Dissertations / Theses on the topic 'Clay intercalation'

Wide angle X-ray Scattering (WAXS) measurements of the layered synthetic silicatesodium fluorohectorite (NaFh) when exposed to pressurized carbon dioxideare reported. With a custom made sample holder placed on top of a coolingsystem, measurements of the NaFh were taken at diferent conditions for temperatureand pressure. The interlamellar spacing of the clay particles is observedto expand approximately 2:4Å in the 001-direction when the sample is held at -20 degrees Celsius and exposed to 15 bar of CO2 for over 9 days, indicating the intercalation of CO2. The d-spacing after intercalation is indistinguishable from the d-spacing of NaFh in the 1WL hydration state. The rate of intercalation process is reported to be dependent on the temperature and the pressure of CO2, with the decreaseof temperature and the increase of pressure beeing favorable for intercalatingCO2. Through various measurements the possibillity of water as the observedintercalated guest substance has been ruled out. Molecular models based onthe swelling free energy are proposed to explain some of the features observedin the experiment.

Sepiolite is a clay mineral, a complex magnesium silicate, a typical formula for which is (OH2)4(OH)4Mg8Si12O30•8H2O. It is formed by blocks and cavities (tunnels) growing in the direction of the fibres. The tunnels, 3.7 x 10.6 Å in cross-section, are responsible for the high specific surface area and sorptive properties of sepiolite. The co-intercalation of 3-methyl cyclohex-2-en-1-one (MCH), the Douglas-Fir beetle anti-aggregation pheromone, with methanol, ethanol, acetone, or benzene into sepiolite tunnels was studied. The resulting nanohybrid materials were characterized by means of various techniques, such as multinuclear solid-state NMR spectroscopy, porosity studies and Thermal Gravimetric Analysis (TGA). This was done in the hope of obtaining slow and controlled release of MCH from the sepiolite tunnels. It was demonstrated by 13C MAS NMR (carbon-13 magic angle spinning nuclear magnetic resonance) that at room temperature there are two different MCH molecules: one MCH inside the tunnels and the other one outside the tunnels of the sepiolite. Heating nanohybrid materials at 60˚C for 20 hours removes the external MCH molecules from the sepiolite. 13C MAS NMR showed that by further heating nanohybrid materials at 120˚C for 20 hours, methanol, ethanol, or acetone peaks were greatly reduced; however, the benzene peak was not reduced. To better understand how benzene acts inside sepiolite, intercalation of d6-benzene, and co-intercalations of d6-benzene with MCH and d6-benzene with pyridine into sepiolite tunnels were carried out, and these samples were studied by the same techniques. Another technique was used in order to see whether the slow and controlled release of MCH from the sepiolite tunnels could be obtained: sepiolite-MCH nanohybrids were treated with 20 ml of 0.5 M HCl solution. It was found that when 1 gram of MCH-sepiolite sample was acid treated at room temperature, about 35% of intercalated MCH was removed from the sepiolite. The role of sepiolite clay was also studied in Maya-Blue representative structure sepiolite-indigo adduct. It is known that upon heating the sepiolite and indigo mixture, the stability that is present in Maya-Blue is achieved. It is still a mystery, however, how exactly indigo and sepiolite interact with each other.

The use of kaolinite for preparing functionalized materials for specialized applications is still a relatively niche research subject. This is in spite of its low cost, high availability, and the potential for covalently grafting organic functional groups to its inner and outer surfaces. These grafted compounds have been shown to be highly resistant to heat and solvents, making them very useful for certain applications, for example in polymer nanocomposite materials that require high thermal resistance during polymer processing. Solid state NMR has been shown to play an essential role in solving the structure of functionalized kaolinite materials, however the current knowledge base for these functionalized kaolinites is notably lacking for some nuclei such as 1H, 27Al and 17O. Research was undertaken to address these concerns by developing new synthetic strategies for preparing kaolinite based materials for use as nanocomposites and to examine commonly prepared modified kaolinite precursors materials by 1H and 27Al MAS NMR in an attempt to demonstrate their utility for characterizing kaolinite intercalated and grafted complexes. Solid state 1H NMR of a natural kaolinite, kGa-1b, identified two main proton signals attributed to inner and inner surface hydroxyl protons. The different affinity of these two types of hydroxyl groups towards exchange with deuterium was used to differentiate between the two. The 1H NMR spectra of a DMSO intercalated kaolinite, kDMSO, and a methanol grafted kaolinite, kmethoxy, were fitted with high accuracy using models consistent with the known structures of these materials. The 27Al MAS NMR spectra of a natural kaolinite, kGa-1b, a DMSO intercalated kaolinite, kDMSO, and a methanol grafted kaolinite, kmethoxy measured at 21.1T showed little difference between one another, while noticeable differences could be seen at 4.7T. 27Al MQMAS experiments found almost no difference between these materials in the multiple quantum dimension, suggesting the differences that were observed are a result of differences in quadrupolar parameters rather than chemical shifts. The 27Al NMR spectra of kGa-1b, kDMSO and kmethoxy were fitted with good accuracy using models consistent with known structures of these materials. Different Al(III) sites with CQ values varying by up to 0.6MHz were found. The 27Al NMR spectra of two different methanol grafted kaolinites were also compared and it was found that the intensities of the sites with lower values of CQ were dependent on the quantity of grafted aluminum sites. The interlayer space of kaolinite was functionalized with a block copolymer: poly(ethylene)-block-poly(ethylene glycol) using a kaolinite pre-intercalated with DMSO, kDMSO, and with a biodegradable polymer: poly(lactide) using a kaolinite pre-intercalated with urea, kurea, both by using melts of the polymer. The polymers were found to completely displace their precursors from the interlayer space giving a monolayer type arrangement of the polymer. Attempts were made to graft compounds containing polymerizable functional groups: 3-allyloxy-1,2-propanediol and ethylene glycol vinyl ether to kaolinite’s inner surfaces using a kaolinite pre-intercalated and grafted with methanol, kmethoxy, and a kaolinite pre-intercalated with DMSO, kDMSO, respectively. Both compounds were found to displace their precursors from the interlayer space, adopting a monolayer type arrangement. 13C and 29Si NMR results suggest 3-allyloxy-1,2-propanediol’s allyl group remains intact and partially keys into the clay mineral’s siloxane rings. Ethylene glycol vinyl ether was found to undergo intramolecular cyclization to form an acetal product, consuming its vinyl group in the process. This reaction was observed using an unmodified kaolinite, kGa-1b, suggesting that the clay mineral’s surfaces, both inner and outer, act as an acid catalyst.

This thesis is concerned with an experimental study of clay intercalation by organic dye molecule which is crucial for the successful development of a stable clay-dye pigment with combined advantages of organic dye and inorganic clay. Clay-dye pigments were prepared by two different methods. Two different organic dyes were used with unmodified clay and modified clay to study the intercalation. Characteristics of clay-dye pigment have been investigated using X-Ray Diffraction, Thermo-gravimetric Analysis and Transmission Electron Microscopy. In this thesis it is shown that the absorption of cationic dye by unmodified clay in aqueous medium mainly takes place in the interlayer clay surface. More likely the dye molecules with aromatic quaternary ammonium cation intercalate the clay layer and strongly interacts with the clay interlayer oxygen plane, where solvent dye (which is hydrophobic in nature) adsorption by unmodified clay mainly takes place on outer surface of the clay. Dye molecules are weakly interacted with outer surface oxygen plane by hydrogen bonding or Vander Waals forces. Modified clay enabled the solvent dye to intercalate inside the clay interlayer surface with the suitable non-aqueous medium (because of its expanded structure). The modified clay suspension in the selected non-aqueous medium shows only partial desorption of alkyl ammonium molecule from the clay layer with the presence of both cationic dye and solvent dye. Therefore the penetrated dye molecules must have weakly interacted with the interlayer oxygen plane as well as the remaining alkyl ammonium molecule present inside the clay layer. It is believed that the thermal and UV stability of organic dye can only be facilitated by a specific interaction (Ĉ-interactions) between aromatic alkyl ammonium cation of organic dye molecule and the interlayer oxygen plane of clay minerals. This interaction possibly enables the high thermal energy or the energy of the UV radiation to transmit immediately into the clay layer. Therefore organic dye molecules are protected from high energy loading and hence thermal and UV stability are improved.

