and thereby increasing the molecular weight of the products, furthermore, the application as electro-active materials, especially for the charge storage purposes is discussed. High monomer consumption, relatively high molar mass as well as longer chains were achieved by bulk protocol. Electrochemical measurements (CV) reveals that formyl-ferrocenes bearing more than two formyl functionalities are very electron poor materials and easily decomposes upon oxidation. Reducing the measurement temperature and the usage of [NnBu4][B(C6F5)4] as electrolyte allowed for reliable behavior. A linear correlation between the redox potential and the number of the formyl functionalities was found. Multicyclic measurements showed that ferrocenyl / ferrocenium redox couples in the polymeric materials are stable at least up to 100 cycles. The spectro-electrochemical studies show that the conjugated materials (oligomers) have electron transfer interactions (IVCT) through the chains, while the aliphatic backbone between the ferrocenyl units (poly vinylferrocene materials) hindered the metal-metal coupling along the chain and only a ligand-to-metal charge transfer excitation could be observed
Die vorliegende Doktorarbeit beschäftigt sich mit Synthese und Charakterisierung von funktionalisierten Ferrocenen mit bis zu vier Aldehyd- und Vinylgruppen und ihrer Verwendung als Monomere für neuartige ferrocenbasierte Oligomere mit konjugiertem Rückgrat unter ADMET (acyclic diene metathesis) und HWE- (Horner-Wadsworth-Emmons) Reaktionsbedingungen. Zusätzlich wurden ferrocenhaltige Polymere mit einem aliphatischen Rückgrat durch Polymerisation mit und ohne Lösemittel hergestellt und ihr elektrochemisches Verhalten untersucht. Das Hauptaugenmerk dieser Arbeit liegt in der Optimierung der elektrochemischen Eigenschaften der ferrocenbasierten Materialien (Oligomere oder Polymere) durch Variation des Polymerrückgrats, welche zahlreiche funktionelle Gruppen für die vernetzte Polymerisation und die Co-Polymerisation liefert. Durch diesen Prozess wird das molekulare Gewicht erhöht. Zusätzlich wird die Verwendung als elektroaktive Materialien insbesondere für die Energiespeichertechnik diskutiert. Durch lösungsmittelfreie Reaktionsbedingungen wurden ein hoher Monomerumsatz, relativ hohe molare Massen und zugleich längere Polymerketten erzielt. Elektrochemische Messungen (CV) zeigten, dass Ferrocenmoleküle mit mehr als zwei Formylgruppen die Elektronendichte an der Ferrocenyleinheit verringern und bei Oxidation leicht zersetzt werden. Erniedrigung der Messtemperatur und die Verwendung des nur schwach koordinierenden Leitsalzes [NnBu4][B(C6F5)4] führten zu aussagekräftigen Ergebnissen. Weiterhin konnte ein linearer Zusammenhang zwischen dem Redoxpotential und der Anzahl der Formyleinheiten aufgezeigt werden. Mutlizyklische Messungen bestätigten, dass das Ferrocen / Ferrocenium-Redoxpaar mindestens 100 Zyklen stabil ist. Mittels spektroelectrochemisches Messungen konnte gezeigt werden, dass konjungierte (oligomere) Verbindungen eine elektronische Wechselwirkung (IVCT) aufweisen, während aliphatische Rückgrade eine Wechselwirkung zwischen Ferrocen / Ferrocenium (polyvinylferrocenbasierte Materialien) verhindern und nur ein LMCT Übergang (Ligand zu Metall Charge-Transfer) beobachtet werden kann

Self-healing materials have received considerable development in the last decade. Recent results have demonstrated healing in polymeric materials via a chemical reaction using a healing agent or response to thermal treatment. The goal of this research is to develop a new composite material, for application in wire insulation, that can detect damage and heal itself using resistance heating. The composite material is composed of a conductive network embedded in a polymer matrix. The conductive network is used for damage detection and resistive heating. A matrix material is used that melts when heated and flows to fill damage. External electronic circuitry is used to implement a damage detection algorithm and apply current for resistive heating. Surlyn 8940 is chosen as the polymer matrix and carbon fibers are selected for the resistive heating elements. Methods for melt processing Surlyn are developed and used to produce Surlyn films and composite samples where carbon fiber is embedded in a Surlyn matrix. A finite element model of the resistive heating process is developed to predict the temperature distribution. Thermal imaging is used to characterize resistive heating while optical microscopy and tensile testing are used to characterize healing. Damage detection using capacitive measurements is demonstrated and characterized. The self-healing composite is placed on top of another conductive material such as in the wire insulation application. Capacitance measurements are made using the conductive network inside the composite is used as one electrode and the wide conductor as the second electrode.
Master of Science

Dithienopyrrole-based conjugated materials, including oligomers and polymers, for potential organic electronic applications, were designed, synthesized and characterized. The optical and electrochemical properties of these materials were investigated, and their structure-property relationships were studied. Some of the materials can be oxidized (or reduced) chemically or electrochemically. Furthermore, the utility of these materials in organic electronic devices, such as OFETs and OPVs, were assessed. In OFETs, they can function as hole-transport materials with mobilities up to 4.8 × 10-2 cm2/(Vs), and one example serves as an ambipolar material with comparable hole and electron mobilities of 1.2 × 10-3 and 5.8 ×10-4 cm2/(Vs), respectively. Some of the materials can also be used as electron donors in OPVs in conjunction with PCBM, and exhibited power conversion efficiencies up to 1.4% after optimizations. They may also be used in other applications such as electrochromic devices, photodetectors, and optical limiting.

This project was focused on the synthesis of novel Polymers of Intrinsic Microporosity (PIMs) that are soluble in common low boiling point solvents so that self-standing films can be prepared for gas permeability measurements. The common building unit of these novel PIMs was triptycene and its derivatives. Modification of these triptycene compounds enabled the alteration of the polymeric backbone, so that we could tune the gas permeability properties. Modifications included the substitution of different functional groups (e.g. addition of methyl groups) and also the extension via benzoannulation of the triptycene structure. The synthesis of the PIMs was based around three different polymerisation techniques. The first one involved the formation of triptycene-based polyimides (PIs) using a triptycene based dianhydride, prepared in a multistep synthesis. Shorter and cheaper synthetic routes were attempted, but all to no avail. The resulting triptycene monomer was reacted with a variety of commercial and non-commercial bisanilines for the formation of several PIM-PIs, all exhibiting different performances. Robust self-standing films were obtained for two of these PIM polyimides. In addition to the formation of polyimides, the synthesis of Tröger’s Base (TB) polymers, also based on triptycene components, were achieved. This type of polymerisation involves the reaction between a “bisaniline” monomer and a source of “formaldehyde”, such as dimethoxymethane (DMM), in a strong acid media, typically trifluoroacetic acid (TFA). Modification of these triptycene-based bisanilines has led to the formation of TB-PIMs, all with distinctive gas permeation properties. TB-PIM copolymers (reaction between two different bisaniline monomers with DMM and TFA) were synthesised in an attempt to further tune the performance of the polymers. Finally, the preparation of polybenzodioxan polymers based around extended triptycene monomers (i.e. benzotriptycenes) was studied. By using a variety of substituted benzotriptycene biscatechol monomers and performing the polymerisation using tetrafluoroterephthalonitrile, in the presence of K2CO3, the synthesis of a series of substituted benzotriptycene polybenzodioxane polymers was successfully achieved and the polymers showed enhanced gas permeation properties.

