Layer by Layer Assembly of Thin Films

Preparation of ultrathin polyelectrolyte multilayers by alternating adsorption of polyanions and polycations is relatively simple. A charged substrate of any size or shape can be immersed into a solution of polyelectrolyte with a net charge opposite to the surface charge. The polymer adsorbs on to the substrate within a couple of minutes because of the electrostatic interactions, resulting in the surface charge reversal. Rinsing removes the unbound polymer from the substrate, preparing it for the next deposition step of oppositely charged polyelectrolyte. This rather simple technique has several advantages. The film synthesis is straightforward, inexpensive, and reproducible. No harsh solvents are needed. There are no restrictions to the substrate size, shape or material. There is also a huge number of different materials that can be used in the multilayer formation. Incorporating different materials into the multilayer films is fairly simple. In principle, any macromolecule that is charged when dissolved in aqueous or organic solutions is potentially suitable.

One of the general aims of this research is to generate technology for producing nanomaterial in the highly repeatable manner. The LbL-films can be rather easily combined with conducting polymers, redox polymers and carbon based nanomaterials. In addition to that the nanometer-scale control over the deposition process gives tools for tailoring the overall functional structure of the composite films. The ultimate goal is to generate functional devices composed of structurally defined composite films – a new technology of spray deposited functional devices with extremely low production cost even for large area processing.

LbL fabrication target 480 x 384

Vapor phase polymerization (VPP)