The influence of low molecular weight additives containing polar groups and modified polyolefin-based compatibilisers on polypropylene (PP)-clay nanocomposites (PPCN) has been studied, in terms of intercalation and degree of exfoliation achievable by melt state mixing processes. PPCN were prepared by melt mixing of two commercial pp homopolymers with organically modified clay (OMMT) in the presence of maleic anhydride grafted pp (PP-MA). X-ray diffraction (XRD) analysis shows that the interlayer spacing of clay increases dramatically, whilst transmission electron microscopy (TEM) results show a significant improvement of clay dispersion in the PP matrix, when nanocomposites are prepared with commercial PP containing short chain organic additives with polar groups (amide-type slip and antistatic additives). Subsequent studies based upon customised PP formulations, with short chain amide molecules (AM), confirm the intercalation of this additive into clay galleries. The maximum interiayer spacing is achieved with low concentrations of this additive (0.5 wt. %). Contact angle measurements and low shear melt flow properties (MF!) further confirm the diffusion of this additive (AM) into the clay galleries rather than migrating away from the bulk of the PPCN. The interaction between the polar group (CONH2) of this additive and polar sites of the clay surface appears to be the driving force for the intercalation. Although this additive intercalates and allows the formation of an intercalated nanocomposite structure with non homogeneous dispersion of clay, an exfoliated PPCN structure is yet to be formed with this additive alone. A new preparation method for PPCN has therefore been developed by co-intercalation of AM and PP-MA. PPCN were prepared by this method with a significant reduction of overall PP-MA concentration in the nanocomposite structure, relative to conventional PPCN prepared with compatibiliser (PP-MA) only. XRD and TEM analysis showed that nanocomposite structures are formed with significantly improved clay dispersion, compared to PPCN prepared using the conventional method. Quantification of clay exfoliation, using image analysis software, showed that higher degrees of exfoliation can be achieved in PPCN from this new cointercalation method. Normalised melt flow index (n-MFI) data showed the relationship between low shear flow properties and clay structure and is an appropriate parameter to examine clay exfoliation and its interaction with pp in PPCN. Enhanced thennal stability of PPCN, in comparison to pure PP, further demonstrates the improved clay dispersion in nanocomposite structures prepared by the co-intercalation method. A possible mechanism for the co-intercalation of AM and PP-MA into clay galleries has been proposed, based upon hydrogen bonding between these additives and the silicate layers. Rheological characterisation of PPCN, using capillary rheometry experiments at high shear rates, shows a shear thinning, pseudoplastic behaviour similar to pure PP. However, a comparatively higher concentration of AM appears to reduce the shear viscosity of PPCN. Die swelling behaviour revealed a reduction in melt elasticity in PPCN melts in comparison to unmodified PP. Reduced die swell occurs as a result, together with a delay in the onset of melt fracture. Sheet extrusion was used to produce PPCN products with increasing clay loading levels that were evaluated for a range of mechanical properties. Significant enhancement of modulus in PPCN is achieved in comparison to pure PP whilst maintaining similar strength characteristics. However, impact resistance of extruded PPCN sheets is not improved in comparison to unmodified PP. Results have been interpreted with reference to the degree of exfoliation, additive content and differences in PP crystallinity.

Dissertation (Ph.D.)--University of Toledo, 2007.
Typescript. "Submitted as partial fulfillment of the requirements for The Doctor of Philosophy Degree in Engineering." Bibliography: leaves 200-205.

Cette thèse porte sur la relation entre le procédé de préparation et la structure des nanocomposites polypropylène/argile. Les échantillons ont été préparés au mélangeur interne dans un premier temps. Des observations au microscope électronique à balayage, complétées par des analyses en diffraction des rayons X ainsi que des mesures rhéologiques ont permis de caractériser l’état de dispersion de l’argile à différentes échelles au sein du matériau. Nous avons comparé trois argiles organophiles et montré que la compatibilité chimique entre l’argile et la matrice est un facteur primordial afin d’obtenir une bonne dispersion : la Cloisite 20 et la Dellite 67G montrent de bons états de dispersion à toutes les échelles au contraire de la Cloisite 30B. Nous avons ensuite mis en évidence l’influence de la vitesse de rotation ainsi que du temps de mélange sur l’état de dispersion de l’argile. Le seuil de percolation de l’argile dans le polypropylène a été déterminé. Le lien entre état de dispersion et cristallinité du polypropylène a également été étudié.Les échantillons ont ensuite été préparés par extrusion bivis. L’influence de la vitesse de rotation sur l’état de dispersion de l’argile a été mise en évidence, tout autant que la dégradation de la matrice aux plus fortes vitesses. L’évolution de l’état de dispersion le long de la vis a montré que si l’intercalation était rapidement atteinte sur la vis, l’exfoliation progressait linéairement avant de saturer sur les dernières zones. L’utilisation d’une température de régulation plus faible ou d’une matrice plus visqueuse n’ont pas permis d’améliorer l’état de dispersion de l’argile ni d’éviter la dégradation de la matrice. Enfin, l’utilisation du logiciel Ludovic© a permis de mieux appréhender les phénomènes thermomécaniques mis en jeu lors de l’extrusion, mais également d’optimiser le procédé
This PhD focuses on the relationship between the preparation process and the structure of polypropylene/clay nanocomposites. First, the samples were prepared via an internal mixer. Scanning electron microscopy observations, completed by X-ray diffraction analysis and rheology measurements enabled us to characterize the clay dispersion state in the nanocomposite at different scales. Three organoclays were compared. It was shown that the chemical compatibility between the clay and the matrix was essential to ensure a good dispersion: Cloisite 20 and Dellite 67G showed good dispersion states at all scales, whereas Cloisite 30B did not. The influence of rotor speed and mixing time on the clay dispersion state was shown. The percolation threshold of the clay was determined. The link between dispersion state and crystallinity was also studied.The samples were then prepared via a twin-screw extruder. The influence of screw speed on the clay dispersion state was demonstrated, as well as the matrix degradation at high screw speed. The evolution of the dispersion state along the screw profile showed that intercalation was reached early in the screw profile, whereas exfoliation evolved linearly until the last mixing elements. A lower barrel temperature, as well as a more viscous matrix did not improve the clay dispersion state, and did not prevent the matrix degradation. Finally, the Ludovic© software allowed us to apprehend the thermomechanical phenomena involved during extrusion, but also to optimize the process

Heavy metals are non-degradable and their persistence constitutes ecotoxicological ramifications. Their presence in wastewater is inhibitory to microbial digestion processes and can lead to biomagnification in the environment. Clay minerals have been widely studied as inexpensive sorbent materials of aqueous-phase contaminants. Particularly in the case of kaolinite, a non-swelling clay with a low cation-exchange capacity, chemically enhanced derivatives exposing its OH-rich interlayer space to interactions with its external environment are of exceptional interest. The objective of this study was to prepare a novel functionalised kaolinite with the aim of significantly improving its heavy-metal sorption capacity. Due to the robustness of sulfur-metal linkages, the compound 3,6-dithia-1,8-octanediol (HO(CH2)2S(CH2)2S(CH2)2OH) was grafted onto both urea- and DMSO precursors of two kaolinitic clays: the Source clay KGa-1b and a Portuguese clay sample collected from the Clays of Taveiro formation. All samples were characterised by X-ray diffraction and 13C nuclear magnetic resonance spectroscopy (NMR). Initial materials and final samples were also characterised by thermal gravimetric analysis and infrared spectroscopy. The results describe nanohybrid materials that are resistant to hydrolysis and exhibit different grafting fashions. Application as a heavy metal sorbent was tested in ZnCl2 solutions as well as in zinc-spiked raw wastewater. Zinc concentrations were analysed concomitant with other metal species by inductively coupled plasma – mass spectrometry, demonstrating variable sorption capacities of the different clay samples tested and a consistently greater zinc removal in the wastewater system compared to simple zinc solutions. Measured concentrations of concomitantly analysed metals reveals a potentially alarming release of certain heavy metal species from some clay samples as a result of zinc sorption.

