Produire à grande échelle des nanotubes de carbone en maîtrisant les principaux paramètres de croissance et la morphologie de ces matériaux est un enjeu important en vue de leur exploitation industrielle dans de nombreux domaines tels que l’élaboration de composites ou le stockage de l’énergie. C’est dans ce contexte que s’inscrit ce travail, basé sur la technique de dépôt chimique à partir d’une phase vapeur (CVD) mise en oeuvre dans un procédé faisant appel à un lit fluidisé de particules catalytiques (FB-CCVD). Dans un premier temps, nous avons étudié le catalyseur mis au point par la société Arkema, de sa préparation à son utilisation en catalyse pour la croissance de nanotubes de carbone multi-parois. Nous avons ainsi mis en évidence que la phase active était principalement localisée à la surface du support sous la forme d’une gangue discontinue d’hématite. Lors de la synthèse, nous avons constaté deux régimes cinétiques différents que nous avons confrontés aux évolutions physico-chimiques du matériau au cours du dépôt. Par la suite, nous avons préparé à partir du procédé Arkema différents catalyseurs bimétalliques afin d’augmenter le rendement de la synthèse de nanotubes de carbone et de diminuer leur diamètre. Un système à base de fer et de molybdène a montré une activité trois fois supérieure au catalyseur initial sous réserve de travailler à une température particulière. Enfin, dans une dernière partie, nous avons tenté de proposer une explication sur le rôle joué par le molybdène lors de la croissance des nanotubes de carbone. Nos observations nous ont mené à la préparation de catalyseurs coeur-écorce à base de fer et de molybdène présentant des activités supérieures à un système homogène. / The large scale production of carbon nanotubes associated with control of the main growth parameters and of the morphology is a challenging aim for future industrial exploitation of these nanostructured materials in numerous fields like composite production and energy storage. This work based on the fluidized bed catalytic chemical vapour deposition technique (FB-CCVD) lies in this industrial framework. At first, we have studied the catalyst produced by Arkema, from its synthesis to its use for carbon nanotubes growth. We have shown that the active phase is mainly located at the support surface in the form of a discontinuous film of hematite. During the synthesis, we have noticed two kinetic regimes that we analysed through caracterisation of the material at different times of the reaction. Then, we have prepared bimetallic catalysts using the Arkema process in order to improve the reaction yield and to decrease carbon nanotubes diameter. We have discovered thaht an iron and molybdenum based catalyst shows three times higher activity than the classic one, if we work at a specific temperature. At last, we have tried to explain the role played by molybdenum in the growth of carbon nanotubes. Our findings have lead us to develop core shell iron and molybdenum based catalysts presenting higher activity than the homogeneous sytem.

In this study, we propose a multi-walled carbon nanotube epoxy composite sensor for force and pressure sensing in the range of 50 N–2 kN. A manufacturing procedure, including material preparation and deposition techniques, is proposed. The electrode dimensions and the layer thickness were optimized by the finite element method. Temperature compensation is realized by four nanocomposites elements, where only two elements are exposed to the measurand. In order to investigate the influence of the filler contents, samples with different compositions were prepared and investigated. Additionally, the specimens are characterized by cyclical and stepped force/pressure loads or at defined temperatures. The results show that the choice of the filler content should meet a compromise between sensitivity, temperature influence and noise behavior. At constant temperature, a force of at least 50N can be resolved. The measurement error due to the temperature influence is 150N in a temperature range of –20°C–50°C.

In this paper, we propose strain-sensitive thin films based on chemically reduced graphene oxide (GO) and multi-walled carbon nanotubes (MWCNTs) without adding any further surfactants. In spite of the insulating properties of the thin-film-based GO due to the presence functional groups such as hydroxyl, epoxy, and carbonyl groups in its atomic structure, a significant enhancement of the film conductivity was reached by chemical reduction with hydro-iodic acid. By optimizing the MWCNT content, a significant improvement of electrical and mechanical thin film sensitivity is realized. The optical properties and the morphology of the prepared thin films were studied using ultraviolet-visible spectroscopy (UV-Vis) and scanning electron microscope (SEM). The UV-Vis spectra showed the ability to tune the band gap of the GO by changing the MWCNT content, whereas the SEM indicated that the MWCNTs were well dissolved and coated by the GO. Investigations of the piezoresistive properties of the hybrid nanocomposite material under mechanical load show a linear trend between the electrical resistance and the applied strain. A relatively high gauge factor of 8.5 is reached compared to the commercial metallic strain gauges. The self-assembled hybrid films exhibit outstanding properties in electric conductivity, mechanical strength, and strain sensitivity, which provide a high potential for use in strain-sensing applications.

