Ce travail de thèse s'inscrit dans le contexte de la fonctionnalisation de matériaux cellulosiques dans le domaine de l'électronique imprimée. Une première approche a mis en évidence la possibilité d'imprimer des formulations aqueuses à base de nanoparticules de polymères semi-conducteurs photoluminescents. L'influence de la taille des nanoparticules, ainsi que leur composition (ajout d'un polymère dérive de la cellulose) sur la couleur de l'émission a été mise en évidence. Les applications potentielles peuvent être l'élaboration de papiers sécurisés. Une seconde approche s'est portée sur l'utilisation de microfibrilles de cellulose et de microparticules de cuivre afin d'élaborer des films composites conducteurs autoportants grâce aux excellentes propriétés mécaniques des microfibrilles. L'influence d'un calandrage (pression et température de calandrage) des films sur la conductivité électrique a en particulier été étudiée. / The context of this project is the cellulosic material functionalization in the printed electronic domain. The first part highlighted the ability to print photoluminescent formulations. The aqueous dispersion was composed of semiconducting polymer nanoparticles. The influence of the size and the composition of the particles on the emission colour was studied. Security paper is one of the main potential application of these particles. The second part dealed with the use of cellulose microfibrills and copper microparticles for the elaboration of conductive composite films. The films were self-supporting thanks to the high mechanical properties of the microfibrills. A calendering study was carried out on the electric conductivity of the films based on the influence of the pressure and the temperature of calendering.

Made available in DSpace on 2016-06-02T20:16:43Z (GMT). No. of bitstreams: 1 1994.pdf: 1761798 bytes, checksum: 183ce1c471cf1079a1302b309c923a68 (MD5) Previous issue date: 2002-04-11 / Financiadora de Estudos e Projetos / In the present work the Drude weight is calculated to study the capacity of conduction at finite temperatures in one-dimensional rings with the potencial given by the sequences of different degrees of randomness and threaded by a time independent magnetic flux. In this context, the tight-binding approximation is used to solve the Schrödinger equation,also permitting the potencials, given by substitution sequences, to be implemented in a simple way. We study four situations in which the potencial is given by periodic and random sequence. The transport properties exhibited by the system in each case are to reflect the degree of randomness presented by these potencials, although in a nontrivial manner if one considers a hierarchy of disorder based on the Fourier transform of the sequences. The role played by temperature in the capacity of conduction, as compared with the role played by the potencials, is also described. / No presente trabalho, através do cálculo do peso de Drude estudamos a capacidade de condução a temperaturas finitas, em anéis unidimensionais com potenciais dados por seqüências de diferentes graus de desordem e atravessados por fluxo magnético independente do tempo. Neste contexto, utilizamos o modelo tight-binding na resolução da equação de Schrödinger, o que permite inserir os potenciais, dados por seqüências de substituição, de maneira simples. Estudamos quatro casos em que esse potencial seja dado por seqüências não periódicas. Os resultados são comparados com os dois casos limites de organização, a saber, as seqüências periódica e desordenada. Observa-se que o grau de desordem apresentado por estes potenciais reflete-se nas propriedades de transporte exibidas pelo sistema em cada caso, embora de maneira não trivial se considerada uma hierarquia de desordem baseada na transformada de Fourier das seqüências. Descreve-se também a influência da temperatura, frente à influência dos potenciais, na capacidade de condução.