Organic-based electronic devices have received considerable attention because of their presumable advantages over traditional inorganic-based electronics, such as low cost, flexibility, and applicability for large area production. Because of the possible commercialization of electronic products based on organic conducting materials, it is important to develop a variety of organic semiconductors (OSCs) that are categorized as hole transporting (p-type), electron-transporting (n-type) or ambipolar transporting (both hole and electron). P-type OSCs have been the most thoroughly studied. N-type semiconductors are much less common and the charge carrier mobilities have lagged considerably behind their p-type counterparts. Fullerene-based materials are currently the most widely used n-type semiconductors in OPVs. The cage-like structure associated with buckminsterfullerene is made of fused six- and five-member rings. Acenaphthylene is a basic fragment of C60 and has shown potential as a valuable building block for n-type OSCs. To utilize this promising structure, the acenaphthylene unit has been incorporated into a variety of molecular structures to produce both small molecule and polymeric materials. We started with the study of fully unsaturated tetraquinane derivatives, which contain four linearly fused five-membered rings. The desired diacenaphthylpentalenes were synthesized via a palladium-catalyzed dimerization of 1-iodo-2-arylethynyl-acenaphthylenes. The compounds are benchtop and solution stable and behave as hole-transporting or ambipolar semiconductors in organic field effect transistors. The X-ray crystal structure demonstrates the importance the fused naphthalene units as they stabilize the pentalene core with an extended π-framework. The tetraquinane derivatives possess high optical gap materials owing to a forbidden HOMO to LUMO transition, yet have narrow electrochemical gaps and are reduced at small negative potentials giving lowest unoccupied molecular energy levels of -3.57 to -3.74 eV. In addition to the unsaturated tetraquinane derivatives, this thesis also includes work on the creation of macrocycles containing acenaphthylene or cyclopenta[cd]perylene units. The stabilized annulenes, with rigid and π-conjugated structures, have potential application as discotic liquid crystals and porous organic solid. 1H NMR and low resolution mass spectra gave solid proof that a target macrocycle was synthesized; however, the tedious work up and limited purification techniques did not enable large scale synthesis. The investigation of new donor-acceptor copolymers incorporating acenaphthylene or cyclopenta[cd]perylene units was also explored. Since the molecular scaffolds of the desired polymers have structural resemblance and electron affinities compared to bis-imide rylene dyes (NDI and PDI), the resulting materials have relavence for a varety of OSC based devicse. UV-Vis spectroscopy and cyclic voltammetry were utilized to probe the photoelectronic properties of these materials.

ELECTROCHROMIC MATERIALS represent a special and intriguing class of redox active compounds, characterized by a drastic change in their optical properties upon reduction or oxidation. Many aromatic organic molecules, monomeric or polymeric, are electrochromic, and some of them can even outperform their inorganic counterparts in some aspects. In particular, the ability to easily tune the colour of the redox states, represent an invaluable asset of this class of compounds. Among the many different organic electrochromic materials, those possessing a highly transmissive colourless state have gained much attention for their potential application in smart windows, self-darkening eyeglasses, anti-glare car rearview mirrors, etc. Moreover, a neutral tint of the coloured form is desired for these applications in order to avoid colour distortion. This work develops a novel class of discrete and polymeric electrochromic materials based on the violene structural motif. In particular, the class of diazinium ethenes has been explored and the electrochromic properties of the derivatives have been evaluated by electrochemical measures. These compounds have shown to undergo a reversible two-electron transfer, accompanied by a colourless −)−−*− coloured electrochromic behaviour with high contrast in the 450-550nm region. The new violene discrete electrochromes were then incorporated in a poly(3,4- ethylenedioxythiophene) (PEDOT) matrix, developing an hybrid multichromophoric system that take advantage of the characteristics of both systems to achieve a panchromatic absorption in the reduced state and a very high contrast value. In particular, the incorporation of the violene electrochromes has been obtained linking them, through a tether, to an EDOT moiety, and subsequently polymerizing (chemically or electrochemically) themodifiedmonomers (ISOx). The obtained polymers, poly(ISOx), display colourless highly transmissive oxidized states and reduced states with an extended colour palette (violet-red, purple and brown). Moreover, an impressive electrochromic contrast in the visible region has been achieved, with calculated luminance variations as high as 72%. This result represent a big improvement compared to the literature reported 52% for a system with comparable spectral characteristics. In the last chapter, a novel and versatile synthon for EDOT derivatization, exo-methylene-EDOT, is described and characterized along with some of its derivatives. This compound readily react with alcohols under acid catalysis to give Markovnikov addition products, and with thiols, in presence of radical initiators or photochemically, to give sulfides (anti-Markovnikov products). The latter reactivity proved to be very interesting for the extreme rapidity and high conversions achieved. An EDOT derivative with a pendant trialkoxysilane moiety has been prepared using 3-mercaptopropyltrimetoxysilane as thiol counterpart. This compound was subsequently tested as reagent for the functionalization of surfaces with EDOT moieties. An alternative approach, relying on an in situ thiol-ene reaction between exo-methylene-EDOT and a thiol functionalized surface, was also tested to achieve such functionalization. Both procedures have demonstrated to provide the desired surface modification. This kind of ultra thin films could find application as coupling layers for the deposition of PEDOT-like polymers on metal oxides, solving the adhesion problems that hamper the long-term operation of the devices.

Thesis ( Ph.D.)--Cleveland State University, 2009.
Abstract. Title from PDF t.p. (viewed on July 22, 2009). Includes bibliographical references (p. 159-160). Available online via the OhioLINK ETD Center and also available in print.

The class of compounds known as the dibenzotetraaza[14]annulenes have been of particular interest over the past 25 years, with the initial impetus for research being the relationship they hold with the naturally occuring porphyrins. The main aim of the work undertaken was to establish the potential of dibenzotetraaza[14]annulene type systems for the development of novel materials whose applicable behaviour was likely to fall into one of the following three categories; liquid crystals, organic conductors, and chelating systems. Additionally the chemistry involved with the synthesis of these types of materials was interesting in its own right and provided a platform for the author to increase his own knowledge of chemistry. The research undertaken may be broadly classified into the following areas: 1. The preparation of linear Schiff base polymers, 2. The preparation of dibenzotetraaza[14]annulenes (metal complexes and free ligands), 3. The preparation of 1-D and 2-D unsymmetrical macrocyclic complexes, and 4. The preparation of polymeric materials incorporating dibenzotetraaza[14]annulenes both as part of the polymeric backbone and as pendant side chains in a comb type polymer. 1. The preparation of linear Schiff base polymers. The Schiff base condensation of phenylenediamines with malondialdehydes has enabled the preparation of materials of the type illustrated below. [chemical formula]. Examination of the materials by differential scanning calorimetry has shown that many of the materials exhibit interesting thermal transitions from one crystalline state to another. However the use of thermal microscopy has not shown any of these phases to be liquid crystalline transitions. 2. The preparation of dibenzotetraaza[14]annulenes (metal complexes and free ligands). An extensive array of dibenzotetraaza[14]annulenes have been prepared, generally by a one step process involving the reaction of ortho-phenylenediamine and various 2-substituted malondialdehydes in the presence of a suitable acid catalyst and solvent. [chemical formula]. 3. The preparation of 1-D and 2-D unsymmetrical macrocyclic complexes. The introduction of unsymmetricality into the dibenzotetraaza[14]annulenes has been of interest since dipole-dipole interactions between molecules may lead to enhanced crystalline stacking, which in turn has a direct effect on any liquid crystalline or semiconducting properties the material may exhibit. Consequently the preparation of unsymmetrical dibenzotetraaza[14]annulenes has been undertaken, which has often required extended stepwise synthetic reaction pathways involving the use of protecting reagents. Small quantities of pure materials have been prepared and are believed to be the first of their type. 4. The preparation of polymeric dibenzotetraaza[14]annulenes. The incorporation of dibenzotetraaza[14]annulenes into a polymeric system has been examined in two ways. The initial study concentrated on the incorporation of the macrocycle directly into the polymer backbone and involved the reaction of suitably functionalised dibenzotetraaza[14]annulenes with linking groups such as para-phenylenediamine. The additional study has focussed on a method of forming polymers which include the macrocyclic complexes as pendant side chains in a comb type polymeric arrangement (illustrated below). [chemical formula]. At present the prepartion of a polymer of this type has not been achieved. However an extensive study into the attachment of groups to the macrocycles which are capable of undergoing polymerisation has been undertaken which has established the potential use of the Gabriel synthesis of amines and the Wittig reaction as potential methods of attachment.