Dans ce travail, nous décrivons la méthode de synthèse, la structure, les propriétés et quelques applications en catalyse de différentes formes du carbone, en particulier les nanostructures carbonées (Chapitre I). La technique de dépôt chimique en phase vapeur en réacteur à lit fluidisé a été utilisée pour le dépôt de métaux ou d’oxydes de métaux sur des supports comme l’alumine ou la silice. Le matériau résultant est utilisé comme catalyseur pour la synthèse de diverses nanostructures carbones par dépôt chimique en phase vapeur catalytique : nanotubes de carbone mono- et multi-feuillets (SWCNTs, MWCNTs), nanofibres de carbone (CNFs), et des nanotubes de carbone (N-MWCNTs) ou nanofibres (N-CNFs) dopés en azote (Chapitre II). Après dissolution du catalyseur par un traitement a l'acide sulfurique ou par la soude, suivit dans le cas des MWCNTs et CNFs, par un traitement à l'acide nitrique pour générer des fonctions carboxyliques de surface, les nanostructures carbonées ont été utilisées comme supports de catalyseurs. L’hydrogénation du cinnamaldehyde a été choisit comme réaction modèle pour comparer les performances de différents catalyseurs bimétalliques de Pt-Ru en fonction de la nature du support. Une étude paramétrique détaillée ainsi que l'étude de l'effet d'un traitement thermique sur l'amélioration des performances du catalyseur de Pt-Ru/MWCNT sont présentes. Une explication de l'augmentation des performances catalytiques sera proposée après analyses du catalyseur par HREM, EDX, EXAFS et WAXS (Chapitre III). Les nanostructures carbonées préparées seront également testées comme supports conducteurs d'électrocatalyseurs pour l'élaboration d'électrodes de "polyelectrolyte membrane fuel cells" (PEMFC). / In this work, we describe the synthesis, structure, physical properties and some applications in catalysis of previously known carbon allotropes, and recently discovered carbon nanostructure (Chapter I). First, FB-OM-CVD deposition was used for metal or metal oxide deposition on metal oxide supports like alumina or silica, leading to the production of supported catalysts. The resulting material was used as catalyst for catalytic chemical vapor deposition of carbonaceous nanostructures i.e single- and multi-walled carbon nanotubes (SWCNTs, MWCNTs), carbon nanofibers (CNFs), and nitrogen doped carbon nanotubes (N-MWCNTs) and nanofibers (N-CNFs) (Chapter II). After catalyst removal by a H2SO4 or NaOH treatments and carboxylic surface group generation by a HNO3 treatment in the case of MWCNTs and CNFs, the carbon nanostructures were used as supports for heterogeneous catalysis. The hydrogenation of cinnamaldehyde was used as a model reaction to compare the performance of different bimetallic Pt-Ru catalysts as a function of the nature of the support. Detailed parametric studies as well as the effect of a heat treatment on the performance improvement of the Pt-Ru/MWCNT catalyst are presented. An explanation for the increase of performances upon heat treatment will be proposed after HREM, EDX, EXAFS and WAXS characterization of the catalyst (Chapter III). The prepared carbon nanostructures were also tested as supports for Pd based electrocatalysts for direct alkaline fuel cells applications in both cathodes for the ORR reaction and anodes for alcohols oxidation.

