Advanced dispersants were discovered for the fabrication of homogeneous suspensions of multi-walled carbon nanotubes (MWCNT), graphene, and manganese dioxide (MnO2) in both ethanol and water. Thin films of MWCNT, graphene, MnO2, composite films of MWCNT-MnO2 and MWCNT-graphene were prepared using electrophoretic deposition (EPD) and electrolytic deposition (ELD) methods. The mechanisms of dispersion and deposition were investigated. Cathodic EPD was achieved for MWCNT and graphene using positively charged dispersants. Co-deposition of MWCNT and MnO¬2 was performed using a co-dispersant, which dispersed both MWCNT and MnO2 in ethanol. Composite films were tested for electrochemical supercapacitor (ES) purposes. Pulse ELD was used to deposit porous MnO2 coatings on Ni foam substrates from KMnO4 solutions. Cathodic deposition offered advantages, compared to anodic deposition, because the problems, related to anodic dissolution of metallic substrates, can be avoided. The pulse ON/OFF times had significant influence on the morphology and structure of MnO2 films, which further determined the capacitive performance. The influence of MnO2 film thickness on specific capacitance was investigated. Porous and conductive vanadium nitride (VN) was synthesized using melamine as a reducing agent. To further improve film conductivity and specific surface area, MWCNT were incorporated into VN matrix during synthesis. VN-MWCNT composite electrodes and VN-MWCNT/MnO2-MWCNT asymmetric supercapacitor cells were fabricated and tested. The electrodes and cells exhibited excellent electrochemical capacitive performance with good cyclic stability. The asymmetric supercapacitor device showed a voltage window up to 1.8 V, which was the combination of voltage window of VN-MWCNT (-0.9 V--0 V) and MnO2-MWCNT (0 V--0.9 V). Polypyrrole (PPy) coated MWCNT were synthesized in ethanol with ammonium peroxydisulfate solution as an oxidant. The effects of dopants to PPy morphology and conductivity was investigated. Dopants with electrochemical active groups were selected for the synthesis of PPy nanoparticles, where dopants also contributed to the capacitance of the polymer based materials. Both PPy-MWCNT/PPY-MWCNT symmetric supercapacitors and VN-MWCNT/PPY-MWCNT asymmetric supercapacitors were fabricated and tested, where the voltage windows were 0.9 V for the former and 1.3 V for the later. The increase of voltage window was ascribed to the asymmetric structure and negative voltage window of VN-MWCNT composite. / Thesis / Doctor of Philosophy (PhD)

In this study, polypyrrole (PPy) prepared by chemical and electrochemical polymerization was investigated as the electrode of electrochemical supercapacitor (ES). New strategies were developed for the fabrication of nano-structured PPy and PPy based nano-composites, which included discovery of advanced anionic dopants and multi-functional nano-crystals, and development of co-dispersing agents. These methods improved the capacitive performance and cycle stability of PPy electrodes. The results indicated that high material loading and good capacitance retention of PPy was achieved using an electrochemical polymerization method and Ni plaque as the current collectors. Nano-crystalline (CTA)2S2O8 formed by a chemical precipitation method from solutions, containing anionic oxidant (S2O82-) and cationic surfactant (CTA+), could be used as the oxidant to synthesize PPy nano-fibers. We demonstrated that multi-wall carbon nanotubes (MWCNT) can be efficiently dispersed using such nano-crystals. Application of multi-functional nano-crystals is a conceptually new approach for the fabrication PPy coated MWCNT. Moreover, safranin and malachite green were found as universal dispersing and charging agents for cataphoretic deposition of graphene, MWCNT and PPy nano-fibers. It opens new strategies in colloidal and electrochemical processing of PPy nano-composites for ES electrodes. PPy coated MWCNT, prepared by the multi-functional nano-crystals (CTA)2S2O8, was employed for the fabrication of N-doped activated carbon-coated MWCNT (N-AC-MWCNT). The obtained N-AC-MWCNT was uniformly coated and possessed with high surface area. The use of N-AC-MWCNT enabled the fabrication of ES electrodes with high mass loading and high active material to current collector mass ratio. Symmetric and asymmetric ES cells, fabricated by N-AC-MWCNT and aqueous Na2SO4 electrolyte, showed high specific capacitance, good capacitance retention and large voltage window. The positive electrode of asymmetric ES, MnO2 coated MWCNT, was successfully prepared