Nowadays, the ability to pattern surfaces on the micro- and nano- scale is the basis for a wide range of research fields. Over last few decades, a lot of processing technologies offer the possibility to fabricate complex 2D and 3D polymeric designs which are mostly static in nature since they cannot be physically and chemically modified once fabricated. The aim of the present thesis is to overcome such a limitation, exploiting stimuli-responsive materials (Chapter I). We allow to engineer polymeric architectures adding interesting functionalities, by providing an active manipulation of pre-structured systems, which could be helpfully in a wide variety of applications, such as biosensing and cell conditioning. In the first part of the present dissertation (Chapter II), a thermos-sensitive material is employed. We investigate the thermo-responsive behavior of Poly(N-isopropylacrylamide) (pNIPAAm)-based crosslinkable hydrogel as active binding matrix in optical biosensors. In this study, we propose an extension of surface plasmon resonance (SPR) and optical waveguide mode (OWS) spectroscopy, for in situ observation of nano-patterned hydrogel film that are allowed to swell and collapse by varying the external temperature of the aqueous environment. Weak refractive index contrast of hydrogel structures arranged in periodic pattern, is generally associated with intrinsically low diffraction efficiency. In order to enhance the intensity of diffracted light, the surface is probed by resonantly excited optical waveguide modes, taking advantage of the fact that the hydrogel can serve as optical waveguide (HOW) enabling the excitation of additional modes besides surface plasmons. Thus, we provide a hydrogel optical waveguide-enhanced diffraction measurements, taking advantage of strong electromagnetic field intensity enhancements that amplifies the weak diffracted light intensity. The main part of the thesis is focused in the study of azopolymer-containing materials, a specific class of light-responsive materials. Upon photon absorption, azobenzene undergo reversible trans-cis photoisomerization, which induces a substantial geometrical change of its molecular structure, that can be translated into larger-scale movements of the material below the glass transition temperature (Tg) of the polymer. In Chapter III, by exploiting the light-induced mass migration phenomenon, we demonstrate that an azopolymeric film patterned by soft imprinting technique, can be anisotropically deformed and consequent restored in its initial shape via single irradiation just by controlling the polarization state of the incident laser beam. We also propose that the light-driven morphological manipulation can induce anisotropic wettability changes. Lastly, a polarization driven birefringence effect on flat and structured surfaces is discussed. Chapter IV focuses in the design of novel azopolymeric systems, where the optical response is provided by azobenzene molecules, which doped two different host materials. The photo-responsive behavior and potential applications of azo compounds incorporated into either a soft elastomeric and in rigid matrix is discussed. Azo-embedded poly(dimethylsiloxane) (PDMS) is studied as tunable optical lens and an azo-doped photocurable commercial polymeric resin is developed to study the photo-mechanical transduction of a 3D suspended membrane fabricated by two photon lithography technique. In Chapter V, we propose a light-deformable azopolymeric micro-pillars patterned substrate as a biocompatible and “smart” platform for dynamic material-cell observation in 2D environment, modified by a holographic optical conditioning. The aim is to observe by time-lapse acquisitions, how an in situ deformation of a pre-patterned structure can influence cell functions and fate. Finally, in Chapter VI, general remarks of the present work are discussed, and directions for future perspective are summarized.

Conventional inorganic materials for x-ray radiation sensors suffer from several drawbacks, including their inability to cover large curved areas, me- chanical sti ffness, lack of tissue-equivalence and toxicity. Semiconducting organic polymers represent an alternative and have been employed as di- rect photoconversion material in organic diodes. In contrast to inorganic detector materials, polymers allow low-cost and large area fabrication by sol- vent based methods. In addition their processing is compliant with fexible low-temperature substrates. Flexible and large-area detectors are needed for dosimetry in medical radiotherapy and security applications. The objective of my thesis is to achieve optimized organic polymer diodes for fexible, di- rect x-ray detectors. To this end polymer diodes based on two different semi- conducting polymers, polyvinylcarbazole (PVK) and poly(9,9-dioctyluorene) (PFO) have been fabricated. The diodes show state-of-the-art rectifying be- haviour and hole transport mobilities comparable to reference materials. In order to improve the X-ray stopping power, high-Z nanoparticle Bi2O3 or WO3 where added to realize a polymer-nanoparticle composite with opti- mized properities. X-ray detector characterization resulted in sensitivties of up to 14 uC/Gy/cm2 for PVK when diodes were operated in reverse. Addition of nanoparticles could further improve the performance and a maximum sensitivy of 19 uC/Gy/cm2 was obtained for the PFO diodes. Compared to the pure PFO diode this corresponds to a five-fold increase and thus highlights the potentiality of nanoparticles for polymer detector design. In- terestingly the pure polymer diodes showed an order of magnitude increase in sensitivity when operated in forward regime. The increase was attributed to a different detection mechanism based on the modulation of the diodes conductivity.

We have developed a new chemical methodology, based on simple acid-base hydrolysis of aminosilanes with molecules containing terminal OH groups, to prepare robust siloxane based polymers and organic-inorganic hybrid network materials for second-order nonlinear optics. First, a variety of polymers containing NLO-active chromophores covalently bound to the siloxane backbones, [-R2Si-(O-SiR2)n-O-(NLO-Chromophore)-O-] n (R = CH3 or CH3/C6H4) and [-R2Si-(O-SiR2)n-O-R'-O-(NLO-Chromophore)-O-] n. (R' = -C6H4-C 6H4-C6H4-), were prepared. Their solubility in common organic solvents, and high thermal stability, imparted ease of thin film preparation, and subsequent poling at high temperatures. These polymers exhibit good second-harmonic generation susceptibilities, and the temporal stabilities of the SHG signals were dependent on the polymer backbone and the molecular structures of the NLO chromophoms. A detailed analysis of their physical properties is reported. Then, a methodology of acid-base hydrolysis was used to produce copolymers containing dimethylsiloxane, imide linkages and NLO-active chromophores. These copolymers were soluble in polar solvents, and possessed high thermal stabilities and glass transition temperatures. Easily fabricated and poled thin films of these polymers exhibited good second-order nonlinear optical susceptibilities with long-term temporal stabilities of the second-harmonic generation signals at room temperature. Finally, an alternative approach, based on the same acid-base hydrolysis technique, to prepare organic-inorganic hybrid network material, was developed. In these hybrid materials, NLO-active chromophores such as Disperse Red 19, a pyridinium. salt based dye, and 1-amino-4-nitrobenzene, were covalently locked into silica networks. The hybrids were soluble, and offered ease of processibility in the preparation of good optical quality thin films. The network materials that are akin to the traditional sol-gel approach were also prepared