<p>Fullerenes have been shown to constitute a prototypical building block for truly nanometer-sized devices and exotic nanounit-based materials, e.g., high-temperature superconductors. This makes the detailed understanding of fullerene electronic states in compounds and at interfaces of primary importance, since the high symmetry of the molecule greatly </p><p>simplifies the starting point of the analysis. Carbon nanotubes, which combine one macroscopic with two nanoscopic dimensions, are perhaps of even greater practical interest.</p><p>Angle-dependent electron spectroscopies have been employed in the present work to study these materials, characterizing their structure, bonding, and electronic states. For solid C₆₀, the photoelectron angular distribution has been found to be essentially that of the free molecule, modified by solid state scattering; a similar distribution is found for K₃C_60.</p><p>The surface and bulk electronic structure of K₃C₆₀ has been identified by angle-dependent core and valence photoelectron spectroscopy (PES) and x-ray emission spectroscopy. An insulating surface layer has been identified for this high-temperature superconductor.</p><p>Angle-dependent valence PES is used to investigate the electronic states of C₆₀/Al(110). Electron correlations are found to be the origin of the splitting observed in the molecular orbitals, which is quite sensitive to the molecular orientation. The components of the highest occupied molecular orbital are differentiated according to their overlap with the substrate.</p><p>A rigid shift of valence- and core-levels has been observed even for ionic and covalent C₆₀compounds, reflecting the efficient static polarizability screening of the molecule. </p><p>The alignment of multi-walled carbon nanotubes has been investigated by x-ray absorption spectroscopy, using the spectral intensity ratio of π*- and *-resonances. Core level combined with valence PES shows that the degree of defect structure varies from position to position on the sample. Valence photoelectron spectra of defect-free sample spots closely resembles the total DOS of graphite.</p>

Fullerenes have been shown to constitute a prototypical building block for truly nanometer-sized devices and exotic nanounit-based materials, e.g., high-temperature superconductors. This makes the detailed understanding of fullerene electronic states in compounds and at interfaces of primary importance, since the high symmetry of the molecule greatly simplifies the starting point of the analysis. Carbon nanotubes, which combine one macroscopic with two nanoscopic dimensions, are perhaps of even greater practical interest. Angle-dependent electron spectroscopies have been employed in the present work to study these materials, characterizing their structure, bonding, and electronic states. For solid C60, the photoelectron angular distribution has been found to be essentially that of the free molecule, modified by solid state scattering; a similar distribution is found for K3C60. The surface and bulk electronic structure of K3C60 has been identified by angle-dependent core and valence photoelectron spectroscopy (PES) and x-ray emission spectroscopy. An insulating surface layer has been identified for this high-temperature superconductor. Angle-dependent valence PES is used to investigate the electronic states of C60/Al(110). Electron correlations are found to be the origin of the splitting observed in the molecular orbitals, which is quite sensitive to the molecular orientation. The components of the highest occupied molecular orbital are differentiated according to their overlap with the substrate. A rigid shift of valence- and core-levels has been observed even for ionic and covalent C60 compounds, reflecting the efficient static polarizability screening of the molecule. The alignment of multi-walled carbon nanotubes has been investigated by x-ray absorption spectroscopy, using the spectral intensity ratio of π*- and *-resonances. Core level combined with valence PES shows that the degree of defect structure varies from position to position on the sample. Valence photoelectron spectra of defect-free sample spots closely resembles the total DOS of graphite.

