Data/hora: 20/06/2024 21:07:34

Biblioteca(s): | Embrapa Instrumentação.
Data corrente: | 22/12/1999
Data da última atualização: | 23/02/2012
Autoria: | MATTOSO, L. H. C.; OLIVEIRA JUNIOR, O. N.; FERREIRA, M.
Afiliação: | EMBRAPA-CNPDIA; USP-IFSC.
Título: | Conducting polymers (for Langmuir-Blodgett film fabrication).
Ano de publicação: | 1996
Fonte/Imprenta: | In: SALAMONE, J.C. (Ed.). Polymeric materials encyclopedia. Boca Raton: CRC, 1996.
Páginas: | p. 1432-1439.
Idioma: | Inglês
Conteúdo: | There has been considerable excitement recently over the use of conducting polymers in a variety of technological applications. Some of the applications have already been commercialized, as in the case of rechargeable batteries, conductive textiles, and electrical display. Sophisticated long-term applications are also envisaged for these materials, including the fabrication of molecular electronics devices, that is, devices in which switching and memory phenomena would be controlled at the molecular level. Two main requiremos must be met to achieve such an ambitious goal. First development of the ability to construct structures whouse molecular architecture could be manipulated and appropriately designed. Such structures are most likely to consist of ultra-thin films. Two techniques are available for this purpose, namely the Langmuir-Blodgett (LB) method, which has been investigated extensively for several yearls, and the more recent Self Assembly (SA) technique for building multilayers. These techniques allow the fabrication of ultra-thim (of the order of nm) in the form of multilayers with a high degree of control of orientational order in the case of the LB films, The second requirement concerns the acess to individual molecules. Though substantial research must be carried out before this requirement can be met, the progesss reported in the use of atomic force microscopy (AFM) and scanning tunneling microscopy (STM) on molecular system is most encouraging. It is now possible to image monolayers of simple molecules on graphite and also to probe and manipulate individual molecules at surfaces. We are concerneed with the first of the above-mentioned aspects, focusing on the LB technique that has been exploited worldwide for fabricating ultra-thim films of a variety of materials, including conducting polymers. Because the formation of LB films requires the spreading of a monolayer onto an aqueous subphase, some prerequisites must be fulfilled by the material of interest. It must be soluble in a reasonably volatile organic solvent and also sufficiently surface for spreading to occur. The conducting polymers that were first investigated, namely polyacetylene, polypyrrole, polythiophene, and polyaniline, could not be processed in this manner, and therefore several atrategies were developed for overcoming this difficulty. An overview of these strategies will be provided below, following a brief introduction to LB films. Recent developments on the LB films from polyanilines will then be discussed, followed by a description of the most important properties and some of the possible appications that have been demonstrated for LB films of conducting polymers.
Palavras-Chave: | Polimeros.
Categoria do assunto: | --
Registro original: | Embrapa Instrumentação (CNPDIA)
Exemplares: | CNPDIA - (5625-1) - UPC - SP - -- - PROCI-96.00136 -  - 1996.00136 - DIS