Polyvinylidene fluoride (PVDF) and its copolymer with trifluoethylene (PVDF-TrFE) have been widely investigated. This is largely attributed to their ferroelectric properties, which are present in a limited number of polymers. In comparison with the more widely used ferroelectric ceramics, the ease of their fabrication makes them attractive in flexible electronic devices. Despite many advances in their application, we are still lacking a complete fundamental understanding of the relationship between their structure and the functional properties. The melt-extrusion of PVDF revealed that the α-phase is predominantly formed in films. The ferroelectric β-phase PVDF was obtained by high temperature drawing of the α-phase of as-extruded films. It was observed that a minimum draw ratio of 3 is required to generate the β-phase. Chain mobility is crucial to the formation of β-phase. Too high chain mobility when drawing at temperatures above 100 °C can only orientate the pre-existing α-crystals without making the chain conformation change to form the β-crystals. Furthermore, the comparison between the produced α- and β-PVDF films is summarized. The α-PVDF films crystallized into spherulites with random orientation, while β-PVDF films displayed fibriliar structure showing preferred orientation of the polymer chains along the drawing direction. The overall crystallinity obtained from DSC data hardly varied, however, the drawn β-PVDF films had a lower melting temperature, which was also confirmed from the dielectric temperature spectra. The drawn β-PVDF films showed higher dielectric constant and larger remnant polarization compared with the as-extruded α-PVDF films, which is mainly ascribed to their higher β-phase content and preferred orientation. Highly aligned PVDF-TrFE films were processed using a melt extrusion processing route. Crystalline structure and orientation were optimized by controlling the melt extrusion conditions. XRD patterns suggested that there was nearly perfect alignment of the c-axis (polymer chain direction) along the extrusion direction in the optimized as-extruded films. SEM analysis confirmed the morphology of the crystalline phase, showing edge-on lamellae stacked perpendicular to the extrusion direction. DSC data indicated high crystallinity and well-ordered ferroelectric structure of the extruded films. FTIR spectroscopy revealed strong intermolecular dipole-dipole interaction in the extruded films. Accordingly, the optimized as-extruded PVDF-TrFE films exhibited a coercive field of 24 kV/mm, half of the commonly reported values for bulk films (~ 50 kV/mm) and a remnant polarization of 0.078 C/m2 which further increased to 0.099 C/m2 after annealing. This value is close to the theoretical limit (0.102 C/m2) assuming perfect in-plane c-axis orientation and 100% crystallinity. The typical limitations of PVDF - low crystallinity and indirect ferroelectric β-phase crystallization - and PVDF-TrFE - higher materials and processing costs and a low Curie point - are tackled by a simple and industrially viable melt blending approach. Despite the immiscible nature of PVDF and PVDF-TrFE, strong interactions exist between the two polymers when co-melt processed, which substantially affect the morphology and texture of the blends as well as their dielectric and ferroelectric properties. Surprisingly, minor amounts of PVDF-TrFE led to a significant increase in the β-phase content and preferred orientation of PVDF, well beyond the rule-of-mixtures. Moreover, the blends exhibited maximum increases in the dielectric constant of 80% and 30%, respectively compared with pure PVDF and PVDF-TrFE. The ferroelectric remnant polarization increased from 0.040 to 0.077 C/m2, while the coercive field decreased from 75 to 32 kV/mm with increasing PVDF-TrFE from 0 to 40 wt. %. The enhancement of properties is explained by the strong interactions at the interfaces between PVDF and PVDF-TrFE, which also suppresses the Curie transition of PVDF-TrFE, providing a potentially increased working temperature range for blended films, which is important in applications like non-volatile energy storage devices, ferroelectric field-effect transistors and touch sensors. Ferroelectric composites, integrating dielectric ceramic fillers with mechanically flexible polymers, are promising materials for flexible electronic applications. Numerous research works have demonstrated enhanced dielectric and ferroelectric properties of composite materials. However, the mechanisms responsible for these enhancements are not completely understood. Herein, PVDF and BaTiO3 (BTO) were used to study the effect of dielectric filler on the crystallization, phase transformation and dielectric properties of PVDF. The crystallization of α-PVDF was not affected by the presence of BTO particles, but small amounts of BTO (< 3 vol. %) made PVDF crystallize into larger spherulites. This is linked to crystallization kinetic studies, which showed that BTO acted as a nucleation agent for large full ring banded spherulites when its content was less than 1 vol. %. Furthermore, solid state drawing in the presence of BTO particles promoted the formation of β-PVDF with more pronounced crystalline orientation at high drawing temperatures (120 °C). The dielectric and ferroelectric properties were enhanced with BTO filling. The 100 °C oriented drawn PVDF tape exhibited a dielectric permittivity of 14 (100 Hz) and remnant polarization of 0.080 C/m2 (10 Hz), which increased to 20 and 0.095 C/m2, respectively, after filling with 5 vol. % BTO; neither resulting in high dielectric loss tangent (~ 0.02) nor obvious current leakage. Moreover, the coercive field decreased from 80 to 50 kV/mm with increasing BTO content from 0 to 5 vol. %.