The presence of clays in the sands used for concrete production interferes with the development of the fluidity of concrete, producing an instantaneous slump loss just after batching and the premature loss of fluidity. This interference occurs with all types of additives and clays but is especially problematic when combining sands containing expansive clays such as montmorillonites with new-generation high water-reducer/superplasticizer admixtures based on polycarboxylate polymers (PCE). Water-reducers based on PCE polymers offer much better performance than traditional superplasticizers based on sulfonated naphthalene polymers (BNS) and sulfonated melamine polymers (MNS), making great advances in concrete technology, both from the technical and economical point of view as in reducing the environmental impact associated to concrete. However, these advantages are inhibited when sands contain clays of the expansive type in their composition. All the preventive or corrective measures to mitigate the harmful effect of clays contained in sands result in increases of production costs and in greater environmental impact. For this reason, during the last years it has been tried to develop polymeric structures that offer the same benefits than polymers PCE but with improved tolerance against clays of the expansive type, such as montmorillonite clays, but without getting to reach solutions with guarantees of success, due to the complexity of the interaction process between PCE polymers and montmorillonite clays. This doctoral thesis aims to deepen knowledge about the mechanism of interaction between PCE polymers and montmorillonite clays, assuming that the deep understanding of the interaction mechanism is the essential previous step to finally develop high-performance, clay-insensitive superplasticizers for concrete. For this, the research is structured in three parts, motivated by the discrepancies that the current model of interaction proposed shows with the experimental results of sorption and fluidity loss. In the first part, it is intended to develop a test method that allows to observe the real expansion profiles of the clays in such a way that the mentioned discrepancies can be clarified. Secondly, with the proposed test method, it is intended to identify how the structure of PCE polymers, as well as the dosage used, influences on the expansion of montmorillonite clays produced by the absorption of polymer. And, thirdly, to identify how the properties of clay affect the interaction process. The first phase of the research campaign has made it possible to propose an improved test method for the d-spacing determination that revealed the real intercalation behavior, by which the number of PCE side chains intercalated into the interlaminar space of montmorillonite clays is up to ten times higher than that deducted from the traditional analytical method. And from the new test method proposed it has been possible to clarify the role of the different structures of PCE polymers and the properties of montmorillonite clays in the intercalation mechanism, in agreement with the experimental results of fluidity loss and of sorption behavior. Based on the mentioned achievements, an extended model for the intercalation mechanism has been proposed, whereby montmorillonite clays inhibit the dispersing capacity of PCE polymers, being able to identify the parts and properties of both the clay and the PCE polymers that control this process. With this contribution, the knowledge of the intercalation mechanism is extended to understand how the interaction between PCE polymers and montmorillonite clays is developed, which is the main objective of this research.
La presencia de arcillas en las arenas empleadas para producir hormigón interfiere en el desarrollo de la fluidez de los hormigones, produciendo una pérdida de cono instantánea tras el amasado y la pérdida prematura de fluidez. Esta interferencia se produce con todos los tipos de aditivos y de arcillas, pero es especialmente problemática cuando se combinan arenas que contienen arcillas expansivas del tipo montmorillonita con aditivos superplastificantes de nueva generación basados en polímeros de policarboxilato (PCE). Este tipo de aditivos superplastificantes basados en polímeros de PCE ofrecen prestaciones muy superiores a las de los superplastificantes tradicionales basados en polímeros de naftalensulfonatos (BNS) y melaminas sulfonadas (MNS), aportando grandes mejoras en la tecnología del hormigón, tanto desde el punto de vista técnico y económico como en la reducción del impacto ambiental asociado al hormigón. Sin embargo, estas ventajas quedan inhibidas cuando las arenas contienen arcillas del tipo expansivo en su composición. Todas las medidas preventivas o correctivas aplicadas para mitigar el efecto dañino de las arcillas contenidas en las arenas acarrean incrementos de coste de producción y mayor impacto ambiental. Por este motivo, durante los últimos años se ha intentado desarrollar estructuras poliméricas que ofrezcan las mismas prestaciones que los polímeros de PCE pero con mayor tolerancia frente a arcillas del tipo expansivo, como por ejemplo las montmorillonitas, pero sin llegar a alcanzar soluciones con garantías de éxito, debido a la complejidad del proceso de interacción entre los polímeros de PCE y las arcillas montmorillonitas. Esta tesis doctoral pretende profundizar en el conocimiento en torno al mecanismo de interacción entre los polímeros de PCE y las arcillas montmorillonita, entendiéndose que la comprensión del mecanismo de interacción es la etapa previa esencial para lograr, finalmente, desarrollar aditivos superplastificantes de altas prestaciones e insensibles a las arcillas. Para ello, la investigación se estructura en tres partes, motivado por las discrepancias que el actual modelo de interacción propuesto muestra con los resultados experimentales de sorción y de pérdida de fluidez. En primer lugar, se pretende desarrollar un método de ensayo que permita observar el perfil de expansión de la arcilla real de tal modo que las discrepancias mencionadas puedan ser clarificadas. En segundo lugar, con el método de ensayos propuesto, se pretende identificar como influye la estructura del polímero de PCE, así como su dosificación, en la expansión de la arcilla producida por la absorción de polímero. Y, en tercer lugar, identificar como influyen las propiedades de la arcilla en el proceso de interacción. La primera fase de investigación ha permitido proponer un método de ensayo para el factor de expansión d-spacing que vislumbra que el número de cadenas laterales del polímero de PCE intercaladas dentro del espacio interlaminar de las montmorillonitas es hasta más de diez veces superior al deducido con el método analítico tradicional. Y a partir del nuevo método de ensayo ha sido posible clarificar el rol de las diferentes estructuras de los polímeros de PCE y de las propiedades de la arcilla en el mecanismo de intercalación, en consonancia con los resultados de fluidez y de sorción. A partir de los logros mencionados, se ha propuesto un modelo extendido del mecanismo de intercalación por el cual las arcillas montmorillonitas inhiben el efecto dispersante de los polímeros de PCE, pudiendo identificar cuáles son las partes y propiedades tanto de la arcilla como de los polímeros de PCE que controlan este proceso. Con esta aportación, se amplía el conocimiento para comprender como se desarrolla la interacción entre los polímeros de PCE y las arcillas montmorillonitas, que es el objetivo principal de esta investigación.

This thesis focuses on the synthesis and characterisation of organoclays. X-ray diffraction has been used to study the changes in the basal spacings of montmorillonite clay and surfactant-intercalated organoclays. Variation in the d-spacing was found to be a step function of the surfactant concentration. Three different molecular environments for surfactant octadecyltrimethylammonium bromide (ODTMA) within the surface-modified montmorillonite are proposed upon the basis of their different decomposition temperatures. High-resolution thermogravimetric analysis (HRTG) shows that the thermal decomposition of montmorillonite modified with ODTMA takes place in four steps attributing to dehydration of adsorbed water, dehydration of water hydrating metal cations, loss of surfactant and the loss of OH units respectively. In addition, it has shown that the decomposition procedure of DODMA and TOMA modified clays are very different from that of ODTMA modified ones. The surfactant decomposition takes place in several steps in the DODMA and TOMA modified clays while for ODTMA modified clays, it shows only one step for the decomposition of surfactant. Also TG was proved to be a useful tool to estimate the amount of surfactant within the organoclays. A model is proposed in which, up to 0.4 CEC, a surfactant monolayer is formed between the montmorillonite clay layers; up to 0.8 CEC, a lateral-bilayer arrangement is formed; and above 1.5 CEC, a pseudotrimolecular layer is formed, with excess surfactant adsorbed on the clay surface. While for dimethyldioctadecylammonium bromide (DODMA) and trioctadecylmethylammonium bromide (TOMA) modified clays, since the larger sizes of the surfactants, some layers of montmorillonite are kept unaltered because of steric effects. The configurations of surfactant within these organoclays usually take paraffin type layers. Thermal analysis also provides an indication of the thermal stability of the organoclay as shown by different starting decomposition temperatures. FTIR was used as a guide to determine the phase state of the organoclay interlayers as determined from the CH asymmetric stretching vibration of the surfactants to provide more information on surfactant configurations. It was used to study the changes in the spectra of the surfactant ODTMA upon intercalation into a sodium montmorillonite. Surfaces of montmorillonites were modified using ultrasonic and hydrothermal methods through the intercalation and adsorption of the cationic surfactant ODTMA. Changes in the surfaces and structure were characterized using electron microscopy. The ultrasonic preparation method results in a higher surfactant concentration within the montmorillonite interlayer when compared with that from the hydrothermal method. Both XRD patterns and TEM images demonstrate that SWy-2-Namontmorillonite contains superlayers. TEM images of organoclays prepared at high surfactant concentrations show alternate basal spacings between neighboring layers. SEM images show that modification with surfactant will reduce the clay particle aggregation. Organoclays prepared at low surfactant concentration display curved flakes, whereas they become flat with increasing intercalated surfactant. Fundamentally this thesis has increased the knowledge base of the structural and morphological properties of organo-montmorillonite clays. The configurations of surfactant in the organoclays have been further investigated and three different molecular environments for surfactant ODTMA within the surface-modified montmorillonite are proposed upon the basis of their different decomposition temperatures. Changes in the spectra of the surfactant upon intercalation into clay have been investigated in details. Novel surfactant-modified montmorillonite results in the formation of new nanophases with the potential for the removal of organic contaminants from aqueous media and for the removal of hydrocarbon spills on roads.

