Ceramic and hybrid nanomaterials prepared by the sol-gel process

Abstract

This proposal for thematic research involves a group composed by five principal researchers and two young P.H.D., including also post graduated, graduated and under graduated students. The principal aim of this proposal is to keep and deepen the studies we have been developing since five years ago, on the preparation of ceramic or hybrid materials by using the sol-gel process. The subject-matter of this proposal involves the study of thin layers, which can behaves as foams and membranes for ultrafiltration, anti-corrosion coatings, electrochromic materials, wave guides, transparent and ionic or electronic conducting films, that can be applied in optical, electro-optical and photoelectrochemical devices, prepared from chemical processes. All of these systems present a common point: the nanometrical characteristics of phases or domains, that are responsible by the specific properties associated to the postulated applications. In the case of ceramic-polymer nanocomposites, we propose the preparation of a siloxane-organic polymer (polyetyleneoglycol, PEG, e polypropylenoglycol, PPG) hybrid compounds presenting covalent chemical bonds. The effect of the preparation conditions on the nanostructural characteristics and on the ionic conductivity, themomechanical and optical properties of these materials will be studied. The aim this research is to develop new transparent, or photolurninescent, solid ionic conductor hybrids based on siloxane-PEG or siloxane-PPG of several molecular weights and electrolyte loading, or doped with rare earth metals, respectively. Aiming to establish correlation among the preparation conditions, the structure and the properties, the effect of these parameters on the thermomechanical, nanostructural, of ionic conductivity and of luminescence properties will be studied.The study of thin layers based on the ceramic oxides (SnO2, ZnO e ZrO2) will be continued, aiming to establish new synthesis routes that allows the preparation of dense and hermetic films. We have shown that films prepared by dip-coating significantly improve the resistance to hydrolytic leaching of oxide and fluoride glasses. However, the performance of these materials, like as the electrical conductivity properties of the transparent electrode based on SnO2 and ZnO, can be improved by decreasing the permeability (porosity). In this step, the possibi1ity of increasing the sol-gel dip-coated films density by controlling the synthesis conditions of the sol-gel process will be focused. Moreover, nickel oxide electrochromic films will be prepared by the sol-gel process. At the end of this study we intend to be able to build up an all sol-gel rocking-chair electrochromic device employing the obtained solid electrodes, electrolytes and electrochromic films. Moreover, we intend also to develop photo and electro luminescent planar devices and wave guides. In the case of high surface area porous materials, we propose to continue the study of SnO2 based ceramic membranes and, we intend to start a project related to separation by filtration and preparation of thermal isolating films, comprising the study of preparation conditions of ZrO2 based ceramic foams by using the sol-gel process. (AU)