by the chemical reaction between KMnO4 and N-AC-MWCNT. The problem of degradation of MWCNT was avoided by the use of N-AC as the sacrificial carbon. Significant progress on ES technology has allowed for the development of capacitive dyes removal (CDR) methods using ES devices. In our study, porous carbon materials, N-doped activated carbon coated MWCNT (N-AC-MWCNT) and N-doped activated carbon nano-fibers (N-AC-NF), were developed as the electrodes for CDR applications. The experimental results indicated that capacitive performance of ES cells was influenced by the chemical structure, size, charge-to mass ratio, concentration and redox-active ligands of the dyes. CDR is a promising method for removal of various cationic and anionic dyes, which offers advantages of energy saving and simple electrode regeneration. / Thesis / Doctor of Philosophy (PhD)

Polymer coatings are thin films of polymer deposited on different substrates for various applications. Such surface coatings can serve a functional purpose (adhesives, photographic films), protective purpose (anticorrosion), or decorative purpose (paint). Additionally, their composite coatings containing ceramic, or metal particles are often used to enhance durability, functionality, or aesthetics. Electrophoretic deposition (EPD) and dip coating are two promising methods for the fabrication of polymer and composite coatings due to the ease of fabrication, low cost, and high-volume production. EPD involves the electrophoresis of charged particles and their deposition on the electrode surface, which requires the colloidal particles to be charged in a stable suspension as a precursor solution for deposition. Many polymers cannot be deposited by EPD directly because of their charge neutrality and poor dispersion. Therefore, it is critical to develop efficient charging dispersants to modify electrically neutral polymers for their EPD. The approach was inspired by the strong solubilization power of bile acids in the human body. Two types of bile salts, cholic acid sodium salt and sodium chenodeoxycholate, and three types of biosurfactants, carbenoxolone sodium salt, glycyrrhizic acid, and 18β-glycyrrhetinic acid, which share similar structures with bile salts, were discovered for charging, dispersion, and EPD of different materials. The electrically neutral polymers (PTFE and PVDF), chemically inert materials (diamond, nanodiamond, graphene, carbon dots, carbon nanotubes and Zr-doped hydrotalcite (MHT)), and their composites can be well dispersed in suspension and deposited using these bio-surfactants as dispersants. It was found that the unique chemical structures of these biomolecules play vital roles in the surface modification and EPD of different materials. Moreover, the deposited polymer (PVDF, PTFE) and composite (PTFE-MHT) coatings can provide outstanding corrosion protection for stainless steel. The biomimetic and versatile strategy opens a way for the deposition of other electrically neutral materials through EPD. These findings also provide a promising strategy for selecting new dispersants for EPD. The deposition of high molecular weight (MW) polymers such as poly(ethyl methacrylate) (PEMA) at high concentrations in non-toxic solvents continues to be a challenge for dip coating. In this work, we firstly proposed using water-isopropanol as a co-solvent to dissolve high MW PEMA at high concentrations. It was found that water molecules can solvate carbonyl groups of PEMA and facilitate their dissolution. This method avoided the usage of toxic solvents and a long-time heating procedure for their removal. Moreover, it allows the fabrication of high-quality PEMA and composite coatings containing different flame retardant materials (FRMs), including double hydroxide LiAl2(OH)7.2H2O (LiAlDH), huntite, halloysite and hydrotalcite, through the dip coating method. A novel solid state synthesis method was proposed to fabricate LiAlDH, which is promising for the fabrication of other advanced DHs. Such composite coatings combined advanced properties of PEMA and functional properties of FRMs, such as corrosion inhibition and FR properties. / Thesis / Doctor of Engineering (DEng) / Polymer and composite coatings have been utilized for a wide range of applications due to their barrier properties, scratch and abrasion resistance, chemical resistance, and biocompatibility. Various techniques have been developed to fabricate polymer and composite coatings, such as electrophoretic deposition (EPD) and the dip coating method. However, limitations remain. EPD unitizes an electrical