Αντικείμενο της παρούσας διατριβής, ήταν η διερεύνηση της διεπιφάνειας ανθρώπινων μεσεγχυματικών κυττάρων (Human Mesenchymal Stem Cells, hMSCs) -Νανοσωλήνων Άνθρακα Πολλαπλού Τοιχώματος (Multi Walled Carbon Nanotubes, MWCNTs) υπό στατικές και δυναμικές συνθήκες. Οι MWCNTs έχει αποδειχθεί ότι, έχουν μοναδικές ηλεκτρικές και φυσικές ιδιότητες, μηχανική αντοχή και χαμηλή πυκνότητα, χαρακτηριστικά που τους καθιστούν εξαιρετικά ελκυστικούς για το σχεδιασμό βιοϋλικών για ορθοπαιδικές εφαρμογές. Αρχικά, μελετήθηκε η βιοσυμβατότητα των hMSCs σε επιφάνειες MWCNTs, ως προς την κυτταροτοξικότητα, τη μορφολογία, τον πολλαπλασιασμό, τη διαφοροποίηση και την οργάνωση του κυτταροσκελετού. Το υπόστρωμα των MWCNTs ευνόησε την εξάπλωση των κυττάρων, προήγαγε τον πολλαπλασιασμό και προώθησε τη διαφοροποίηση των hMSCs σε οστεοβλάστες, όπως έδειξε η έκφραση αλκαλικής φωσφατάσης, οστεοποντίνης και οστεοκαλσίνης. Μελετήθηκε η γονιδιακή έκφραση των ιντεγκρινικών υποδοχέων, υπεύθυνων για την προσκόλληση των κυττάρων στους MWCNTs. Με την τεχνική του περιστρεφόμενου δίσκου, εκτιμήθηκε η δύναμη προσκόλλησης των hMSCs στους MWCNTs και η επίδραση της κάθε ιντεγκρίνης στη μεταβολή της δύναμης προσκόλλησης. Για τη διερεύνηση της απόκρισης των οστεοβλαστών στη μηχανική φόρτιση, τα προσκολλημένα κύτταρα στους MWCNTs καταπονήθηκαν για 3 και 24 ώρες, με σύστημα μηχανικής φόρτισης βασισμένο στην Αρχή Κάμψης Τεσσάρων Σημείων. Τα αποτελέσματα έδειξαν ότι, η φόρτιση επηρεάζει θετικά την έκφραση γονιδίων προσκόλλησης και δεικτών διαφοροποίησης. Επιπρόσθετα, μελετήθηκε η συμπεριφορά των hMSCs ως προς την κυτταροτοξικότητα, τον πολλαπλασιασμό, τη διαφοροποίηση, την οργάνωση του κυτταροσκελετού και την έκφραση γονιδίων προσκόλλησης, σε τροποποιημένες επιφάνειες MWCNTs με υδροξυλομάδες, καρβοξυλομάδες και αμινομάδες. Τα αποτελέσματα έδειξαν ότι, η αμινοτροποποιημένη επιφάνεια ευνόησε σημαντικά την κυτταρική συμπεριφορά σε σύγκριση με τις άλλες δύο επιφάνειες. Τέλος, μελετήθηκε η επίδραση της τοπογραφίας με χρήση κάθετα ευθυγραμμισμένων MWCNTs, σε σύγκριση με τυχαία προσανατολισμένους MWCNTs. Η απόκριση των hMSCs στους κάθετα ευθυγραμμισμένους MWCNTs ήταν καλύτερη σε σύγκριση με τους τυχαία προσανατολισμένους, τόσο ως προς τον πολλαπλασιασμό και τη διαφοροποίηση, όσο και ως προς την οργάνωση του κυτταροσκελετού. Τα αποτελέσματα της διατριβής είναι υποσχόμενα για το μελλοντικό σχεδιασμό βιοϋλικών με MWCNTs, με τελικό σκοπό την εφαρμογή σε θεραπείες στις οποίες απαιτείται ανακατασκευή του οστού. / The aim of the present study was the investigation of the interface of human Mesenchymal Stem Cells (hMSCs) – Multiwalled Carbon Nanotubes (MWCNTs), under static and dynamic conditions. MWCNTs have been proven to obtain unique electric and physical properties, mechanical strength and low density, which render them highly attractive for the design of biomaterials for orthopaedic applications. Firstly, the biocompatibility of MWCNTs was studied, in terms of hMSCs cytotoxicity, morphology, proliferation, differentiation, cytoskeleton organization and toxicity. The substrate of MWCNTs favored cell spreading, increased proliferation and promoted cell differentiation, as measured by the expression of alkaline phosphatase, osteopontin and osteocalcin. The gene expression of integrin receptors responsible for cell attachment on MWCNTs was studied. Using the Spinning Disc Technique, the attachment strength of hMSCs on MWCNTs was evaluated, as well as the impact of each integrin to the alteration of attachment strength. In order to investigate the cell response to mechanical loading, the attached cells on MWCNTs were stressed for 3 and 24 hours, using a system for mechanical loading based on the 4-point bending principle. Results showed that loading positively induces the expression of genes associated with attachment and differentiation markers. Additionally, the cell behavior concerning proliferation, differentiation, cytoskeleton organization, apoptosis and gene expression associated with attachment, was studied on MWCNTs after surface modification with hydroxyl-, carboxyl-, and amino- groups. The findings indicated that the amino- modified surface significantly favored the cell behavior, compared to the other two surfaces. Lastly, the topography effect was studied using vertically aligned MWCNTs. Cell response was found better on the vertically compared to the randomly oriented, in terms of proliferation, differentiation and cytoskeleton organization. The findings of the study are promising for the future design of biomaterials of MWCNTs, aiming for application in therapies where bone reconstruction is demanded.