O presente trabalho de Doutorado tem como objetivo investigar a influência de materiais lamelares prístinos e modificados e a influência de diferentes rotas sintéticas nas propriedades físico-químicas do amido termoplástico, utilizando glicerol como plastificante. Para tanto, empregou-se para a produção dos materiais híbridos uma argila sintética da família das hectoritas (Laponita RD) na forma prístina e também modificada com íons berberine e carnosina, além de um hidróxido duplo lamelar (HDL) constituído por íons Zn2+/Al3+ intercalado com carboximetilcelulose (CMC). O amido e o material lamelar foram combinados, utilizando as metodologias de casting e extrusão, nas concentrações de 2,5 e 5,0 % (m/m) de argila ou HDL com relação ao polissacarídeo. Já quantidade de plastificante empregada foi variável, dependendo da rota de preparação empregada, sendo de aproximadamente 20 % (m/m) via casting e 30 % (m/m) via extrusão com relação ao amido. Conforme mostram os difratogramas de raios X dos filmes obtidos pelo método casting, todos os filmes contendo argila em sua composição exibem um sinal largo de difração na região de baixo ângulo de 2θ, embora pouco intenso, indica a existência de certa quantidade de nanocompósito do tipo intercalado. Já para os materiais obtidos via extrusão, os sinais de difração em baixo ângulo são consideravelmente alargados e muito pouco intensos. A propriedade térmica do amido termoplástico foi piorada em todos os casos estudados nos materiais contendo argila ou HDL em sua composição. A presença de carga inorgânica na formulação dos materiais híbridos preparados não retardou o processo de decomposição não-oxidativo do amido. A presença de uma maior quantidade de glicerol nos materiais obtidos por extrusão resultou em uma antecipação ainda maior no principal evento de perda de massa, em comparação com os mesmos materiais obtidos via casting. Devido à alta característica hidrofílica do amido, materiais lamelares intercalados com espécies que possuem maior caráter hidrofílico, como a Laponita prístina (contendo apenas íons Na+) e a carnosina mostraram uma melhor dispersão pela matriz polimérica, através da análise por técnicas de microscopia. Adicionalmente, observou-se uma melhor homogeneidade de distribuição da fase lamelar na fase polimérica nos filmes obtidos por casting em comparação com os materiais obtidos por extrusão. Os resultados mecânicos de todos os materiais híbridos analisados mostram tendências pouco conclusivas com relação ao amido termoplástico. Em geral, observa-se uma melhora muito sutil na máxima resistência a tração com a presença de material lamelar na composição dos materiais testados, além de uma diminuição na elongação máxima. Da mesma forma, a permeabilidade a gases dos filmes contendo argila ou HDL em sua composição mostrou resultados pouco conclusivos com relação ao amido termoplástico, geralmente exibindo uma redução modesta na permeabilidade. A investigação do perfil de biodegradação dos materiais contendo fase lamelar em sua composição mostrou que apenas a amostra contendo Laponita modificada com carnosina obtida por extrusão foi capaz de retardar significativamente a conversão do carbono das cadeias poliméricas em CO2, com relação ao amido termoplástico.
This present Thesis aimed to investigate the influence of pristine and modified layered materials and the influence of different preparation routes on the physicochemical properties of thermoplastic starch, using glycerol as plasticizer. To reach this goal, it was used to produce hybrid materials a synthetic clay belonging to the hectorite family (Laponite RD) in both pristine form and modified with berberine and carnosine ions and also a layered double hydroxide (LDH) comprised of Zn2+/Al3+ ions intercalated with carboxymethylcellulose (CMC). Both starch and the layered material were combined using casting and extrusion methodologies, using concentrations of 2.5 and 5.0 % (w/w) of clay or LDH relative to starch. The amount of plasticizer utilized was variable, depending on the preparation route employed. It was used approximately 20 % (w/w) of glycerol on casting route and 30 % (w/w) on extrusion route relative to starch. According to X ray diffractograms of the films obtained by casting route, all hybrid films that contain clay in their composition exhibit a large diffraction signal at low 2θ angle values, albeit its low intensity, indicates the existence of a certain contribuition of a intercalated nanocomposite. On the other hand, the hybrid materials obtained through extrusion method, these low angle diffraction signals are very broad and possess very low intensity. The thermal properties of thermoplastic starch were worsened in all studied cases after combined with clay or LDH. The presence of inorganic filler on the formulation of hybrid materials does not postpone the beginning of the non-oxidative decomposition process of starch. A higher amount of glycerol on the final materials obtained through extrusion resulted in an even greater anticipation on the main mass loss event in comparison to the analogous materials obtained using casting technique. Due to the high hydrophilic nature of starch, layered materials intercalated with ionic species that show higher hydrophilicity such as pristine Laponite (containing solely Na+ ions) and carnosine exhibited better dispersion through the polymer matrix, after being analyzed with microscopic techniques. Additionaly, it was observed a higher homogeneity of distribution of the layered phase over the polymer phase on the films obtained through casting in comparison to the materials obtained through extrusion. The tensile tests of all analyzed hybrid materials show a poorly conclusive trend in comparison to thermoplastic starch. In general, it was observed a subtle improvement on the maximum tensile strength of the materials containing layered material in their composition and also a decrease in the maximum elongation. In a same trend, gas permeability of the films was poorly conclusive in comparison to thermoplastic starch, generally resulting in a subtle reduction of permeability values. The investigation of biodegradation profile of the materials containing inorganic filler show that only Laponite modified with carnosine ions was able to postpone significatively the conversion of carbon from the polymer chains to CO2 in comparison to thermoplastic starch.