Thesis (MSc)--Stellenbosch University, 2012.
ENGLISH ABSTRACT: In the modern, fast moving society of today, there is a strong focus in research placed on the elimination of lengthy invasive medical procedures. Target specific, and chemo selective treatments are of great interest. Various advantages of this include patient comfort and over and above all cost reduction of invasive procedures. This project focused on the development of an injectable gel system with the use of biocompatible polymers. A system is regarded as injectable if the functional polymers are in solution before administration, but gels when added together. In order to design this system, one has to make use of polymers with complimentary functional groups. Telechelic amino-functionalized PVP with narrow molecular weight distribution was synthesized via RAFT-mediated polymerization. The polymer was thoroughly characterized and cross-linked with Poly(styrene-alt-maleic anhydride) to form a three dimensional polymeric network capable of absorbing and retaining large amounts of water and or biological fluid. Unfortunately the cross-linking needed to be performed in non-aqueous solution due to hydrolysis of maleic anhydride as a competing reaction in water. The gel was used in two model studies. The first model study focused on the attachment of a synthetic polypeptide onto the gel. The second model study evaluated the cytotoxicity effects of these gels when placed in direct contact with rodent cardiac myoblast and myocyte cells. These studies rendered promising results for future biological applications.
AFRIKAANSE OPSOMMING: In die moderne, vinnig bewegende samelewing van vandag, word daar in navorsing, 'n sterk fokus geplaas op die uitskakeling van lang indringende mediese prosedures. Doel spesifieke, en chemo selektiewe behandelings is van groot belang. Verskeie voordele van hierdie is die toename in gemak van die pasiënt en die verlaging van kostes verbonde aan hierdie indringende prosedures. Hierdie projek het gefokus op die ontwikkeling van 'n inspuitbare gel stelsel deur gebruik te maak van biologiese aanvaarbare polimere. ‘n Stelsel word beskou as inspuitbaar, indien die funksionele polimere in oplossing is voor toediening, maar wel kan gel wanneer bymekaar gevoeg word. Om hierdie tipe stelsel te kan ontwerp moet daar gebruik gemaak word van polimere met beskikbare funksionele groepe. Telecheliese amino-funksionele Poly(N-vinielpirollideen) met 'n smal molekulêre gewig verspreiding is gesintetiseer deur middel van RAFT-bemiddelde polimerisasie. Die polimeer is deeglik gekarakteriseer en daarna gekruis-koppel met P(STY-alt-MAnh) om 'n driedimensionele polimeriese netwerk te vorm. Hierdie netwerk is dan ook in staat om groot hoeveelhede water en/of biologiese vloeistof te absorbeer en te behou. Ongelukkig was hierdie reaksie uitgevoer in ʼn nie-waterige oplossing as gevolg van die hidrolise van Maleïne anhydride as 'n mededingende reaksie in water. Die gel is in twee model studies gebruik. Die eerste model-studie het gefokus op die beslaglegging van 'n sintetiese polipeptied op die gel. Die tweede model studie het die sitotoksiese uitwerking van hierdie gels in direkte kontak met knaagdier hart myoblast en lymfocyten selle geëvalueer. Hierdie studies het dan ook belowende resultate vir toekomstige biologiese toepassings gelewer.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2007.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Vita.
Includes bibliographical references.
Conjugated polymers (CP)s display unique material properties that allow for implementation as sensors. For sensors to operate in complex biological environments, it is important to address the issues of sensitivity and specificity. To develop these attributes in a biosensor design, CPbased core-shell particles have been investigated as potential material platforms to detect protease activity. CP-based particles have greater sensitivity versus CPs in solution due to interchain and intrachain interactions afforded in the solid state. The CP core of the particle can be made using layer-by-layer assembly, a versatile technique that forms uniform polymeric films through non-covalent interactions. To measure the response of CP core particles in aqueous environments, a quantitative ratiometric approach was developed to account for system fluctuations encountered with particle dispersions. This method can help assess the molecular design of polymers and quenchers in a systematic approach. CP core particles, because of their electrostatic charge, suffer from nonspecific interactions with other charged species, and thus encapsulating CP particles with a hydrogel shell should create sensor materials with higher specificity.
(cont.) To illustrate this concept, CP-particle containing hydrogel films were created to permit selective interactions with designed quenchers. The encapsulation of the individual CPcore particles was accomplished through atom transfer radical polymerization (ATRP) of functional monomers from the surface, and the choice of reactive group on the monomer allows for bioconjugation on the particle shell. Future core-shell materials can also be developed with ATRP, and give prospects to new schemes for CP-based biosensing.
by Jessica Huien Liao.
Ph.D.

Polypyrrole (PPy) is a conjugated polymer that displays special electronic properties including conductivity. It may be electrogenerated with the incorporation of any anionic species including negatively charged biological molecules such as proteins and polysaccharides. For this thesis, variously loaded-PPy films were prepared on gold sputter-coated coverslips. The growth and characteristics of epithelial cells, namely keratinocytes, were studied on these films by microscopy, biochemical assay, immunocytochemistry and electrochemical impedance spectroscopy. Keratinocyte viability was found to be PPy-load dependent. For chloride, polyvinyl sulphate, dermatan sulphate and collagen-loaded PPy films, polycarbonate and gold, keratinocyte viability, as assessed by the AlamarBlueTM assay, was respectively 47%, 60%, 88% and 23%, 75% and 61% of tissue culture polystyrene controls after 5 days. This was found to require a previously unreported polymer washing step prior to cell seeding due to the observed toxicity of untreated films. Keratinocytes stained positive for proliferation (PCNA), suprabasal differentiation (K10) and hyperproliferation (K16) markers although cell morphology was poor for organotypical cultures on dermatanloaded PPy compared with de-epidermalised dermis. Cell-induced impedance changes were detected in a three-electrode format over PPy modified electrodes. Results obtained showed the effects of cell density, cell type and monitoring frequencies. In particular, it was seen that lower cell densities could be detected on PPy compared to unmodified gold electrodes. Keratinocyte confluence as determined by impedimetric analysis was reached more rapidly on PPy than bare gold in agreement with AlamarBlueTM measurements. Electrical equivalent circuit analysis using parameters whose contributions may be directly mapped to intracellular and intercellular spaces, and membrane components suggested that the technique can be extended to cell morphology discrimination. This work shows that PPy biocomposites are attractive candidates for tissue engineering applications since they may incorporate biomolecules and are electrically addressable with the potential to both direct and report on cell activities.

Polymers having one of the three complementary colors (red, green, and blue) in the reduced state and high transmissivity in the oxidized state are key materials towards use in electrochromic devices and displays. Although many neutral state red and blue polymers were reported up to date, neutral state green polymeric materials appear to be limited. For potential application of electrochromic materials in display technologies, one should have to create the entire color spectrum and this can be only achieved by having materials with additive or subtractive primary colors in their neutral states. To obtain a green color there should be at least two simultaneous absorption bands. Although the neutral state color is of great importance, the transmittance in the oxidized state is crucial too. The materials having one of the three primary colors should also possess highly transmissive oxidized states in order to be used in commercial electrochromic device applications. Donor-acceptor molecules lead to lower band gap due to resonances that enable a stronger double bond character between the donor and acceptor units. The materials with low band-gaps produce cathodically coloring polymers due to the lower energy transition in the doped state. Moreover, donor-acceptor type materials commonly show two absorption maxima. Since donor-acceptor approach seems to be the key to the complex nature of producing these materials, novel donor-acceptor type polymers were synthesized, and electrochromic properties were investigated in detail.Additionally a solution-processable donor-acceptor type polymer was realized using method of introducing alkyl side chains in the polymer structures.

