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Polyelectrolyte multilayers and nano-organized multimaterials

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Team leader: Prof. Gero Decher

Main activities :

Development of the layer-by-layer assembly method, macromolecules at interfaces, com-posite biomaterials, (bio)-functional nanoparticles, functional coatings, thin film devices, nanobio¬technology, hybrid materials.

Our most important activity is our invention and development of the so-called layer-by-layer (LBL) assembly method. This self-assembly method is a true bottom-up approach that is based on a straightforward concept (attractive intermolecular interaction, mostly electrostatic in nature) and combines experimental ease with low cost fabrication and environmental friendliness.

Who we are – have a look :

LbL-assembly allows to deposit a maximum number of different components on a maximum number of different surfaces in the form of multimaterial multilayer films using a single process. It has, over the last years, become a powerful tool for building polyelectrolyte multilayer films and more complex multicomponent systems with nanoscale precision. Over 200 independent teams are publishing now about 1000 articles per year in this field and LbL-films are used to coat objects as small as nanoparticles, as big as cars or as irregular as textiles or fruit. A huge advantage of LbL-assembly is that even films on very different surfaces can be astonishingly similar if prepared at identical deposition conditions. This allows for example to deposit films on surfaces that are difficult to characterize (e.g. paper, textile, fruit, ...) and to learn about their structure by doing x-ray or neutron reflectometry on regular silicon wafers.

The following 6 images show schematics of LbL-deposition (upper left) the dipping process (lower left), a freely-suspended film composed of 160 individual layers with a total thickness of 200 nm (upper middle), a functionalized nanoparticle (upper right), coated nanoparticles (lower middle) and one example of a recent commercial product that is made using our technology (eye contact lenses, lower right).

Today LbL assembly is used for applications as different as hydrophilic coatings on eye contact lenses (see above), separa¬tion layers in chromatography columns, the fabrication of optical filters, the application of super-hydrophobic coatings on cars, the direct coating of fruits and vegetables for enhancing their storage time, microencapsulation, anti¬coagulation coatings and third generation coatings on implants, nanoparticles for drug delivery, corrosion protection and several others.

Despite the enormous research activities in this rapidly developing field, we still discover fundamentally new systems such as purely inorganic films (e.g. CaF2, CaHPO4, …) and multilayers with surprising properties such as films with strong memory for solvents or self-patterning films. Current projects include work on separation membranes, catalysis, cytotoxic stealth nanoparticles or gene transfection