O presente trabalho tem como objetivo a síntese e caracterização de hidróxido duplo lamelar (HDL) do tipo hidrotalcita intercalado com metaloftalocianinas (CuPcTs e CoPcTs) e metaloporfirina (CoTPhsP) aniônicas. Como rota sintética, três métodos foram testados: (i) coprecipitação do hidróxido duplo em solução contendo o macrociclo; (ií) reconstituição estrutural da mistura de óxidos obtida pela decomposição térmica de HDL na forma carbonato e (ííi) decomposição térmica do carbonato intercalado empregando um meio contendo poliol. A influência do método de intercalação nas propriedades texturais do material e o efeito da imobilização dos macrociclos na região interlamelar foram avaliados através da caracterização textural (difração de raios-X e medidas de área superficial), espectroscópica (vibracional no infravermelho, eletrônica no UV/visível e ressonância paramagnética eletrônica) e das análises elementar (C, H, N e metais) e termogravimétrica. Avaliou-se a influência das propriedades texturais dos compósitos e do arranjo dos intercalados na reatividade e estabilidade dos macrociclos confinados no espaço interlamelar através da reação de decomposição do peróxido de hidrogênio. A síntese por coprecipitação dos hidróxidos duplos lamelares do tipo hidrotalcita mostrou-se eficiente para a obtenção de produtos puros e de alta cristal inidade. Entretanto, os materiais obtidos a partir da intercalação dos macrociclos nas matrizes de HDL através dos diferentes métodos sintéticos resultaram em sólidos com baixa cristalinidade. Os estudos mostraram que a obtenção de materiais contendo apenas uma fase é dependente do método de intercalação empregado. Os resultados de análise elementar indicaram um alto grau de intercalação dos macrociclos nos HDLs. Os espectros vibracionais no infravermelho apresentaram bandas que podem ser atribuídas à presença de íons carbonato no espaço interlamelar dos sistemas HDL-macrociclos. A incorporação completa do macrociclo foi observada para a CoPcTs intercalada no HDL via método da coprecipitação. Por outro lado, o método do poliol, utilizado para a intercalação da CuPcTs e CoPcTs, resultou em materiais com baixo grau de intercalação. A intercalação dos macrociclos nos HDLs foi confirmada através dos resultados obtidos por difração de raios-X, que indicaram um aumento substancial do espaçamento basal, que aumentou de aproximadamente 8A nas matrizes precursoras contendo CO32- para cerca de 23A nas matrizes contendo os macrociclos intercalados. As medidas de área superficial sugerem que não houve a formação de microporos nos HDLs incorporados com os macrociclos, pois estes não apresentaram valores de área superficial significativamente maior que os das matrizes de HDL na forma carbonato. A intercalação da CoPcTs e da CoTPhsP aumenta tanto a estabilidade térmica dos HDLs em relação à matriz com carbonato, quanto a dos próprios macrociclos. Em relação aos HDLs contendo a CuPcTs, observou-se comportamento térmico distinto. A intercalação da CuPcTs também aumenta a estabilidade térmica do HDL mas o confinamento do macrociclo provoca a sua decomposição em temperatura menor que aquela observada quando livre. Os espectros de absorção eletrônica mostraram que as metaloftalocianinas quando intercaladas nos HDLs apresentaram menor grau de agregação às espécies livres. Porém, os espectros de RPE indicaram que as espécies CuPcTs agregados são dominantes nas amostras intercaladas uma vez que apresentam apenas valor de g isotrópico (g=2,06). Os sistemas com a CoPcTs também apresentaram agregados mas em menor extensão que aqueles com os análogos de Cu(II). Com relação ao comportamento catalítico dos diferentes materiais sintetizados na decomposição do peróxido de hidrogênio, os três macrociclos estudados apresentaram comportamentos distintos. A CuPcTs suportada e intercalada no HDL não apresenta atividade catalásica embora a forma livre promova a dismutação do H2O2. Os materiais com a CoPcTs e CoTPhsP são mais ativos que o macrociclo livre na decomposição do peróxido de hidrogênio. Os HDLs com a CoTPhsP são mais resistentes ao ataque oxidativo do peróxido de hidrogênio que a porfirina livre. As ftalocianinas metaladas em meio homogêneo ou heterogêneo não são degradadas pelo H202. Preparation and characterization of layered double hydroxides intercalated with macrocyclic metallated species
The aim of the present work is to synthesize and characterize layered double hydroxides (hydrotalcite-like compounds) intercalated with anionic metallophthalocyanines (CuPcTs and CoPcTs) and metalloporphyrin (CoTPhsP). Three preparative methods were tested to isolate the intercalated materiais: (i) double hydroxide coprecipitation in the presence of the macrocycle, (ii) structure reconstruction of the mixed oxides obtained by thermal decomposition of layered double hydroxide (LDH) phase containing volatile ion; (iii) thermal decomposition of carbonate-containing phase in a polyol media. The influence of the intercalation method in the material textural properties and the effect of the macrocycle immobilization in the interlayer region were evaluate through the textural characterization (x-ray diffraction analysis and surface area measurements), vibrational (IR) and electronic (UV-visible) spectroscopy, elementary analysis and thermogravimetry. The effect of the composites textural properties and the intercalated species arrangement in the LDH gallery was evaluate carrying out the hydrogen peroxide decomposition reaction. The LDHs preparation by coprecipitation was an efficient method to obtain pure and crystalline products. However the macrocycle intercalated materiais isolated by the three methods mentioned above were poorly crystallized phases. The experimental data also showed that the isolation of materiais containing only one phase depends on the synthetic approach. The extension of intercalated macrocycle species in LDHs was broad as judged by elementary analysis data. The IR vibrational spectra showed some bands that can be attributed to the presence of carbonate ions in the interlayer of LDH macrocycle systems. Material containing approximately 100% of macrocycle in the LDH gallery was isolated by the double hydroxide coprecipitation in a solution containing CoPcTs. On the other hand, polyol method rendered materiais with small amount of intercalated metallophthalocyanines. The macrocycle intercalation between LDHs layers was confirmed by the x-ray diffraction patterns: the basal spacing of the carbonate precursor (ca. 8A) increases to approximately 23A in the matrices intercalated with phthalocyanines or porphyrin. The surface area data suggested that the macrocycle intercalated solids do not have microporous owing to the fact that as the surface area values are not higher than that obtained for the LDH precursor. CoPcTs and CoTPhsP intercalation increases the thermal stability of HDLs in relation to the carbonate phase as much as the macrocycle stability. CuPcTs systems showed a particular behaviour: the thermal stability of LDH structure is increased but the phthalocyanine decomposition occurs in a lower temperature than that observed to the macrocycle free form. The electronic absorption spectra revealed a decrease in the metallophthalocyanine aggregation when the species are intercalated in LDHs However the EPR spectra showed only the isotropic g value (g=2.07) evidencing that the CuPcTs aggregated species are dominant in the LDH samples. CoPcTs systems are also aggregated but in a less extension than the Cu(lI) compound. The catalase-like activity of the intercalated materiais was distinct for each macrocycle system tested. CuPcTs intercalated or supported in LDHs is not active in the hydrogen peroxide dismutation in despite of the free form shows activity. CoPcTs and CoTPhsP materiais exhibit better catalytic performance than the free macrocycles. LDHs containing CoTPsP are more resistant to the oxidative attack of hydrogen peroxide than the free porphyrin. Metallophthalocyanines species in homogeneous or heterogeneous media are not degraded by H202.