Thesis (MSc)--Stellenbosch University, 2015.
ENGLISH ABSTRACT: The investigation of the barrier properties of highly filled polymer-clay hybrid latex films is described. Montmorillonite (MMT) clay contents ranging from 10–30 wt.% were effectively incorporated into polystyrene-butyl acrylate (PSBA) random copolymers, via miniemulsion polymerization. The optical properties of the films were evaluated using UV-Vis spectroscopy. Compared to the neat films, the PSBA nanocomposites retained remarkable visual properties. The light transmittance for PSBA films with styrene/n-butyl acrylate (S/BA) comonomer contents of 40:60 and 50:50 (mol.%) only decreased from 70% in the neat films to 50% in the nanocomposite films containing 30 wt.% clay. The best optical properties were observed in the films with S/BA comonomer contents of 30:70 (mol.%), the light transmittance only decreased from 85% (neat film) to 60% in the nanocomposite films containing 30 wt.% clay. The improved optical properties for the PSBA-30:70 films (compared to the PSBA-40:60 and PSBA-50:50 counterparts) were attributed to an increase in the low UV-absorbing butyl acrylate component of the copolymer, which at the same time has a low Tg that probably facilitated dispersion of the rigid MMT platelets in the matrix. In this study, the overall water vapour transport behaviour was governed by the MMT clay presence and less affected by the copolymer composition variation. The lower diffusion coefficients in the polymer clay nanocomposites (PCNs) were a result of the impermeable clay platelets which forced the water vapour molecules to follow longer and more tortuous paths to diffuse through the nanocomposite films. The irregular shape in the PSBA-40:60 and PSBA-30:70 neat latex particles was lost in the hybrid particles and well defined, dumb-bell shaped particles were observed. This was because of the faceting effect of the rigid MMT clay platelets. The MMT clay platelets were predominantly adhered to the surface of the PSBA latex particles because MMT clay particles have a larger size than the effective size of the copolymer particles. The stable overall transport coefficients in the PSBA-30:70-MMT films were attributed to the morphological organization of clay platelets in the matrix. The storage modulus of the materials decreased with an increase in clay content. This was attributed to the dual role played by the organoclay, firstly as nanofiller and reinforcing agent leading to the increase in storage modulus, and secondly as a plasticizer leading to a decrease of storage modulus.
AFRIKAANSE OPSOMMING: Die versperringseienskappe van hoogsgevulde polimeer-klei saamgestelde latekslae is beskryf. „n 10–30 wt % Montmorilloniet (MMT) klei inhoud is inkorporeer in polistireenbutielakrilaat (PSBA) onreëlmatige kopolimere, via miniemulsie polimerisasie. Die optiese eienskappe van die lae is bepaal m.b.v. UV-Vis spektroskopie. In vergelyking met die lae sonder klei (sogenaamde „neat films‟), het die PSBA nanosamestellings interressante visuele eienskappe getoon. Die ligtransmissie van die PSBA lae met „n stireeen/n-butielakrilaat (S/BA) komonomeerinhoud van 40:60 en 50:50 (mol %) het slegs afgeneem vanaf 70% in die „neat films‟ tot 50% in the nanosaamgestelde lae wat 30% klei bevat het. Die beste optiese eienskappe is waargeneem vir die lae wat „n 30:70 (mol %) S/BA komonomeerinhoud bevat het; die transmissie het slegs afgeneem vanaf 85% in die „neat films‟ to 60% in the nanosaamgestelde lae wat 30% klei bevat het. Die verbeterde optiese eienskappe van die PSBA-30:70 films (in vergelyking met die -40:60 and -50:50 films) is toegeskryf aan „n toename in die lae UV-absorberende butielakrilaat komponent van die kopolimeer. Terselfdetyd het laasgenoemde „n lae Tg-waarde, wat dispersie van die onbuigbare MMT kleiplaatjies in die matriks gefasiliteer het. In hierdie studie is die algehele waterdampvervoer deur die teenwoordigheid van die MMT klei beheer; dit is minder geaffekteer deur variasie in die samestelling van die kopolimeer. Die lae diffusiekoëffisiënte in die polimeer-klei nanosamestellings is as gevolg van die ondeurdringbare kleiplaatjies, wat die waterdampmolekules dwing om langs langer en meer gekronkelde paaie te diffundeer deur die nanosaamgestelde lae. Die onreëlmatige vorm wat gesien is in die PSBA-40:60 and PSBA-30:70 latekspartikels (sonder klei) het geleidelik verdwyn in die saamgestelde partikels, en goed-gedefineerde partikels met die vorm van handgewigte is waargeneem (in TEM beelde). Die rede hiervoor is die sogenaamde „faceting‟ effek, wat deur die onbuigbare MMT kleiplaatjies veroorsaak is. Die MMT kleiplaatjies sit hoofsaaklik aan die oppervlaktes van die PSBA latekspartikels. Die rede hiervoor is dat die MMT kleipartikels groter is as die effektiewe grootte van die kopolimeerpartikels. Die stabiele vervoerkoëffisiënte in die PSBA-30:70-MMT films is aan die unieke morfologiese eienskappe toegeskryf. Die bergingsmodulus van die materiale het monotonies afgeneem met „n toename in klei-inhoud. Dit is toegeskryf aan die tweedelige rol wat die organoklei speel – eerstens as 'n nanovuller en versterkingsmiddel, wat „n toename in bergingsmodulus tot gevolg het, en tweedens as „n plastiseerder, wat „n afname in bergingsmodulus tot gevolg het.

Nearly 60 m tonnes of waste is produced annually in Europe from “plastic packaging” engendering significant challenges for legislative controls and minimisation of environmental impact. There is an increasing demand for biodegradable packaging, which can be disposed of with minimum environmental impact, but the growing market is still in its infancy predominantly due to a lack of materials having environmental, practical and economic suitability. This research project dealt with some processing challenges of environmentally friendly packaging materials from renewable resources, as a long term solution to mitigate some issues associated with oil based plastic packaging. In this work, novel Polylactic acid (PLA) and starch based composites were developed with the requisite technical properties to fill the gap in the food packaging and cosmetic packaging industry. It was found that starch can be incorporated in a PLA matrix at the 10% level without difficulty in processing in the presence of 2% methyldiphenyl diisocyante. The blend shows properties similar to pure PLA. It was also found that the elongation at break and impact properties of PLA can be increased remarkably by the addition of a biostrength impact modifier. Furthermore, mixing of PLA and starch in the blend is efficient when the PLA particle size is reduced. It was also found that flexible and tougher PLA/starch blend pellets, that can be injection moulded, can be produced by an extrusion process with a range of additives. Each additive has a maximum level that exhibits optimum properties. The blends also established that 15% starch can be incorporated into the PLA matrix to reduce the cost without any processing difficulties. Encouragingly, the presence of an impact modifier in the PLA/starch blends has shown more desirable properties. Furthermore, the mechanical properties of the pellets exposed to increased residence time in the injection moulding barrel and of the test specimens stored for 9 months at 21ºC were also satisfactory for the new blend. The overall results exhibited some attractive properties in the tri blend system, which can be easily adopted by the plastics industry for development of an injection moulded product within the scope of applications such as dry food packaging or cosmetic packaging. A further finding of this project is that biodegradation under a home composting environment can be improved by incorporating starch and certain other modifiers into PLA.

Ce travail de thèse s’est inscrit au sein du projet européen Ecobinders dont l’objectif est le développement de nouveaux matériaux valorisant des produits dérivés de la biomasse tels que l’alcool furfurylique et/ou la lignine. De manière à comprendre les phénomènes physico-chimiques complexes mis en jeu lors des procédés d’élaboration et afin d’optimiser les propriétés de ces nouveaux matériaux, plusieurs approches originales ont été envisagées. Des études théoriques, comme l’analyse cinétique « sans modèle », u des techniques de pointe comme la calorimétrie multifréquence, la rhéométrie dynamique ont apporté un éclairage nouveau sur certains aspects fondamentaux. Lors de la polymérisation de l’alcool furfurylique, différentes étapes cinétiquement déterminantes ont mises en évidence et ont été attribuées soit à un contrôle par les mécanismes réactionnels ou à un contrôle par la diffusion. La polymérisation combinée alcool furfurylique / lignine a été étudiée et a permis l’élaboration de résines et de matrices thermodurcies. Les phénomènes de relaxation de la lignine ont été approfondis. Ceci a permis d’expliquer plus en détails le rôle de l’eau adsorbée, du vieillissement thermique et de mettre en évidence les aspects cinétiques. Enfin, des nano-hybrides ont été développés par deux voies distinctes. La voie sol-gel a été envisagée pour élaborer un nanocomposite alcool polyfurfurylique / silice qui a montré une amélioration de certaines propriétés mécaniques et thermiques. Un nouveau nano-composite argile / lignite / fibres naturelles a été développé par dispersion mécanique. Les propriétés barrières des feuillets d’argile ont amélioré la résistance thermique de ce matériau
This doctoral project has been conducted within the Ecobinders project which aims to develop new binders based on renewable resources such as furfuryl alcohol and/or lignin. Model-free kinetic and chemorheological analysis of furfuryl alcohol polymerisation have highlighted the different rate determing steps and the phase transitions (gelation, vitrification). The VOC’s released during polymerization have been identified. The influence of lignin incorporation on FA polymerization has been studied and oxidized or plasticized lignins have shown improved reactivity. Lab-scale polyfurfuryl alcohol or polyfurfuryl alcohol / lignin resins and thermoset have been elaborated on the basis of kinetic predictions. Evaluation of thermal instability, relaxation behaviour and morphological aspects of these lab-scale thermosets has highlighted a good compatibility between lignin and furanic network. Moreover, a polyfurfuryl alcohol / silica hybrid synthesized via sol-gel process has shown improved thermal performances as the consequence of nanoscales dispersion of silica particles. The quality control on new Ecobinders prototypes has been established. Dynamic aspects of lignin glass transition have been analyzed with multifrequency DSC together with other techniques. The influence of water sorption, thermal annealing, plasticization and fractionation has been considered. New layered silicate nanocomposite has been elaborated with lignin / natural fibres and improved thermal resistance has been shown