Made available in DSpace on 2016-12-08T17:19:26Z (GMT). No. of bitstreams: 1 Marindia Decol.pdf: 3575085 bytes, checksum: bed6c0ed662d3c76c64b6cfdac902d8b (MD5) Previous issue date: 2015-07-15 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Poly (lactic acid) (PLA) is a rigid and brittle thermoplastic polymer, and poly (&#949;-caprolactone) (PCL) is a thermoplastic polymer of lower rigidity and higher toughness than PLA. Combination of these properties through the blend PLA/PCL has been studied successfully to change the final properties of the PLA. The addition of multiwalled carbon nanotubes (MWCNT) in the blend PLA/PCL may induce peculiar orphologies depending on their location, resulting in the getting new properties or modifying the properties of the PLA matrix. This study aimed to evaluate the effect of adding the PCL, the compatibilizer Cesa-mix and MWCNT the final properties of the PLA. Mixtures were prepared in internal mixer chamber coupled to a torque rheometer and subjected to characterizations of morphological, thermal, mechanical and electrical properties. In the morphological analysis, there was a 37% reduction in the average size of the phases of the PCL blends PLA/PCL with the addition of compatibilizer Cesa®- mix, a heterogeneous distribution of MWCNT the PLA matrix and a selective location of MWCNT in phase PCL. With respect to thermal properties, the addition of the compatibilizing PCL and did not significantly affect the thermal degradation onset temperature (Tonset) of the PLA, but the addition of the MWCNT in PLA resulted in decreased Tonset nanocomposites. The melting temperature did not change significantly with the addition of PCL, the compatibilizer and MWCNT on the PLA matrix. Already cold crystallization temperature decreased and the degree of crystallinity of the PLA increased with the addition of PCL blends and MWCNT in nanocomposites. Decreases of 35% on elastic hardness and 29% in modulus of elasticity was observed with the addition of PCL and compatibilizer Cesa®-mix in the blends PLA/ PCL/AC/2,5%. With the addition of MWCNT was observed an increase of 6,8% on elastic hardness and 8% in the modulus of elasticity of PLA/CNT mixtures with 1,0% w/w. Blends of PLA/PCL with 0,5% and 1,0% w/w CNT with and without compatibilizer, had a decrease in modulus of elasticity and elastic hardness. No significant changes were observed in the electric resistance of the samples with the addition of the compatibilizer, the PCL and MWCNT with 0,5% and 1,0% w/w. Selective location of MWCNT the PCL phase had great influence on morphological, thermal, mechanical and electrical properties of nanocomposites. / O poli(ácido lático) (PLA) é um polímero termoplástico rígido e frágil, e a poli(&#949;-caprolactona) (PCL) é um polímero termoplástico de menor rigidez e maior tenacidade que o PLA. A combinação destas propriedades através da blenda PLA/PCL tem sido estudada com êxito no auxílio à alteração das propriedades finais do PLA. A adição de nanotubos de carbono de paredes múltiplas (NTCPM) na blenda PLA/PCL pode induzir a morfologias peculiares dependendo da sua localização, resultando na obtenção de novas propriedades ou na alteração das propriedades da matriz PLA. Este trabalho teve como objetivo avaliar o efeito da adição do PCL, do compatibilizante Cesa-mix e dos NTCPM nas propriedades finais do PLA. As misturas foram preparadas em misturador de câmara interna acoplado a reômetro de torque e submetidas à caraterizações das propriedades morfológicas, térmicas, mecânicas e elétricas. Na análise morfológica, observou-se uma redução de 37% no tamanho médio das fases de PCL nas blendas PLA/PCL com a adição do compatibilizante Cesa®- mix, uma distribuição heterogênea dos NTCPM na matriz PLA e uma localização seletiva dos NTCPM na fase PCL. Em relação às propriedades térmicas, a adição do PCL e do compatibilizante não afetaram significativamente na temperatura de início de degradação térmica (Tonset) do PLA, porém a adição de NTCPM no PLA resultou em decréscimo na Tonset dos nanocompósitos. A temperatura de fusão não apresentou variação significativa com a adição do PCL, do compatibilizante e dos NTCPM na matriz PLA. Já a temperatura de cristalização a frio diminuiu e o grau de cristalinidade do PLA aumentou com a adição de PCL nas blendas e dos NTCPM nos nanocompósitos. Diminuições de 35% na dureza elástica e de 29% no módulo de elasticidade foram observadas com a adição do PCL e do compatibilizante Cesa®-mix nas blendas PLA/PCL/AC 2,5%. Com a adição de NTCPM foi observado um aumento de 6,8% na dureza elástica e de 8% no módulo de elasticidade das misturas PLA/NTC com 1,0% m/m. As misturas de PLA/PCL com 0,5% e 1,0% m/m de NTC com e sem compatibilizante, tiveram um decréscimo no módulo de elasticidade e na dureza elástica. Não foram verificadas alterações significativas na resistência elétrica das amostras com a adição do compatibilizante, do PCL e dos NTCPM com 0,5% e 1,0% m/m. A localização seletiva dos NTCPM na fase PCL teve grande influência nas propriedades morfológicas, térmicas, mecânicas e elétricas dos nanocompósitos.