O presente trabalho trata da preparação e da caracterização de sistemas contendo tetrassulfoftalocianinas de Co(II) (CoPcTs) e Fe(III) (FePcTs) intercaladas ou somente adsorvidas externamente em matrizes de hidróxidos duplos lamelares (HDLs). Foram sintetizados materiais com composições variadas e empregando-se diferentes métodos de síntese visando, principalmente, o isolamento de materiais com microporosidade intracristalina e/ou com um baixo grau de agregação da ftalocianina. Técnicas de caracterização textural (difração de raios-X e medidas de área superficial) e espectroscópicas (vibracional na região do infravermelho, eletrônica no UV/visível, ressonância paramagnética eletrônica e absorção de raios-X), além das análises elementar (C, H, N e metais) e termogravimétrica foram utilizadas para a caracterização dos sólidos sintetizados. Avaliaram-se os materiais como catalisadores na reação de oxidação do 2,6-di-terc-butilfenol e do catecol, utilizando O2ou H2O2 como oxidantes. Nos materiais isolados contendo a CoPcTs intercalada em HDLs com composição MgxAl (x = 2, 3 e 4) e ZnxAl (x = 4 e 5), a ftalocianina está orientada perpendicularmente às lamelas do HDL, independentemente do método de síntese e da composição dos HDLs utilizados. Adicionalmente, constatou-se que a CoPcTs intercalada está altamente agregada e que os materiais não possuem microporosidade. Porém, a diminuição da densidade de carga do HDL provoca uma pequena diminuição na agregação da CoPcTs. Sob determinada condição sintética, a CoPcTs intercalada nos HDLs ZnxAl sofre o processo de enxertia através dos grupos sulfônicos. Quando testados como catalisadores na oxidação do 2,6-di-terc-butilfenol, os materiais contendo a CoPcTs intercalada e enxertada apresentaram reatividade inexpressiva, que pode ser devida ao acesso restrito do substrato ao sítio ativo na região interlamelar. Estudos de adsorção da FePcTs em HDLs MgxAl na forma carbonato, investigados por espectroscopia eletrônica UV/Visível in situ, mostraram uma elevada tendência de agregação da ftalocianina na superfície dos HDLs. Os espectros eletrônicos indicaram também que diferentes espécies derivadas da FePcTs são formadas durante o processo de adsorção nos HDLs e que a densidade de carga influencia o tipo de espécie adsorvida: há predominância de um dímero do tipo µ-oxo nos HDLs Mg2Al e Mg3Al e do dímero (FePcTs)2 no HDL Mg4Al. Os espectros de absorção de raios-X (XANES) da FePcTs adsorvida nos HDLs MgxAl mostraram que as espécies adsorvidas apresentam geometria piramidal de base quadrada (C4v) e/ou octaédrica (Oh), corroborando com os dados de espectroscopia no UV/Visível. Já os espectros de ressonância paramagnética eletrônica mostraram que a ftalocianina de Fe(III) quando adsorvida nos HDLs gera uma mistura de espécies com configuração de baixo spin e alto spin e, também, elevada distorção rômbica. A FePcTs adsorvida nos HDLs MgxAl apresentou estabilidade e reatividade catalítica superior quando comparada com a ftalocianina livre na oxidação dos fenóis. A ftalocianina adsorvida na superfície externa do HDL deve favorecer o acesso do substrato ao sítio ativo. Uma correlação entre os estudos de adsorção e os resultados dos testes catalíticos mostrou que a espécie dimérica do tipo µ-oxo pode ser a espécie mais ativa na oxidação dos fenóis. Nestes sistemas, as camadas positivas do HDL devem provocar um enfraquecimento da ligação O-H do fenol, facilitando a sua desprotonação (uma das etapas do mecanismo de oxidação). Este último efeito pareceu atuante, pois foram observadas reatividades crescentes dos catalisadores à medida que se aumentava a densidade de carga do HDL. Estes resultados indicaram que existe um efeito cooperativo nos HDLs MgxAl contendo a FePcTs adsorvida, mostrando que o HDL não atua como um suporte inerte nos processos estudados.
The present work describes the preparation and characterization of materials containing Co(II) and Fe(III) tetrasulfonated phthalocyanines (CoPcTs and FePcTs, respectively) intercalated or adsorbed on layered double hydroxides (LDHs). Different compositions and synthetic methods were used to isolate materials with microporosity and/or the phthalocyanine in a low aggregation degree. X-ray diffraction analysis, surface area measurements, spectroscopic techniques (infrared, UV/visible and X-ray absorption), elemental analysis and thermogravimetry were used to characterize the solids. The materials were tested as catalysts in the 2,6-di-terc-butilfenol and catechol oxidation, using O2 or H2O2 as oxidants. In the materials prepared by intercalation of the CoPcTs in MgxAl (x = 2, 3 and 4) and ZnxAl (x = 4 and 5) LDHs, the phthalocyanine is perpendicularly orientated related to the LDH layers, regardless of synthetic method or LDH composition used. In addition, it was observed that the intercalated phthalocyanine is aggregated and the solids do not have microporous. However, the aggregation degree of the phthalocyanine is slightly lower when the LDH charge density decreases. Under a particular synthetic conditions the CoPcTs intercalated in the LDH ZnxAl is grafted through the sulfonic groups. Catalytic tests uisng this material in the 2,6-di-terc-butilfenol oxidation showed a neglectful reactivity, which confirms the aggregation of the intercalated CoPcTs, thus avoiding that the substrate accesses the reactive center. In an adsorption study carried by monitoring in situ the FePcTs UV/Vis electronic spectra during its addition to LDH suspensions, a strong tendency of aggregation was observed for the FePcTs. In addition, different FePcTs species are formed during the adsorption process on the LDHs, which is influenced by the LDH charge density: the µ-oxo complex is the main species adsorbed on the Mg2Al and Mg3Al LDHs, whereas for Mg4Al the non oxo-bridged dimeric complex prevailed. X-ray absorption spectra (XANES) of the adsorbed FePcTs on the MgxAl LDHs showed that the species present a square-pyramidal (C4v) and/or an octahedral (Oh) symmetry, in agreement with the UV/visible spectroscopic data. EPR spectra of these samples showed that the FePcTs adsorbed on the LDHs leads to a mixture of Fe(III) high and low spin species along with a strong rhombic distortion. The FePcTs adsorbed on the MgxAl LDHs showed an enhanced catalytic activity and longevity in the phenols oxidation compared to the homogeneous counterpart. The phthalocyanine on the LDH external surfaces allows the access of the substrate to the reactive metal center. A correlation between the adsorption study and the catalytic tests pointed that the FePcTs µ-oxo complex may be the active species in the oxidation of phenols. Furthermore, the positive charge of LDH layers may weaken the O-H bonding in the phenol molecules making them more easily ionized (one step of the phenol oxidation mechanism). This feature seems to be effective because higher activities of the catalysts were observed along with increasing charge density of the LDHs. These results indicated that a cooperative effect takes place in the materials containing the FePcTs adsorbed on the MgxAl LDHs, showing that LDH do not act as an inert support in the studied catalytic reactions.

碩士
國立臺灣科技大學
高分子工程系
91
In this study , we use intercalation method to prepare polyimide/clay nanocomposites .And produce polyimide to compare with it .The characterization of polycodensation was investigated by FTIR spectroscopy and TGA .The surface of the clays was observed by SEM . The microstructure and morphology was identified with X-ray diffraction (XRD) and transmission electron microscopy (TEM) ,while thermal gravimetric analysis (TGA) and differential scanning calorimeter (DSC) were performed to demonstrate the thermal stability of the composites. SEM photos show that surface of clays were layer structure. XRD results indicate that distance of organoclays from layer to layer was really increased. And FTIR result shows polycodensation was processed during the synthesis of polyimide.In microstructures , TEM pohtos show polyimide/clay nanocompsites with C12Cl were intercalated nano- -compsites.In the thermal properties ,TGA results indicate that decomposed temperature Td of nanocompsites with C12Cl modify clay is worse than polyimide .When the weight percent of organoclays is increased ,the Td is also decreased .

碩士
國立臺北科技大學
有機高分子研究所
94
In this study, the EPDM/organic clay nanocomposites were prepared by melt intercalation. The effects of nanoclay in these EPDM/clay nanocomposites were investigated on their structures, mechanical, thermal and electrical properties. The structures of nanoclay in these EPDM/clay nanocomposites were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The mechanical and thermal properties were measured by Universal Tensile Testing Machine and Thermogravimentric Analyzer (TGA). The glass transition temperature was measured using Dynamic Mechanical Analyzer (DMA). The volume resistivity were measured by resistivity test meter. The nanocomposites exhibited great improvements in the tensile strength, elongation, and tensile modulus. The silicate layers of the clays were exfoliated and dispersed uniformly in the EPDM matrix. The glass transition temperature of EPDM/clay composites rose with increasing nanoclay content. The thermal degradation temperature was also increased by the increase of exfoliated nanoclay. The volume resistivity was also improved.

碩士
國立臺北科技大學
有機高分子研究所
93
Chloroprene rubber (CR)/organic modifier/sodium montmorillonite (NA-MMT) nanocomposites were prepared by melt intercalation. The morphology and thermal properties of the nanocomposites were studied using X-ray diffraction (XRD), transmission electron microscopy (TEM), and thermogravimetric analysis (TGA) and dynamic mechanical analysis (DMA). TEM showed that the silicate layers of clay were dispersed at the nano-scale level in the CR matrix containing less than 10 % of clay. XRD investigation also indicated that the silicate layers of clay were exfoliated, DMA was further performed to investigate the thermomechanical properties of CR–clay nanocomposites containing various amounts of clay. With the increase of organic modifier content, the glass-transition temperature and storage modulus of CR– clay nanocomposites increased .The tensile strength and elongation of the nanocomposites also increased.

博士
國立臺灣大學
高分子科學與工程學研究所
102
Layered silicate clays are natural crystallites and are well recognized for their organic intercalation for nanocomposite applications. In this study, a new mechanism is revealed by selection of hydrophobic polyetheramines with a poly(oxypropylene) (POP) backbone and a methyl terminus as the intercalation agent. Specifically, the monoamine with a molecular weight of 2000 g/mol widened the basal spacing of the layered sodium montmorillonite up to 74 A and further expansion to 84 A, 96 A, and 100 A by a second intercalation different from the ionic exchange reaction. Kinetic studies indicated that the first stage of intercalation occurred after a critical concentration of a monoamine, while the second stage had no critical concentration behavior. This two-step method shows the potentials for synthesizing suitable organoclay nanostructures for encapsulating phase change materials (PCM) and oil recovery from the spilt ocean. The exploration of the in-depth understanding of clay confinement chemistry leads the strategic design of new materials and oil recovery process. We further synthesized the phosphazene-amine adduct of hexachlorocyclophosphazene (HCP) and poly(oxypropylene)-diamines of 400 g/mol molecular weight (D400) by amine/chloride substitution and triethylamine removal of HCl. Subsequently, the adduct HCP-D400 was physically mixed with exfoliated silicate platelets (SP) to prepare the HCP-D400/silicate hybrids (HCP-D400/SP). The HCP-D400/MMT (HCP-D400 intercalated Na+-MMT) and HCP-D400/Na+-MMT (HCP-D400 physically mixed with Na+-MMT) were also prepared for comparison with HCP-D400/SP. A more homogeneous silicate distribution HCP-D400/SP than the HCP-D400/MMT counterparts in epoxy nanocomposites was revealed by SEM-EDX, XRD, and TEM analyses. The epoxy nanocomposite with 10 wt% of HCP-D400/SP, HCP-D400/MMT, and HCP-D400 had a degradation temperature at 80 % weight loss (T80 wt%) of 757 oC, 712 oC, and 519 oC, respectively, in comparison with the 500 oC of the pristine epoxy system. Anti-flame test confirmed that the HCP-D400/SP epoxy nanocomposite had a higher limit oxygen index (LOI) of 27.0 % than the HCP-D400/MMT counterpart (24.0 %). The degree of exfoliating the layered clay into random silicate platelets is the predominant factor for the thermal stability enhancement. It is also demonstrated that the co-presence of phosphazene-amines and silicate platelets has a synergistic effect in improving the thermal behavior of the nanocomposites.