field to drive charged particles in a suspension toward conductive substrates to achieve film deposition. This process requires a stable suspension with charged particles, therefore, the electroneutral polymers present difficulties in their EPD. In addition, dissolving high molecular weight polymers at high concentrations in a non-toxic solvent is currently challenging, which is vital to utilize dip coating technique. The objective of this work was to develop advanced charging dispersants for EPD of electroneutral polymers and non-toxic solvents for dip coating of high molecular weight polymers. New biomimetic and versatile approaches have been developed for EPD of different electrically neutral polymers, chemically inert materials, and their composite coatings. A non-toxic co-solvent was proposed to dissolve high molecular weight polymer at high concentration for dip coating of the polymer and its composite coatings containing flame retardant materials. The results presented in this work showed the formation of high-quality films with multifunctionality and paved new strategies for further developments.

<p>Electrochemical deposition methods have been developed for the fabrication of organic － inorganic nanocomposite coatings. The methods are based on electrophoretic deposition of ceramic nanoparticles and polymers.</p> <p>EPD method has been developed for the deposition of nanostructured TiO₂ films using new dispersing agents. The stabilization and charging of the nanoparticles in suspensions was achieved using these organic molecules, which belong to catecholate and salicylate families. Anodic deposition was achieved using caffeic acid, 2,3－dihydroxybenzoic acid, 2,6－dihydroxybenzoic acid and 5－sulfosalicylic acid. Cathodic deposition was performed using 2,4 dihydroxycinnamic acid, p－coumaric acid and trans cinnamic acid. The deposition yield has been studied as a function of the additive concentration and deposition time. The deposition mechanism has been investigated. The fundamental adsorption mechanism is based on the complexation of metal ions at the surfaces of oxide nanoparticles. The method enabled the co-deposition of TiO₂ and other oxides and the formation of composite films.</p> <p>Electrophoretic deposition method has been used for the deposition of TiO₂ nanoparticles modified with organic dyes. Alizarin red, alizarin yellow, pyrocatechol violet and Aurintricarboxylic acid dyes were used for the dispersion and charging of TiO₂. The microstructures of the nanocomposite coatings were studied. The deposition yield was investigated under a variety of conditions. Obtained results could pave the way for the fabrication of dye-sensitized TiO₂ films.</p> <p>EPD method has also been developed for the fabrication of (Poly[3-(3-N,N-diethylaminopropoxy)thiophene]) PDAOT－TiO₂, (polyethylenimine) PEI－TiO₂ and PEI－hydrotalcite composite films. The microstructures of the nanocomposite coatings were studied by Scanning Electron Microscopy, Thermogravimetric Analysis, which showed the co－deposition of inorganic nanoparticles and organic polymer. Electrochemical test of the composite film has been conducted. The results showed that PEI film provided corrosion protection of the stainless steel substrates.</p> / Master of Science (MSc)

<p>Electrochemical methods show great promise in the deposition of biocompatible coatings for biomedical applications with advanced functionality. Consequently, methods of creating coatings of bioactive materials, such as halloysite nanotubes (HNT), hydroxyapatite (HA), chitosan, hyaluronic acid (HYH), poly-L-ornithine (PLO) and poly-L-lysine (PLL) and polyacrylic acid (PAA) have been developed through the use of electrophoretic deposition (EPD). The co-deposition of these materials are achieved at voltages ranging from 5 to 20 V on a 304 stainless steel substrate using suspensions of 0.5 and 1.0 gL^-1 biopolymer (chitosan, PAA, PLO, PLL) containing 0.3, 0.5 0.6, 1.0 and 2.0 gL^-1 bioceramic (HNT, HA). The resulting films were then investigated to further understand the kinetics and mechanics of deposition, determine their properties, and evaluate their suitability for physiological applications. The films were studied using X-Ray Diffraction (XRD), Differential Thermal Analysis and Thermogravimetric Analysis (DTA/TGA), Scanning Electron Microscopy (SEM), Quartz Crystal Microbalance (QCM) and Linear Polarisation. The results indicate that film thickness, composition and morphology can be controlled and modified at will, and that the deposition of composite films, multilayer laminates and functionally graded films are possible.</p> / Master of Applied Science (MASc)