Segmental chain dynamics in polymer blends is a very important topic, not only from a fundamental point of view but also from technological applications. Because of the difficulties in the commercialization of new polymers, industries have turned increasingly towards blending of polymers to optimise their end use (mechanical, rheological) properties. The design of tailor-made materials would be enormously facilitated by the understanding of the blending phenomena at a molecular level. The key question to address is to understand the dynamics of each component of the blend modified by blending? The thesis has systematically studied the effect of multiwalled carbon nanotubes on the chain dynamics, demixing temperature, structural properties and evolution of morphology in a classical miscible polymer blend system (PVDF/PMMA). The thesis comprises of six chapters, Chapter 1 is an introductory chapter that outlines the fundamentals of polymer blends, crystallisation in polymer blends and the basics of dielectric spectroscopy. As one of the rationales of this work is to systematic study whether phase separated in these blends can be used as a tool to develop membrane for water purification. This chapter also gives an overview of the reported studies of ultrafiltration membrane fabrication, factors affecting membrane morphology and flux. In Chapter 2, the materials and methodology used to carry out experiments and the experimental procedures are discussed. Chapter 3 discusses the effect of concentration of PMMA and amine functionalized multiwalled carbon nanotubes (MWNTs) on the crystallisation induced phase separation using FTIR, XRD, POM and shear rheology. Electron microscopy and selective etching confirmed the localisation of MWNTs in the PVDF phase of the blends. Blends with MWNTs facilitated in heterogeneous nucleation manifesting in an increase in crystallisation temperature. The crystallisation induced phase separation in PVDF/PMMA blends was observed to influence the interconnected network of MWNTs in the blends. Chapter 4 discuss the effect of concentration of PMMA and MWNTs on the miscibility and the segmental relaxations was probed in situ by DSC and dielectric relaxation spectroscopy (DRS). The dynamic heterogeneity in the blends as manifested by the presence of an extra relaxation at a higher frequency at or below the crystallisation induced phase separation temperature was also discussed. We found that PVDF/PMMA blend (PVDF ≥ 80 wt%) exhibits three distinct relaxations; αc corresponding to crystalline PVDF, αβ segmental relaxation of PMMA and αm of amorphous miscibility whereas all relaxations overlap and constitute a single broad relaxation in PVDF/PMMA blend (PVDF ≤ 70 wt%). This confirms that there is a certain composition width in this blend wherein three distinct relaxations can be traced. This could due to many reasons like the width of crystal-amorphous interphase in the crystal lamellae, crystal size and morphology is strongly contingent on the concentration of PMMA. Relaxations are not very distinct in presence of MWNTs due to defective spherulites that shift the relaxations towards a higher frequency. Chapter 5 has attempted to tune the microporous morphology of PVDF membranes using crystallisation induced phase separation in PVDF/PMMA blends. As PVDF/PMMA is a melt-miscible blend, the samples were allowed to crystallise and the amorphous PMMA phase, which isolates in the interlamellar or inter-spherulitic regions in the blends, was etched out to generate microporous structures. The pore sizes can be tuned by varying the PMMA concentration in the blends. We observed that 60/40 PVDF/PMMA blends showed larger pores as compared to 90/10 PVDF/PMMA blends. We further modified PVDF membranes by sputtering silver on the surface. The bacterial cell viability was distinctly suppressed (99 %) in silver sputtered membranes. The ICP analysis suggests that slow Ag+ ions release from the sputtered membrane surface assisted in developing antibacterial surface. Our findings open new avenues in designing water filtration membranes and also help in understanding the crystallisation kinetics for tuning pore size in membranes. Chapter 6 summarises the important results of this work. MWNTs act as hetero nucleating agent and specifically interact with PVDF thereby influences the dynamics of PVDF chains. MWNTs can also restrict the amorphous segmental mobility and can influence the intermolecular cooperativity and coupling. The crystallisation induced phase separation in various blends can result in various crystalline morphologies depending on the PVDF concentration. By selectively etching PMMA from the phase-separated blends, microporous morphology can be generated

