Recently, there is much interest in hybrid materials consisting of metal nanoparticles dispersed in a polymer matrix due to their novel functional properties offering hosts of new applications. The present talk is concerned with the preparation of polymer-based nanocomposite films by vapor phase co- and tandem-deposition and their resulting functional properties. The deposition techniques involve simultaneous evaporation of the organic and metallic components (noble and transition metals) and inter alia allow the preparation of composites containing alloy clusters of well defined composition. The polymer films are deposited either by evaporation of the monomers and subsequent polycondensation on the substrate or by thermal cracking of suitable polymers (e.g. Teflon AF®, Nylon, PAN, PaMS etc.) and repolymerization of the fragments on the substrate. The chemical structure of the polymer matrix was studied with FTIR and XPS, and was found to be close to the pristine polymer. The structural properties of the composite films was characterized by TEM. The metallic nanoclusters are spherical and are uniformly dispersed in the polymer matrix. Their size and distribution in the polymer matrix depend on the deposition parameters as well as on the metal-polymer interaction and the metal filling factor [1]. The condensation coefficient of the metal atoms as well as the rate of nucleation and growth of the nanoclusters depend strongly on the flux ratio of the organic and metallic components. For example, when co-evaporating an FeNiCo with Teflon AF® at elevated temperatures, it was found that beyond a critical flux ratio a self-organization process leads to the formation of metallic nanocolumns in the polymer matrix [2]. Another approach that will be discussed is the application of ion assisted tandem evaporation to prepare multilayers with exactly defined nanoparticle size and densities. Finally, we will report about the properties of such nanocomposite films for the application as magnetic and optical, and antimicrobial coatings.
[1] H.Takele et al. Nanotechnology 17, 3499 (2006)
[2] H.Greve et al. APL 88, 123103 (2006) |