No description available.

Organic acids are usually the reactants which proceed in chlorination reaction into products of disinfection by-products in water treatment plant. The purpose of this study is by using tests of kinetics and equilibrium adsorptions to investigate adsorption characteristics and kinetic model evaluations of selected organic acid in solution. We use commercial carbon nano-tube for the adsorbents. The major factors in adsorption tests include the concentration of fulvic acid (a typical organic acid in raw water), pH, ionic strength and temperature. Experiment results exhibited kinetic adsorption reached equilibrium about 120 minutes, the adsorption capacity increased with concentrations increasing of fulvic acid and decreased with ionic strengths. The best selection in kinetic models evaluation, fitting models such as Modified Freundlich equation, Pseudo-1st-order equation and Pesudo-2nd-oder equation is Modified Freundlch equation model. In addition, intraparticle diffusion equation model was fitted well and showed adsorption process was controlled with pore diffusion. The maximum adsorption capacity varied from 26.094 to 20.772 mg/g when temperature ranging from 4 to 45¢J. Isotherm adsorption results were fitted on Langmuir and Freundich models. The £GG¢X values ranged from -0.930 to -1.014 kcal/mol, £GH¢X:-1.561 kcal/mol and £GS¢X:-2.02 cal/mol. Thermodynamic parameters indicated that the adsorption is spontaneously and an exothermic reaction. Adsorption of fulvic acid by carbon nano-tube has a good performance when operation conditions of higher fulvic acid concentration, lower ionic strength, lower pH and lower temperature.

L'effet photovoltaïque est une des voies qui s'est significativement développée au cours des dernières années afin de trouver une alternative à la production d'énergies non-renouvelables. Afin de diminuer le coût de fabrication de ces dispositifs photovoltaïques, une solution consiste à remplacer le silicium par des matériaux organiques. Les cellules solaires organiques sont une technologie en pleine émergence qui ambitionne la fourniture de cellules solaires plus flexibles dans tous les sens du terme : mécanique, fabrication, propriétés électro-optiques. Un défi auquel la recherche est confrontée aujourd'hui est l'obtention de matériaux organiques stables et solubles qui absorbent aux longueurs d'ondes du proche infrarouge. Ce travail de thèse réalisé dans l'Équipe de Recherche Technologique CSPVP de l'Université d'Angers a pour objectif de relever le défi. La première partie de notre travail est consacrée à l'utilisation de nouveaux dérivés de fullerènes. Afin d'améliorer l'absorption du fullerène C60 ou/et de chercher de possibles alternatives au PCBM, des nouveaux composés ont été synthétisés. Ces nouveaux dérivés peuvent être répartis en: dyades C60-PDI(R=OPhtBu, Cl), cyclopropano[60]fullerènes et cyclopropano[70]fullerènes de type Bingel porteurs de deux groupes esters C60(ou 70)>(CO2R1)(CO2R2), et l'adduit-1,4 C60(CH2CO2tC4H9)2. Ces dérivés de fullerènes ont été incorporés dans les couches photo-actives des cellules solaires à base du polymère conjugué poly(3-hexylthiophène) (P3HT), en tant que matériau de type accepteur. Tous ont été utilisés en cellules solaires pour lesquelles nous avons cherché à préciser la relation entre structure moléculaire et performances photovoltaïques via la morphologie de la couche active. Des études supplémentaires ont été effectuées afin de corroborer les résultats photovoltaïques (PV) avec les propriétés physico-chimiques des matériaux. La deuxième partie est consacrée à des études physico-chimiques réalisées sur des différents nanotubes de carbones mono-feuillets (SWCNT) fonctionnalisés par des groupements esters. Ces nanotubes fonctionnalisés présentent une meilleure dispersion dans les solvants organiques. Ils ont été étudiés et comparés à différentes concentrations dans des cellules solaires à base de P3HT :PCBM. Des travaux complémentaires ont été effectués sur des dérivés de poly(phénylène vinylène) (PPV) et des dérivés de polythiophène, et des cellules élaborées à partir de dérivés de carbazole attaché sur le noyau de C60 et déposés sur des substrats ITO/PEDOT :PSS par électropolymérisation. En conclusion, nous passons en revue les paramètres qui contribuent directement aux performances photovoltaïques des cellules étudiées.

This thesis research investigates the adhesion mechanisms of protein molecules to surfaces of biomaterials. New understanding in such adhesion mechanisms will lead to materials design and surface engineering in order to extend the lifespan of implants. The present research evaluates and analyzes the adhesive strength of proteins on pure High Density Polyethylene (HDPE), Single Wall Carbon Nanotube (SWCNT) enhanced HDPE composites, Ti-C:H coating and Ti6Al4V alloys (grade 2). The adhesive strength was studied through fluid shear stress and the interactions between the fluid and material surfaces. The adhesive strength of protein molecules was measured through the critical shear strength that resulted through the fluid shear stress. The effects of surface and material properties, such as roughness, topography, contact angle, surface conductivity, and concentration of carbon nanotubes on adhesion were analyzed. Research results showed that the surface roughness dominated the adhesion. Protein was sensitive to micro-scale surface roughness and especially favored the nano-porous surface feature. Results indicated that the unpurified SWCNTs influenced crystallization of HDPE and resulted in a nano-porous structure, which enhanced the adhesion of the protein onto a surface. Titanium hydrocarbon coating on silicon substrate also had a porous topography which enhanced its adhesion with protein, making it superior to Ti6Al4V.