Abstract The main objectives of this thesis are to synthesize macroscopic well-aligned multi-walled carbon nanotube films and, based on their electrical conductivity, porosity and structural uniformity, highlight potential applications for further development. In this thesis, catalytic chemical vapour deposition from ferrocene-xylene precursors is optimized to grow high quality films of long, aligned multi-walled carbon nanotubes on lithographically patterned templates in high (~800ºC) temperatures. The impacts of reaction time, temperature and precursor concentration on MWCNT film quality (film thickness, purity, density and nanotube diameter distribution) are studied. Because of the excellent control of growth selectivity and film thickness inherent to the method, several interesting applications, including solar cell and capacitor electrodes, contact brushes, coolers, particulate filters and catalyst membranes, have been developed for nanotube films in collaboration between Finnish and international research groups over the past few years. In this thesis, advanced capacitor electrodes with improved charge storage and efficient particulate filters are discussed in closer detail. As the high temperatures used for growing high quality carbon nanotubes often cause complications in cases where nanotubes need to be directly integrated with other materials, experiments were also conducted with the aim of making the growth temperature as low as possible. After testing several catalyst and precursor combinations, cobalt nanoparticles deposited on silica surfaces were found to form carbon nanotubes from vaporized cyclopentene oxide precursor already at 470°C. The results show that catalytic chemical vapour deposition is a feasible and versatile method that can be combined with photolithography to produce multi-walled carbon nanotube films with desired footprint area and thickness on various substrates. The demonstrated new applications and technical solutions are expected to contribute to further development leading to competitive practical devices based on carbon nanotubes. / Tiivistelmä Tämän väitöstyön päätavoitteina ovat makroskooppisten, yhdensuuntaisista moniseinämäisistä hiilinanoputkista koostuvien kalvojen valmistaminen ja sovellutusten esittäminen perustuen kalvojen sähkönjohtavuuteen, huokoisuuten ja rakenteelliseen yhdenmukaisuuteen. Katalyyttis-kemiallinen höyryfaasikasvatusmenetelmä on optimoitu korkealaatuisten, yhdensuuntaisista, pitkistä moniseinämäisistä hiilinanoputkista koostuvien kalvojen tuottamiseen korkeissa lämpötiloissa (~800ºC) fotolitografialla kuvioiduille kasvualustoille käyttäen ferroseeni/ksyleeni-lähtöainetta. Reaktioajan, lämpötilan ja lähtöainepitoisuuden vaikutusta nanoputkikalvon laatuun on tutkittu tarkastelemalla kalvon paksuutta, puhtautta, tiheyttä ja nanoputkien läpimittajakaumaa. Erinomaisen kasvuselektiivisyyden ja kalvon paksuuden kontrolloimisen ansiosta nanoputkikalvoja voidaan räätälöidä useisiin mielenkiintoisiin sovellutuksiin (esim. aurinkokennot ja kondensaattorin elektrodit, hiiliharjat, jäähdyttimet, partikkelisuodattimet ja katalyyttikalvot), joita olemme kehittäneet viime vuosina yhdessä suomalaisten ja kansainvälisten tutkimusryhmien kanssa. Tässä väitöstyössä on tarkasteltu lähemmin uudentyyppisiä kondensaattorielektrodeja, joilla on parantunut sähkövarauksen varastointikyky, sekä tehokkaita partikkelisuodattimia. Hiilinanoputkien kasvattaminen korkeissa lämpötiloissa aiheuttaa usein ongelmia integroitaessa nanoputkia toisiin materiaaleihin. Tästä johtuen tutkimuksessa pyrittiin saamaan nanoputkien kasvatuslämpötila mahdollisimman alhaiseksi testaamalla useita lähtöaine-katalyytti-kombinaatioita, joista koboltti-nanopartikkelit piidioksidin päällä ja syklopenteenioksidi lähtöaineena muodostivat hiilinanoputkia jo 470°C:ssa. Tulosten perusteella katalyyttis-kemiallinen höyryfaasikasvatusmenetelmä yhdistettynä fotolitografiaan on hyvin monipuolinen tapa tuottaa moniseinämäisiä hiilinanoputkia halutulla kuviolla ja kalvonpaksuudella erilaisille substraateille. Tässä väitöstyössä demonstroitujen uusien sovellutusten ja teknisten ratkaisujen odotetaan johtavan uusiin, hiilinanoputkiin perustuviin kilpailukykyisiin käytännön laitteisiin.