We have successfully coated CNTs with either positively or negatively charged polyelectrolytes employing Van der Waals interactions between nanotubes and polyelectrolyte molecules, without any previous chemical modification of the nanotubes walls. Polymer adsorption of polyelectrolytes was performed in an ethanolic solution, followed by redispersion in water. The surface coating was verified with ζ‐potential measurements and SEM. A sequential assembly of polyelectrolyte layers on top of the polyelectrolyte modified nanotubes has been achieved from a water solution following the layer‐by‐layer technique. The assembly of polyelectrolytes from water on CNTs deposited on a surface has also been shown with QCM‐D. Then, polyelectrolyte coated CNTs have been used as positive and negative blocks in the templating of layer‐by‐layer films.magnified image

The Langmuir and Langmuir-Blodgett (LB) techniques have been applied in a novel approach to build structurally well-ordered, oriented, and organized assemblies of water-soluble single-wall carbon nanotubes (ws-SWCNTs) at the air/water and air/solid interfaces. The SWCNTs were rendered hydrophilic by complexing them with a quenched polyelectrolyte. We observed that the ws-SWCNT concentration at the air/water interface increases with time condensing into different patterns, among which are isolated soap-froths, rings, and the aggregation of cumuli-like 2D-structures. These patterns were recorded at different compression-expansion stages by Brewster angle microscopy (BAM). From the isotherm measurements, we are able to determine the diffusion process by which ws-SWCNT concentration builds up at the water surface. The corresponding LB films were very stable and could be transferred onto mica substrates easily. Atomic force microscopy (AFM) images revealed that the morphology of these films is surface-pressure dependent, and aligned structures with a nematic-like order formed closely packed mono- or multilayer films. The assembly of 2D-nanostructures by means of this approach offers a great potential for emergent technological applications using modified water-soluble SWCNTs.

Summary: Assemblies of oppositely charged L‐lysine/carboxylic acid functionalized polyphenylene dendrimers and hybrid multilayers of L‐lysine dendrimers/colloidal gold nanocrystals were fabricated as alternate multilayers on 3‐mercaptopropionic acid coated gold surfaces via layer‐by‐layer deposition. The fabrication of the multilayer films was monitored by kinetic and scan mode surface plasmon resonance spectroscopy. The permeability properties of the dendritic polyelectrolyte layers were characterized by electrochemistry in the presence of [Fe(CN)6]3−/4− as the redox couple. A high interfacial charge‐transfer resistance, originating from the electrostatic repulsion of the negatively charged redox couple against the negatively charged interface was observed and the charge‐transfer resistance found to increase with increasing number of layers.3D‐structure of the investigated polyphenylene dendrimers: a) G2(L‐lysine)8 and b) G2(COOH)16.magnified image3D‐structure of the investigated polyphenylene dendrimers: a) G2(L‐lysine)8 and b) G2(COOH)16.

No abstract

No abstract

No abstract

This paper describes some of our efforts in the area of nanostructured thin film architectures. The resulting interfacial hybrid assemblies are built from (1) organic/polymeric objects based on dendrimer systems, from (2) surface-functionalized Au nanoparticles, and (3) from a variety of semiconducting quantum dots. Dendrimers as polymeric building blocks with a strictly monodisperse particle size distribution in the nanometer range can be functionalized in the core, the scaffold, or at the periphery, thus offering interesting hybrid materials for a wide range of applications. The combination with Au clusters and their local surface plasmon resonances suggests new strategies for optoelectronic devices or unconventional bio-sensor platforms. The possibility of tuning the luminescent properties of semiconducting nanoparticles by size or compositional bandgap engineering complements the assembly kit with building blocks for supramolecular thin film nanocomposite materials.

No abstract