Layer-by-Layer assembled nanocomposites

28 May 2007

The layer-by-layer assembly (LBL) is a comparatively new method by which thin films particularly of oppositely charged layers are deposited. Thin film layer-by-layer assembly technique can also be utilized for nanoparticles. In general the layer-by-layer assembly is described as sequential adsorption of positive or negative charged species by alternatively dipping into the solutions. The excess or remaining solution after each adsorption step is rinsed with solvent and thus we get a thin layer of charged species on the surface ready for next adsorption step.

There are many advantages of layer-by-layer assembly technique and these include simplicity, universality and thickness control in nanoscale. Further the layer-by-layer assembly process does not require highly pure components and sophisticated hardware. For almost all-aqueous dispersion of even high molecular weight species, it is easy to find an LBL pair that can be useful for building thin layer. Actually in each adsorption step, we get either a monolayer or a sub monolayer of the species and therefore we can find the number of adsorption steps needed for a particular nanoscale layer.

The variety of species and components are available for layer-by-layer assembly process and this has led to an exceptional growth in the LBL nanocomposites. Further organic-inorganic composite can act as functional groups and that can improve the performance of the material. Many biomolecules show polyelectrolyte nature and further the characteristics distance will lead the new direction in biomedical applications of planar LBL film. Photonic materials are being examined especially luminescent nanoparticles in multiplayer films that can enable to get a new biocomposites.

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