Electrochemical supercapacitors (ESs) have attracted great attention due to the advantages of long cycle life, high charge/discharge rate and high power density compared to batteries. Significant improvement in ES performance has been achieved via development of advanced nanostructured materials, such as MnO2 and composite MnO2-MWCNT and PPy-MWCNT electrodes. In this dissertation, advanced dispersants were developed and investigated for the dispersion, surface modification and electrophoretic deposition (EPD) of metal oxides, multiwalled carbon nanotubes (MWCNT) and polypyrrole (PPy) in different solvents. Nature-inspired strategies have been developed for the fabrication of MWCNT films and composites. The outstanding colloidal stability of MWCNT, dispersed using anionic bile acids, allowed the EPD of MWCNT. Composite MnO2-MWCNT films were obtained by anodic EPD on Ni plaque and Ni foam substrates. Good dispersion of MWCNT during Py polymerization was achieved and allowed the formation of PPy coated MWCNT. The film and bulk electrodes, prepared by EPD and slurry impregnation methods, respectively, showed high capacitance and good capacitance retention at high charge-discharge rates. The mechanisms of dispersion and deposition were investigated. Cathodic and anodic EPD of MWCNT, MnO2, Mn3O4 was achieved using positively and negatively charged dispersants. Co-deposition of MWCNT and MnO2 was performed using a co-dispersant, which dispersed both MWCNT and MnO2 in ethanol. Composite films were tested for ES applications. The efficient dispersion was achieved at relatively low dispersant concentrations due to strong adsorption of the dispersants on the particle surface, which involved the polydentate bonding. We found the possibility of efficient dispersion of MWCNT in ethanol using efficient anionic dispersants. The electrostatic assembly method has been developed, which offers the benefit of improved mixing of MnO2 and MWCNT. The use of different anionic and cationic dispersants allowed the fabrication of electrodes with enhanced capacitance and improved capacitance retention at high charge–discharge rates and high active mass loadings. The asymmetric devices, containing positive MnO2–MWCNT and negative AC–CB electrodes showed promising performance in a voltage window of 1.6 V. We proposed another novel concept based on electrostatic heterocoagulation of Mn3O4- MWCNT composites in aqueous environment. In this case, various dispersants were selected for adsorption and dispersion of MWCNT and Mn3O4 and this allowed the formation of stable aqueous suspensions of positively charged MWCNT and negatively charged Mn3O4, which facilitated the formation of advanced composites with improved mixing of the components. Testing results showed promising performance of Mn3O4–MWCNT composites for applications in electrodes of electrochemical supercapacitors. / Thesis / Doctor of Philosophy (PhD)

<p> New electrophoretic deposition methods for the fabrication of advanced organic-inorganic composite coatings on metallic substrates for biomedical applications have been developed. In the proposed methods, chitosan was used as a matrix for the fabrication of multilayer and functional graded chitosan- hydroxyapatite (HA) coatings. The HA particles showed preferred orientation of c-axis parallel to the layer surface, which is similar to the bone structure. Electrochemical studies showed that the obtained coatings provided corrosion protection of the metallic substrates, such as stainless steel and Nitinol.</p> <p> The feasibility of co-deposition of chitosan and heparin has been demonstrated. Composite chitosan-heparin layers were used for the surface modification of chitosan-HA coatings. Obtained results paved the way for the electrophoretic fabrication of novel coatings for biomedical implants with improved blood compatibility.</p> <p> The feasibility of co-deposition of hyaluronic acid and HA has also been demonstrated. The co-deposition of hyaluronic acid and HA resulted in the fabrication of novel nanocomposite films by electrodeposition. The chemical composition, microstructure, corrosion protection, and other functional properties of the nanocomposites have been investigated. Co-deposition of hyaluronic acid and multiwalled carbon nanotubes has been studied by TGA/DT A and SEM studies.</p> <p> The feasibility of deposition of novel composites based on alginic acid has been demonstrated. New electrochemical strategies were used for the fabrication of alginic acid-HA, alginic acid-heparin and alginic acid -hyaluronic acid nanocomposites. The composition of these nanocomposite coatings can be varied by variation in bath composition for EPD.</p> <p> The electrochemical mechanisms for the fabrication of all these advanced organic-inorganic composite coatings have been developed.</p> / Thesis / Master of Applied Science (MASc)