博士
國立交通大學
應用化學系所
94
Nanoclay-filled polymeric systems offer the prospect of greatly improving many of the properties of their mother polymers. In the recent literature, there have been reports of nanoclay-filled polymeric systems that display significant improvements in tensile and thermal properties, heat distortion temperatures, and resistance to flammability and reduced permeability to small molecules and reduced solvent uptake. A common observation emerging from these studies is that the magnitude of improvement depends strongly on the state of dispersion of the clay layers in the polymer matrix. The experiment work in this dissertation was divided into four areas: 1. We have prepared polystyrene/clay nanocomposites using an emulsion polymerization technique. The nanocomposites were exfoliated at up to a 3 wt % content of pristine clay relative to the amount of polystyrene (PS). We used two different surfactants for the montmorillonite: the aminopropylisobutyl polyhedral oligomeric silsesquioxane (POSS) and the ammonium salt of cetylpyridinium chloride (CPC). The nanocomposite prepared from the clay treated with the POSS containing surfactant is exfoliated, while an intercalated clay was obtained from the CPC-treated surfactant. The value of Tg of the PS component in the nanocomposite is 8 °C higher than the virgin PS and its thermal decomposition temperature (21 °C) is also higher significantly. The presence of the POSS unit in the MMT enhances the thermal stability of the polystyrene. 2. We synthesized intercalation agent APB and prepared polystyrene/clay nanocomposites using an emulsion polymerization technique. We used two different intercalation agents to treat clay: the phosphonium salt (APP) and the ammonium salt (APB). We expected that the intercalation agent APB containing rigid adamantine group also has high thermal stability besides phosphonium group. The molecular weights of polystyrene (PS) obtained from the nanocomposite is slightly lower than the virgin PS formed under similar polymerization conditions. The coefficient of thermal expansion (CTE) was obtained from thermomechanical analysis. A 44~55 % decrease of CTE is observed for APB- and APP-intercalated clay nanocomposites relative to the pure PS. 3. We employed two surfactants for the montmorillonite: cetylpyridinium chloride (CPC) and the CPC/α-CD inclusion complex. The inclusion complex was characterized by X-ray diffraction, 13C CP/MAS NMR spectra, and 1H NMR spectroscopy, and TGA. The 1H NMR spectra of the complexes indicate that the stoichiometry of the complexes is 1:2 (i.e.,one CPC molecule and two α-CD units). The CPC/α-CD-treated clay is more effective than is virgin CPC-treated clay at enhancing the thermal stability of polystyrene. 4. We have used the solvent blending method to prepare polybenzoxazine/clay nanocomposites possessing various clay contents. We synthesized a monofunctional benzoxazine monomer (MBM) and then treated the clay with this intercalation agent. To better understand the curing kinetics of the polybenzoxazine/clay nanocomposites, we performed dynamic and isothermal differential scanning calorimetry (DSC) measurements. The Kissinger and Ozawa methods gave fairly close results for the calculated activation energies, which decreased upon increasing the clay content. The Kamal method－based on an autocatalytic model－suggested a total reaction order of between 2.4 and 2.8.

碩士
國立高雄應用科技大學
化學工程系碩士班
92
Poly (vinylidene chloride-co-vinyl chloride, PVDCB)/clay nanocomposites were prepared by melt blending of the polymer with a fluorinated synthetic mica (MEE), in the presence of dioctyl phthalate (DOP) which acted as a plasticizer. The nanostructure of the PVDCB/MEE nanocomposites was characterized by a wide angle X-ray diffractometer (WAXD) and a transmission electron microscope (TEM). It was found that both intercalated and exfoliated structures were present in the PVDCB/MEE nanocomposities. Below 8 wt% MEE, the intercalation effect of PVDCB/MEE nanocomposites decreased with MEE. The thermal stability of PVDCB/MEE nanocomposites was evaluated by a thermogravimetric analyzer (TGA). Results showed that, in nitrogen, PVDCB/MEE nanocomposites demonstrated a one-step thermal degradation behavior, and its thermal stability was significantly related to the morphology of nanocomposites, the DOP content and the degraded PVDC structure. In Air, PVDCB/MEE nanocomposites presented a two-step thermal degradation behavior. The flammability of PVDCB/MEE nanocomposites reduced as the amount of MEE increased. Below 5 wt% MEE, the glass transition temperature (Tg) of PVDCB/MEE nanocomposites increased with MEE. The crystallization temperature (Tc) of PVDCB showed a higher value in PVDCB/MEE nanocomposites and it can be related to the presence of DOP. Water vapor /oxygen barrier properties of PVDCB/MEE nanocomposites were evaluated by water vapor permeability tester and gas permeability tester, respectively. Results showed that water vapor /oxygen barrier properties were significantly improved in PVDCB/MEE nanocomposites and they can be related to the morphology of nanocomposites, the DOP content and the crystallinity of PVDCB.

In-situ polymerization is one of the most efficient methods for production of polymer clay nanocomposites. In-situ polymerization of olefins using coordination catalysts is a type of heterogeneous polymerization. In order to achieve acceptable clay nanolayer dispersion in the polyolefin matrix, the clay layer exfoliation and particle break up during the polymerization are essential requirements. A literature review on polyolefin/clay nanocomposite is given in Chapter 2. In Chapter 3, we present a new mathematical model, which is as an extension of the multigrain model (MGM), to describe the intercalative polymerization and expansion of clay interlayer spaces during polymerization using clay-supported metallocenes. The results from the model show that, under the studied conditions, mass transfer is not a strong factor controlling clay exfoliation and particle break up. If the polymerization active sites are supported uniformly on all clay surfaces, effective exfoliation will be achieved after a relative short polymerization time. In practice, obtaining good dispersion of clay nanolayers with uniform properties requires that the active sites be exclusively located on the clay nanolayer surfaces, and not extracted by the solvent to form a homogeneous solution. Factors favouring active site extraction would result in nanocomposites with poor properties. In addition, high polymerization activities, stable polymerization runs, and ease of supporting are other criteria for a successful in-situ polymerization. For this purpose we established a catalyst supporting method by which most of these requirements were met. In this method, the water content on the clay surface, which is considered as poison for the metallocene catalyst, was used to produce MAO upon reaction with trimethylaluminum (TMA). Using this method, polymerization was highly active in absence of MAO cocatalyst, knowing that MAO cocatalyst promotes active site extraction from the clay surface and results in poor powder morphology. Chapter 4 describes the development of this supporting methodology. Chapter 4 also investigates the effect of the organic modification type existing on the clay surface on the success of catalyst supporting and in-situ polymerization. We found that using the proposed supporting procedure, only tertiary ammonium type modification enhanced the in-situ polymerization, whereas the quaternary ammonium worsened the catalyst supporting efficiency and led to catalyst with poor or no polymerization activity. It is suggested that, in addition to enhancing clay surface-organic solvent compatibility (which facilitates catalyst supporting), the tertiary ammonium cation reacts with the in-situ produced MAO and increases the stability of the cocatalyst bonded to the clay surface. The effect of different polymerization conditions on the polymerization behavior and nanocomposite structural properties, such as catalyst loading during supporting, polymerization temperature and triisobutylaluminum (TIBA) concentration, were studied in Chapter 5. It was found that TIBA acts merely as scavenger. High polymerization activities were obtained with low Al/Zr ratios (Al from TIBA) and increased Al concentration decreased the polymerization activity and also the quality of powder morphology. Catalyst loading in the supporting step showed to have an important role in determining the final properties. The clay particles with higher catalyst loading resulted in better exfoliation and powder morphologies The effect of solvent type during catalyst supporting and polymerization was studied in Chapter 6. It was shown that catalyst supporting in n-hexane resulted in polymerizations with higher activities and polymers with higher molecular weight were produced. Polymerization with catalyst supported in hexane showed different ethylene uptake profiles, suggesting different mechanism of exfoliation. It is suggested that using this catalyst, the clay is mostly exfoliated before polymerization started. Similar to the original clay, the catalyst supporting efficiency on the organically modified clay was close to 100 percent. However, comparing the polymerization activities of these catalysts to those that were supported directly in the reactor just before the polymerization (in-reactor, or in-situ, supported catalysts) shows that a considerable fraction of the active sites are deactivated during the prolonged contact between catalyst and clay support surface. In Chapter 5, it was shown that the in-reactor supported catalyst had considerably higher polymerization activities, up to 40 percent of that of the homogeneous catalyst. Nanocomposites made with in-reactor supported catalysts had powder morphology and nanaolayer dispersion comparable to those made with clay-supported catalysts.