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

Comme je suis particulièrement intéressé par les nanosciences et les nombreuses applications des nanotechnologies, je me suis penché sur le développement de méthodes de fabrication de nanoparticules ultra-petites dont les fonctions peuvent être ajustées avec précision. Récemment, une nouvelle technologie appelée « technologie d’une seule chaîne », c’est-à-dire qui utilise une seule chaîne polymère, est devenue un sujet de recherche de plus en plus motivant pour la communauté scientifique. Cette technologie a l’avantage de dépendre d’une méthode facile de préparation de nanoparticules polymères d’une seule chaîne (SCNPs) et ayant des dimensions typiques de 1,5 à 20 nm. Leurs tailles ultra petites leur confèrent des propriétés spécifiques, ce qui permet de les utiliser comme capteurs, systèmes catalytiques, revêtements à faible viscosité, nanoréacteurs ou pour des applications biomédicales. Grâce aux contributions de nombreux scientifiques durant la dernière décennie, les méthodes de synthèse des SCNPs sont devenues très variées et représentent une technologie désormais mature. Néanmoins, de nombreux problèmes sont à résoudre dans ce domaine, ce qui permettra d’ajouter de nouvelles fonctions ou de les valoriser pour de nouvelles applications. Les polymères sensibles à plusieurs stimuli sont une classe de matériaux intelligents dont les propriétés peuvent être modifiées par l’application d’un stimulus extérieur. Ils sont utilisés extensivement dans les domaines énergétique et biomédical. Comme leurs propriétés physiques et chimiques peuvent être modifiées aisément et efficacement par un contrôle de leur environnement externe, ces polymères sont des candidats pour fabriquer de nouvelles SCNPs. Dans cette thèse, nous nous sommes intéressés au développement de SCNPs ayant de multiples fonctionnalités car cela permet d’ouvrir la voie pour de nouvelles applications. Pour cela, de nombreux polymères sensibles à plusieurs stimuli ont été préparés comme précurseurs à des SCNPs. En concevant spécifiquement ces polymères, il fut possible d’ajouter leurs propriétés de réponse à des stimuli dans les systèmes SCNPs. Le cœur même de cette thèse consiste en trois projets qui utilisèrent trois classes de SCNPs provenant de polymères sensibles aux stimuli. Grâce à leur réponse à plusieurs stimuli, ces SCNPs remplirent de nombreuses fonctions et subirent des modifications soit de leur structure, soit de leur morphologie, soit de leurs propriétés. Et en plus de la variété de fonctions, chaque classe de SCNPs a le potentiel pour de nombreuses applications. Dans la première étude présentée dans cette thèse (chapitre 1), nous avons préparé une classe de SCNPs photodégradables ayant une taille ajustable et inférieure à 10 nm. Il s’agit de polyesters rendus photosensibles par la présence de coumarines à l’intérieur de la chaîne principale (nommés CAPPG) grâce à la copolymérisation de coumarine diol, d’acide adipique et de propylène glycol (PPG). Cette incorporation de coumarines dans la chaîne principale permet au polymère d’être photosensible par deux façons. En effet, les coumarines peuvent se photo-dimériser, lorsqu’elles sont irradiées par des rayonnements UV (> 320 nm) en des cyclobutanes qui peuvent être ouverts à nouveau par d’autres rayonnements UV (254 nm) permettant la restauration des coumarines initiales. Cela a permis la création de SCNPs de tailles inférieures à 10 nm et incluant des propriétés de photodégradation. Cette propriété a été démontrée par une irradiation de 3 h avec des chaînes polymères de 13220 g/mol à 1385 g/mol dans les SCNPs. La taille de ces SNCPs (caractérisée par leur rayon hydrodynamique) peut être modifiée entre 3 nm et 5,3 nm en modifiant le taux de dimérisation des coumarines, ce qui est aisément obtenu en ajustant le temps d’irradiation UV. Les résultats ont démontré que cette méthode permet un contrôle aisé de la taille des SCNPs sans avoir recours à la synthèse de nombreux polymères précurseurs. Finalement, comme le polyester était biodégradable et biocompatible, ces SCNPs peuvent être exploitées pour des applications biomédicales. Dans la deuxième étude effectuée au cours de cette thèse (chapitre 2), nous avons préparé un nouveau type de SCNPs multifonctionnel à partir d’un polymère cristallin liquide. Il s’agit du polyméthacrylate de [2- (7-méthylcoumaryl) oxyéthyle - co - 6-[4-(4’-méthoxyphenylazo) phénoxy] hexyle] (PAzoMACMA). Les groupements latéraux du polymère contiennent, en majorité, des azobenzènes photoisomérisables et, en minorité, des coumarines photodimérisables. Les azobenzènes servent de mésogènes pour la formation de cristaux liquides alors que les coumarines ont été utilisées pour une réticulation photoinduite et intrachaîne. Malgré les dimensions inférieures à 15 nm, le confinement et la réticulation, les phases cristallines liquides (LC) persistèrent même dans les SCNPs. Ces SCNPs cristaux liquides (LC-SCNPs) présentèrent un certain nombre de propriétés intéressantes et particulières. Alors que leurs dispersions dans le THF n’étaient pas fluorescentes, celles dans le chloroforme l’étaient. En plus, ces nanoparticules s’aggloméraient quelque peu dans le chloroforme ce qui induisait des fluorescences différentes entre des SCNPs riches en isomères cis ou riches en isomères trans des azobenzènes. A cause de la photoisomérisation des azobenzènes, ces LC-SCNPs se déformaient sous irradiation comme le font les microparticules ou les colloïdes contenant des azobenzènes. Cependant, la déformation de ces nanoparticules dépend de la longueur d’onde de lumière polarisée. Alors que sous irradiation UV polarisée à 365 nm, l’élongation des SCNPs était perpendiculaire à la polarisation de la lumière incidente, sous irradiation visible polarisée entre 400 et 500 nm, l’étirement se faisait parallèlement à la polarisation. Finalement, un nanocomposite fut préparé par dispersion de LC-SCNPs dans une matrice de polyméthacrylate de méthyle (PMMA). Si celui-ci était étiré mécaniquement, les azobenzènes s’orientaient dans la direction de la déformation induite. Ces propriétés intéressantes des LC-SCNPs que cette étude a permis de dévoiler, suggèrent de nouvelles applications potentielles. Dans la troisième étude de cette thèse (chapitre 3), nous avons préparé une classe de SCNPs sensibles à la présence de CO2 et leurs agrégats micellaires auto-assemblés. D’un côté, des SCNPs ont été préparées à partir d’un polyméthacrylate de {(N, N-diméthylaminoéthyle)-co-4-méthyl-[7-(méthacryloyl)-oxyéthyl-oxy] coumaryle} (PDMAEMA-co-CMA). Lorsqu’elles sont dispersées en solution aqueuse, les nanoparticules individuelles peuvent subir des cycles réversibles d’expansion et de rétrécissement sous une stimulation alternative de CO2 et de N2 qui vont protoner et déprotoner les amines tertiaires. D’un autre côté, des SCNPs de type ‘Janus’ (SCJNPs) ont été préparées à partir d’un copolymère dibloc amphiphile : PS-b-P(DMAEMA-co-CMA) (PS correspond au polystyrène qui est hydrophobe). Ce type de SCJNPs peut s’autoassembler sous forme de micelles en solution aqueuse. Sous stimulation CO2 ou N2, l’expansion ou le rétrécissement à l’intérieur des particules permet de grands changements de volume. En plus, ces particules ont été étudiées comme potentiels nanoréacteurs pour des nanoparticules d’or (AuNPs) que ce soit sous formes SCNPs ou micelles SCJNPs. La vitesse de formation des AuNPs augmente sous bullage de CO2 et décroît sous N2. Cela permet de rendre possible cette réaction contrôlable par ces deux gaz. Qui plus est, utiliser des micelles de SCJNPs dont le volume peut être modifié sur un large intervalle en changeant l’intensité de la stimulation de CO2, permit d’obtenir des AuNPs de taille variable.