Dans le secteur aéronautique en pleine expansion, les préoccupations environnementales prennent une place de plus en plus importante. Les motoristes recherchent des solutions innovantes pour augmenter les rendements tout en diminuant les coûts. Dans cette perspective, de nouveaux systèmes de barrières thermiques synthétisés par la voie sol-gel à partir de poudres commerciales, de céramiques avec différents facteurs de forme et d'agents porogènes ont été mis en œuvre et évalués. Certains systèmes présentent une durée de vie de plus de 1000 cycles en oxydation cyclique. Malgré tout, cet accroissement des températures de fonctionnement des moteurs, induit une élévation des températures de surfaces des barrières thermiques et peut générer de nouvelles dégradations du système complet : la corrosion à hautes températures par les CMAS. Pour pallier ces inconvénients, il est possible de développer des revêtements anti-CMAS, susceptibles de réagir avec les composés CMAS avant qu'ils n'aient un effet néfaste sur l'intégrité de la barrière thermique. Dans cette étude, nous nous sommes intéressés particulièrement aux revêtements sacrificiels anti-CMAS à base d'yttrine et de systèmes pyrochlore, qui ont été testés sur des barrières thermiques industrielles de type EBPVD. Par ailleurs, les procédés que nous avons développés, basés sur la voie sol-gel, nous permettent, de par leur facilité de mise en œuvre, d'envisager des perspectives prometteuses en termes de réparabilité des barrières thermiques endommagées. En effet, compte tenu du coût élevé de fabrication des pièces, les aubes devraient être réparées plusieurs fois avant d'être mises au rebut. Dans ce travail, un procédé de mise en forme a été évalué dans ce sens. Il s'agit de l'électrophorèse qui est une technique bien adaptée au dépôt sur pièces complexes. L'objectif de ces investigations a donc été double : tout d'abord créer de nouveaux systèmes de barrières thermiques avec des propriétés anti-CMAS par électrophorèse puis réparer les barrières thermiques EBPVD endommagées et leur déposer une couche protectrice anti-CMAS par ce même procédé. Cet aspect " procédé " sera abordé en dernière partie de ces travaux. / In the aeronautics sector, environmental concerns are becoming increasingly important. Engine manufacturers are looking for innovative solutions to increase efficiency while lowering costs. The objective is to optimize thermal conductivity and durability with the cyclic oxidation resistance. In this perspective, new thermal barrier systems synthesized by the sol-gel route from commercial powders, ceramics with various form factors and pore-forming agents have been implemented and evaluated. Some systems are a lifetime higher than 1000 cycles in cyclic oxidation. However, this increase in the operating temperatures of the engines induces an increase in the temperature of the surfaces of the thermal barriers and can generate further degradations of the complete system: the corrosion by CMAS. To overcome these disadvantages, it is possible to develop anti-CMAS coatings capable of reacting with CMAS compounds before they have a detrimental effect on the integrity of the thermal barrier. In this study, we were particularly interested in anti-CMAS protective coatings based on yttria and pyrochlore systems, which were tested on industrial thermal barriers realized by EBPVD. Moreover, the processes we have developed, based on the sol-gel path, allow us, because of their ease of implementation, to envisage promising prospects in terms of repair of damaged thermal barriers. Indeed, given the high cost of manufacturing parts, the blades should be repaired several times before being discarded. In this work, a shaping process has been evaluated in this direction. This is electrophoretic deposition which is a technique allowing to deposit on complex parts. The objective of these investigations was therefore twofold: firstly to create new thermal barrier systems with anti-CMAS properties by electrophoretic deposition and then to repair the damaged EBPVD thermal barriers and to deposit an anti-CMAS protective layer by this same process. This "process" aspect will be discussed at the end of this work.

