CREATION OF NANO-PATTERENED POLYELECTROLYTE MULTILAYERS

Nano scale, periodic patterned surfaces attract a considerable interest due to their wide applicability in a range of industrial and research fields, such as optics – where a well-defined periodicity is crucial to allow conductance of specific wavelengths of light, or in the field of catalysis – where the ability to create a periodic pattern with a high surface area to volume ratio is extremely important for chemical reactions to take place. A well-defined nano-scale pattern usually involves a distinguishable chemical/physical contrast on the surface. To this day, these patterns are achieved usually by E-beam lithography, which is a very expensive and time consuming process.

In this work we present a non-lithographic solution for the creation of such patterns, using a combination of two self-assembly approaches: micro-phase separation of block copolymers and layer-by-layer deposition of polyelectrolytes. Block copolymers are consisted of two chemically distinct polymers joined together by a covalent bond that self-assemble upon annealing into various ordered microstructures such as lamellae and cylinders, with periodicities of few nanometers. These block copolymer surfaces serves as templates for a selective layer by layer deposition of polyelectrolytes upon them. The Layer-by-Layer (LbL) technique, which is a building approach of polyelectrolyte multilayers that relies on the electrostatic interactions between negatively and positively charged polyelectrolytes, can be used to create multi-layer arrays of controllable composition, by alternately Deeping the templates in oppositely charged polyelectrolyte solutions. Applying the Layer-by-Layer technique over block copolymer surfaces for domain-specific electrostatic depositions can serve us for the creation of nano-structured three dimensional films exhibiting a well-defined height contrast, in addition to chemical contrast between two distinguishable domains, thus creating a 3D nano-scale pattern which consists of a polyelectrolyte multi-layer (PEM).

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