碩士
國立高雄應用科技大學
化學工程系碩士班
92
The propose of this study is to prepare polyaniline/synthetic mica nanocomposites by intercalating anilinium into pristine synthetic mica followed by the in-situ polymerization of the anilinium within the interlayer gallery. The synthesis and characterization of the polyaniline/synthetic mica intercalated nanocomposites with dangling chains are carried out in this study. The properties of polyaniline/synthetic mica nanocomposites are measured by wide angle X-ray diffraction (WAXD), FT-IR, UV-VIS, conductivity measurement, transmission electron microscopy(TEM), and scanning electron microscopy(SEM). The results illustrate that the conducting polyaniline intercalated into the galleries of the synthetic mica which demonstrating WAXD patterns with lower angles. The red shifting of UV-VIS spectra, the increasing length of conjugation of polyaniline chain were found when intercalation occurs. The degrading rate of polyaniline/synthetic mica nanocomposites at high temperature was greater than that of the bulk polyaniline and the degradation temperature was higher by 37℃. The FT-IR spectra show that a slight shift for the intercalated nanocomposites, due to the formation of hydrogen bonds between hydroxyl group and amine.

碩士
國立臺灣大學
高分子科學與工程學研究所
96
Magnetic and organic layered composite was prepared by the co-precipitation of organoclay with Fe(II)/Fe(Ⅲ) salts. Interaction mechanism of iron oxide particles into organoclay interlayer and their application for crude oil adsorption are studied. Part Ⅰ: The iron oxide particles were intercalated into the layered silicate clay by stepwise intercalation. The sodium montmorillonite (Na+–MMT) was modified by a series of poly(oxyalkylene)-amine salts to yield a spatially-expanded silicates (named as Organoclay) from the original 12 Å up to 91 Å. Combining the low-temperature-dispersible Organoclay with the iron-oxide particles ultimately produced a series of organoclay/iron oxide composite by the co-precipitation method. Two different mechanisms of adsorption and intercalation were found. The use of D4000 intercalated MMT at high d spacing (91 Å) allowed the incorporation of iron-oxide in the organoclay interlayer. As a result, the composite of Fe3O4/D4000/clay at 47 Å d spacing were obtained and observed the iron-oxide particles existed in the clay gallery by TEM. Part Ⅱ: In order to prepare a magnetic composite with functions for absorbing organics, high organic content in the clay layers is prepared. The TGA data of D4000-MMT/iron oxide composite showed the organic fraction up to 51 wt % and consequently dispersible in toluene (1 wt %). When applied for oil adsorption, the result of adsorption capacity at 4-fold of crude oil weight absorbed by the composites (by weight) was achieved. Due to the presence of iron-oxide particles (ca. 17 wt %), the oil-adsorbed Organoclay still retained the magnetic property and the compounds were movable by an applied magnetic field. Keywords: magnetic organoclay, layered silicate, iron oxide, crude oil, adsorption, intercalation.

碩士
國立中興大學
化學工程學系
93
A copolymer consisting of a hydrophobic polystyrene-b-poly(ethylene/butylene)-b-polystyrene (SEBS) backbone and multiple pendants of poly(oxyalkylene) (POA) quaternary ammonium salts was synthesized from a ring-opening reaction. The properties of the synthesized copolymer were examined by FT-IR, GPC, and titration. Layered silicates were intercalated with these comb-branched copolymers by an ion exchange reaction. The requisite intercalating agents were synthesized by grafting POA-amines on the maleated SEBS. The corresponding SEBS-POA amine salts were found to have two functions, to emulsify toluene/water mixtures to fine particle sizes of 60-70 nm in diameter and to exchange ions with sodium montmorillonite. The resultant silicate hybrids were characterized by X-ray diffractometry (XRD), fourier transmitter infrared spectrum analysis (FT-IR), differential scanning calorimeter (DSC) and transmission electron microscopy (TEM). Two types of intercalations with silicate d spacing of 18 Å and 50 Å were obtained, in which the dissimilarity is attributed to disparate polymer incorporations, POA pendants only or the combination of both the SEBS backbone and POA in the gallery. Furthermore, the two conformations of polymer-intercalated silicates are reversibly transformable by varying emulsion conditions, micelle sizes and solvents.

The reversible and topotactic insertion of guest species within layered host lattices, known as intercalation is a widely studied phenomena. The Layered Double Hydroxides (LDHs) or Anionic Alloys are important class of layered solids with its own distinct ion-exchange host-Guest Chemistry. The LDH structure may be derived from that of Brucite, Mg(OH)2, by random isomorphous substitution of Mg2+ ions by trivalent cations like Al3+, Ga3+ etc. This substitution leaves an excess positive charge on the layers, which is compensated by interlamellar anions. These ions are exchangeable and thus new functionalities can be introduced to ion exchange reactions. Insertion of neutral, non-polar or poorly water-soluble guest molecules remains a challenge. In the present study, two methodologies were adopted to extend the host-guest chemistry of LDHs to neutral and non-polar species, first by using Hydrophobic interaction and second, charge transfer (CT) interaction as driving force. Hlydrophobic interaction as driving force involves functionalization of the Mg-Al-LDH galleries as bilayers, thus covering the essentially hydrophilic interlamellar space of the LDH to one that is hydrophobic and able to solubilize neutral molecules like Anthracene. CT interaction as driving force, involves pre-functionalization of the galleries of the LDH with a donor species e.g. 4-aminobenzoic acid by conventional ion exchange methods to form a LDH-donor intercalated compound. This compound can selectively adsorb acceptor species like Chloranil, Tetracyanoquinodimethane etc. into the interlamellar space of the solid by forming donor-acceptor complexes. The confined donor-acceptor complexes have been characterized by X-Ray Diffraction, UV-Visible, Fourier Transformed Infra-Red and Raman Spectroscopy, Molecular Dynamics Simulations were able to reproduce the experimental results. One dimensional gold nanostructure like nanorods (AuNRs) have received great attention due to their size dependent optical properties, Extending these applications requires assembling the AuNRs into one-, two- and if possible three-dimensional architectures. Several approaches have been developed to assemble AuNRs in two-orientation modes namely end-to-end and side-to-side. The present study self-assembly of the AuNRs has been achieved by anchoring β-cyclodextrin (β-CD) cavities to the nanorods surface. The host-guest chemistry of β-CD has been exploited to assemble the AuNRs. Our strategy was to use a guest molecule that is capable to link β-CD into 1:2 host-guest fashions to link up two β-CD capped nanorods. The guest molecule chosen for the present study was 1,10-phenanthroline. Linkage between the ends of rods leading to V-shaped rods dimmer assembly and side-to-side assembly was achieved by varying the extent of cyclodextrin capping of the AuNRs followed by the addition of linker, 1,10-phenanthroline. The formation of the assembly was characterized using UV-Visible-Near-IR Spectoscopy and Transmission Electron Microscopy.