Abstract : With interests on nanoscience and nanotechnology for many applications, there is a demand for development of fabrication technology of ultra-small nano-size objects that allow for precise size control and tailored functionality. Recently, a new technology called ‘single-chain technology’, which manipulates a single polymer chain, becomes a rapidly-growing research topic. This technology provides a facile method to prepare polymer single-chain nanoparticles (SCNPs) with a typical size of 1.5-20 nm. Due to the ultra-small size-enabled unique properties, SCNPs have wide range of applications, including sensor, catalytic system, low viscosity coating, nanoreactor and biomedical applications. Through the contributions by many scientists in the past decade, the synthetic methodologies to fabricate SCNPs have been reported using various chemistries and been getting mature. However, there are still several unsolved problems in the field of SCNPs including functions and application. Stimuli-responsive polymers, as a class of smart materials whose properties can be changed by responding to external stimuli, have been widely used in energy and biomedical applications. Since their chemical and physical properties can be changed easily and efficiently via environmental control, stimuli-responsive polymers provide a potential pathway to preparing functional SCNPs. In this thesis, we are focusing on developing functional SCNPs, especially systems with multi-functions, and expanding their applications. To achieve this target, various stimuli-responsive polymers were prepared as polymer precursors and their stimuli-responsive properties were introduced into the SCNP systems by rational design of their chemical structures. The core of this thesis is comprised of three projects which deal with three classes of SCNPs from stimuli-responsive polymers. These stimuli-responsive SCNPs perform multi-functions and undergo certain change either in structure or morphology and properties. In addition, according to their variety of functions, each class of multi-functional SCNPs has diverse potential applications. In the first study presented in the thesis (Chapter 1), we prepared a class of sub-10 nm photodegradable and size-tunable SCNPs based on photo-responsive main-chain coumarin-based polyesters Poly{[7-(hydroxypropoxy)-4-(hydroxymethyl)coumarin adipate]-co- (polypropylene glycol adipate)} (CAPPG) through copolymerization of coumarin diol, adipic acid and polypropylene glycol (PPG). By incorporating coumarin moieties into the chain backbone of a polyester, dual photo-responsive reaction, i.e. photo-dimerization (>320 nm) and photo-induced chain scission (254 nm), occur under two different wavelengths of UV irradiation, enabling the preparation of sub-10 nm SCNPs and their photo-degradation property. The photo-degradability of SCNPs is evidenced under 254 nm UV irradiation for 3 h, which molecular weight of SCNPs decreasing from 13220 g/mol to 1385 g/mol. Moreover, the size of SCNPs can be tunable from 5.3 nm to 3 nm (hydrodynamic diameter) by varying the dimerization degree of coumarin moieties, that is simply controlled by the UV irradiation time. These results demonstrate a facile method to control the size of SCNPs without the need for synthesizing different polymer precursors. Finally, due to the biocompatible and biodegradable nature of polyester as polymer precursor, the SCNPs with photo-degradability and size-tunability have the potential to be exploited for biomedical applications. In the second study realized in this thesis (Chapter 2), we prepared a new type of multi-functional SCNPs from a side-chain liquid crystalline polymer (SCLCP), namely poly{6-[4-(4-methoxyphenylazo) phenoxy]hexylmethacrylate-co-4-methyl-[7-(methacr-yloyl) oxy-ethyl-oxy]coumarin} (PAzoMACMA). The polymer’s side groups comprise photo-isomerizable azobenzene in majority and photo-dimerizable coumarin in minority, with the former as mesogens and the latter for intra-chain photo-crosslinking. Despite the sub-15 nm size, confinement and crosslinking, the liquid crystalline (LC) phases of bulk PAzoMACMA persist in SCLCPs. Such LC-SCNPs exhibit a number of interesting and peculiar properties. While their dispersion in THF is non-fluorescent, when dispersed in chloroform, the nanoparticles appear to agglomerate to certain degree and display significant fluorescence that is different for SCNPs rich in the trans or cis isomer of azobenzene. The azobenzene LC-SCNPs also undergo photo-induced deformation, similar to azobenzene micro- or colloidal particles. However, the elongational deformation of the nanoparticles is dependent upon the linearly polarized excitation wavelength. While under polarized 365 nm UV irradiation the SCNP stretching direction is perpendicular to the light polarization, under polarized 400-500 nm visible light irradiation, the stretching takes place along the light polarization direction. Finally, an all-polymer nanocomposite was prepared by dispersing the LC-SCNPs in poly(methyl methacrylate) (PMMA), and mechanically stretching-induced orientation of azobenzene mesogens developed along the strain direction. The interesting properties of LC-SCNPs unveiled in this study suggest new possibilities for applications including bio-imaging and LC materials. As the third study in this thesis (Chapter 3), we studied a class of CO2-responsive SCNPs and their self-assembled micellar aggregates. On one hand, SCNPs are prepared from a random copolymer of poly{(N,N-dimethylaminoethyl methacrylate)-co-4-methyl-[7-(methacryloyl)oxyethyl-oxy]coumarin} (P(DMAEMA-co-CMA)). When dispersed in aqueous solution, individual nanoparticles can undergo reversible swelling/shrinking under alternating CO2/N2 stimulation as a result of the reversible protonation/deprotonation of tertiary amine groups. On the other hand, tadpole-like single-chain ‘Janus’ nanoparticles (SCJNPs) are prepared using an amphiphilic diblock copolymer of PS-b-P(DMAEMA-co-CMA) (PS is hydrophobic polystyrene). This type of SCJNPs can self-assemble into core-shell micellar aggregates in aqueous solution. Under CO2/N2 stimulation, the collective swelling/shrinking of SCJNPs within the micelle results in large, reversible volume change. In addition, both P(DMAEMA-co-CMA) SCNPs and PS-b-P(DMAEMA-co-CMA) SCJNP micelles are explored as gas-tunable nanoreactors for gold nanoparticles (AuNPs). The rate of AuNP formation increases under CO2 stimulation and decreases upon N2 bubbling, which makes it possible to tune the reaction rate up and down (on/off switching) by using the two gases. Moreover, using the micelles of SCJNPs, whose volume can be controlled over a wide range by adjusting the CO2 stimulation strength, variable-size AuNPs and their aggregates are obtained with continuous redshift of the surface plasmon resonance (SPR) into the long wavelength visible light region.