Grâce à son faible coût, sa grande résolution et son absence d’effet ionisant, l’imagerie ultrasonore haute fréquence est devenue une technique usuelle pour les applications médicales telles que l’imagerie de l’œil, de la peau ou du petit animal. Cette méthode repose sur la capacité de matériaux piézoélectriques à créer des ondes acoustiques hautes fréquences dans les tissus à explorer. Les dispositifs qui opèrent ces conversions électromécaniques sont appelés transducteurs ultrasonores et doivent délivrer des fréquences de résonance de plus de 20 MHz, nécessitant l’intégration des films piézoélectriques ayant une épaisseur de quelques dizaines de micromètres. La fabrication de tels matériaux pour les transducteurs mono- et multi-éléments est toujours difficile suivant les procédés choisis. Dans ce manuscrit, le procédé de dépôt par électrophorèse a été étudié. Il permet le dépôt de films épais sur de nombreux substrats de formes complexes en vue de la fabrication de transducteurs hautes fréquences. Dans cette thèse, il est clairement montré que l’électrophorèse est un procédé simple prometteur et performant pour préparer des films épais homogènes sans défaut avec des propriétés fonctionnelles élevées pour la réalisation de transducteurs hautes fréquences (40 MHz). / Thanks to its relatively low cost, high resolution and absence of ionizing radiations, high frequency ultrasonic imaging is becoming a popular technique for medical applications such as eyes, skin or small animal. It relies on the ability of piezoelectric materials to generate high frequency ultrasonic waves in the scanned media. Ultrasonic transducers are used to perform these electromechanical conversions and operated at resonant frequencies over 20 MHz. For this, piezoelectric layers of few tens of micrometers thick are required. Such thicknesses for single element transducers, and even more for multi-element transducers, is difficult to deliver due to limitations of current fabrication process. In the present dissertation we addressed the electrophoretic deposition (EPD) technique that enables deposition of piezoelectric thick films on various complex-shaped substrates. A procedure to prepare high frequency transducers by EPD was developed. In the dissertation it was demonstrated that EPD is a promising process to prepare homogeneous thick-film structures without significant defects. The procedure allowed obtaining high electromechanical performance transducers using a simple and low cost process.