No description available.

<p>Polymer based multifunctional material systems (MFMS) have gained increasing attention in the past two decades. The addition of nanofillers and nanoparticles allows for modification of physical properties as well as the discovery of new features. Multifunctionalization of composites allows us to “do more with less”. For example, electrically conductive additives can eliminate the need for sensors through self-sensing principles, shape morphing matrices can reduce the need for actuators, and the inclusion of fire-resistant constituents can reduce flammability in stringent fire protection measures. With added capabilities, the applications of multifunctional composites extends beyond the aerospace and automotive industries to healthcare, infrastructure, electronics, among others, and optics.</p> <p><br></p> <p>The current state of the art is largely focused on single-filler composites or multifiller composites with complementary attributes. For example, carbon nanotubes (CNTs) when mixed with graphene produces higher conductivity than can be achieved via modification with either CNTs or graphene alone. The majority of investigations conducted in this domain have fillers selected with the aim of imparting a singular property. Much less has been done in the area of multifiller and multifunctional polymer matrix composites (PMCs) which can exhibit multiple properties. Consequently, this work seeks to contribute towards the field of synergistic functional composites. That is, a multifiller composite material system comprised of differently functional fillers. This approach has potential to yield smart material systems that outperform single-filler or single-functionality materials through the discovery of novel synergistic coupling between the differently functional phases.</p> <p><br></p> <p>In light of the preceding motivation, this work presents the results on the experimental electromagnetic and mechanical characterization of multi-walled carbon nanotubes (MWCNTs) + carbon-coated iron nanoparticle (CCFeNP)-modified polymers. Carbon nanotubes with their electrical properties and iron nanoparticles with their magnetic attributes present potential for synergistic electromagnetic interactions in a well-percolated network. We report on the electro-magnetic properties of MWCNT + CCFeNP/epoxy composites including DC and AC conductivity, dielectric permittivity, magnetic permeability, and piezoresistance as a function of varying relative MWCNT and CCFeNP concentrations. The results are in a large part linked to the manufacturing process described herein. This work seeks to establish the foundations of synergistic functional filler combinations that could lead to new multifunctional capabilities in the future.</p>

No description available.

Carbon nano tubes (CNT’s) are promising candidates for several sensor applications such as optical sensors, strain gauges or flow sensors. For certain sensor structures liquid CNT dispersions are required. These are important not only for the realization of CNT-films for sensors like strain gauges but also for technological processes such as dielectrophoresis. CNT-films are realized by deposing the dispersion on a carrier material followed by a drying process. The dispersion properties depend on several parameters like CNT concentration, surfactant concentration, sonication time, centrifugation time, storing time and other parameters. Methods for characterization of dispersions are up to now limited to UV/VIS spectroscopy. This is generally limited to low CNT concentrations. This paper discusses the possibility to use impedance spectroscopy as characterization method for the stability of the dispersions. The impedance of the dispersion was measured using a conductivity measurement cell with platinum electrodes. The behavior of characteristic points of the impedance spectrum was investigated for three identically prepared samples during 7 days of storing time. The systematic trend observed is definitively larger than the variance between different samples. With increasing time after preparation the CNT fallout will increase and the amount of deposable CNT’s will decrease. The decreasing imaginary part indicates an easier diffusion of surfactant molecules because they are not longer attached to CNT’s.

No description available.

Ayant une structure particulière avec une tête hydrophile et une queue hydrophobe, des molécules amphiphile ont de nombreuses applications importantes, comme par exemple, la fabrication des détergents, la protection et la fonctionnalisation de surfaces, etc. Des agrégats de diverses formes, micelles, véhicules, membranes etc., peuvent se former à partir des amphiphiles. La complexité de ces agrégats moléculaires rend l’étude théorique de ce type de systèmes extrêmement difficile. Jusqu’à présent, notre connaissance sur l’interaction entre des nanoparticules et des agrégats des amphiphiles reste encore incomplète. A l’aide de certaines méthodes de simulations moléculaire et une approche théorique, nous avons entrepris une série d’études pour mieux comprendre les questions fondamentales suivantes :1. Comment la présence de nanoparticules, notamment la courbure de ses surfaces, affecte l’agrégation de molécules amphiphile ?2. Comment une bicouche de lipide, une forme d’agrégat particulier des amphiphile, peut induire l’assemblage auto-organisé de nanoparticules hydrophobes ?3. Est-ce que la présence des nanoparticules peut provoquer des transitions morphologiques d’un nanotube membranaire ? / Amphiphile molecules, endowed with a particular structure containing a hydrophilic head and a hydrophobic tail, have many important applications, e.g., fabrication of detergents, surface coating or surface functionalization, etc. Molecular aggregates of various forms, micelles, vehicle, membranes, etc. can be formed from amphiphile molecules. The complexity of these molecular aggregates involving a large number of atoms make the theoretical study of these system very challenging. Up to now, our understanding of the interaction between nanoparticles and aggregates of amphiphiles remains quite incomplete. Using a variety of molecular simulation methods and some theoretical approaches (Helfrich theory and perturbation theory), we have studied the following issues in the present thesis: 1. How the presence of nanoparticles, especially due to their highly curved surfaces, affects the aggregation of the amphiphiles? 2. How a lipid bilayer, a particular amphiphile aggregate, induces the self-assembly of hydrophobic nanoparticles.3. How the morphology transition of a membrane nanotube can be induced by nanoparticles?