Potential Applications of Nanostructured Metal Colloids

The obtained patterned polymer surfaces can also be replicated by metal thermal evaporation to produce nanostructured metallic films with holes or asperities of controlled size, as illustrated in Fig. 11.10. After deposition of a sufficiently thick metal layer, the polymer layer can be cleaved or dissolved away. This procedure allows an efficient and precise control of the metallic surface structure, with possible applications in materials science and photonics. The roughness of polydimethylsiloxane (PDMS) surfaces can be tuned by this technique if the PDMS is treated while cross-linking, which may be of interest for microfluidic applications. We have also observed that substrates of poly(methyl methacrylate) (PMMA), PS in the form of colloidal spheres and bulk, and semiciystalline films of polyethylene (PE) are prrMie to be structured by this technique, evidencing the versatility and potential for its widespread use. It may find applications in many different scientific and technological fields like nanoUthography, microfluidics, or flexible electronics. 

The nanoscale coating of colloid particles with materials of different compositions has been an active area of research in nanoscience and nanotechnology [2]. Deposition of metal nanoparticles on different colloid particles to form core-shell particles has been one of the most effective tools for achieving such composite nanostructures [172]. In particular, a number of studies on such composite structures were concentrated on the fabrication of metal coated latex particles, because of their potential applications in the fields of surface-enhanced I man scattering (SERS), catalysis, biochemistry, and so forth [173]. Conventionally, silver shells on polymer latex were prepared via wet-chemistry methods, which involve the activation of a latex surface by seeds of a different metal, followed by the deposition of the desired metal [174], or the modification of the latex with groups capable of interacting with the metal precursor ions on the latex surface via complex or ion pairs, and subsequent reduction [175]. 

Another application concerns the fabrication of metallic and bimetallic nanostructures on surfaces by electron beam induced metallization of the RjN Br"-stabilized Pd and Pd/Pt colloids [48]. In a simple three-step process, namely dip-coating, electron beam writing of patterns (e.g. lines) and rinsing, lines having a thickness of only 30 nm were achieved. This technique is of potential interest in lithography and catalysis. Finally, tetraalkylammonium salt-stabilized transition... 

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