Made available in DSpace on 2015-03-26T13:35:12Z (GMT). No. of bitstreams: 1 texto completo.pdf: 6352723 bytes, checksum: a4c7f969c677c4ff29babce9dae7052c (MD5) Previous issue date: 2009-07-13 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / In this study, films of carbon nanotubes (CNT) on substrates of stainless steel, aluminum, silicon and Nafion® were prepared using the technique of Electrophoretic Deposition (EPD). The films produced were characterized by Scanning Electron Microscopy (SEM). In all deposition experiments, the higher the applied potential, the higher was the deposition rate. Concomitantly to the EPD occurred electrolysis of the solvent, generating a significant electric current through the cell and gas bubbles on the surfaces of the electrodes. The depositions was only possible with potential higher than 20V. In experiments using only pure solvent and working electrode with carbon nanotubes deposited, the measured values of the density of electric current was always higher than the values measured using the electrode without CNT deposited, showing that the addition of CNT on the surface substantially increases the effective reactivity of such electrodes. The images of SEM showed that EPD in suspensions of functionalized CNT in water, on stainless steel and Nafion®, produced uniform, homogeneous and compact CNT films and that the carbon nanotubes deposited are long, up to about 5 &#956;m in length. During the electrophoretic deposition on stainless steel, in suspensions prepared with material the "as grown" in acetone, the measured electric current grows with increasing concentration of iodine additioned in the suspension. When the concentration of iodine was less than or equal to 0,5 mg/ml the deposit was not homogeneous. In EPD in suspensions of non-functionalized CNT dispersed in DMF steel, aluminum and silicon were used as substrates. In this type of suspension, the absolute values of the initial electric current and the electric current of saturation were higher than the values observed in tests in acetone. One explanation for this would be the difference in the amount of water dissolved in the two solvents. The characterization by SEM showed that, in this type of suspension in DMF, carbon nanotubes films produced are also uniform and homogeneous, but less compact than the films produced with the functionalized nanotubes. The non-functionalized CNT are much longer that the functionalized, reaching about 60 &#956;m in length, which can hinder compaction of the film. Probably, these carbon nanotubes are longer because they have not suffered chemical attacks used in the purification and functionalization processes. / Neste trabalho, foram preparados filmes de Nanotubos de Carbono (CNT Carbon Nanotubes) sobre substratos de aço inox, alumínio, Nafion® e silício utilizando a técnica de Deposição Eletroforética (EPD Electrophoretic Deposition). Os filmes produzidos foram caracterizados através de Microscopia Eletrônica de Varredura (MEV). Em todas as deposições realizadas, quanto maior o potencial aplicado, maior foi a taxa de deposição. Concomitante às EPD s ocorreu a eletrólise do solvente, gerando uma corrente significativa através da célula e bolhas de gás sobre as superfícies dos eletrodos. Só foi possível deposições com potenciais acima de 20 V. Nos experimentos empregando-se somente solvente puro e utilizando-se o eletrodo de trabalho com nanotubos de carbono depositados, os valores de corrente medidos foram sempre mais elevados que os medidos utilizando-se o eletrodo sem CNT depositado, demonstrando que a adição de CNT à superfície aumenta substancialmente a reatividade efetiva de tais eletrodos. As imagens de MEV mostraram que as EPD s em suspensões de CNT s funcionalizados em água, sobre aço inox e Nafion®, produziram filmes de CNT s uniformes, homogêneos e compactos e que os CNT s depositados são longos, podendo atingir cerca de 5 &#956;m de comprimento. Durante as deposições eletroforéticas sobre aço inox, em suspensões preparadas com material as grown em acetona, as correntes medidas através da célula crescem com o aumento da concentração de iodo adicionada à suspensão. Quando a concentração de iodo foi igual ou inferior a 0,5 mg/ml o depósito produzido não foi homogêneo. Nas EPD s em suspensão de CNT s não-funcionalizado dispersos em DMF utilizou-se o aço inox, alumínio e silício como substratos. Neste tipo de suspensão, os valores absolutos da corrente inicial e de saturação foram mais elevados que os observados nos ensaios em acetona. Uma explicação para este fato seria a diferença de quantidade de água dissolvida nos dois solventes. A caracterização via MEV mostrou que neste tipo de suspensão em DMF os filmes de nanotubos de carbono produzidos via EPD são igualmente uniformes e homogêneos, porém, menos compactos que os filmes produzidos com os nanotubos funcionalizados. Os CNT s não-funcionalizados são muito mais longos que os funcionalizados, podendo atingir cerca de 60 &#956;m de comprimento, o que pode dificultar a compactação do filme. Provavelmente, esses nanotubos de carbono são mais longos porque não sofreram ataques químicos utilizados no processo de purificação e funcionalização.