Layer-by-Layer Electrostatic Self-Assembly
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Layer-by-layer (LbL) self-assembly of multilayer films involves the construction of complex composite materials with nanoscale precision in film thickness, one layer at a time, enabling the development of novel structures and devices with properties tailored by controlling the molecular makeup and arrangement. Early fundamental studies of multilayer assemblies on planar substrates demonstrated the practicality and versatility of the approach, and work over the past decade has included further investigation into the internal structure and composition of LbL films, including dynamic and long-term interactions between film components, solvents, and solute, especially transport properties. Beyond assembly onto flat planar surfaces, the multilayer deposition via LbL has been extended to colloidal templates, leading to elaborate modification of micro/nanoparticles and even to hollow capsules, both of which are exciting and attractive for many applications. While the bulk of work in LbL has been in experimental investigations, some efforts to generate theoretical descriptions for the multilayer assembly have also been undertaken, although much more work is needed in this area to establish useful models for design of devices based on this approach. Finally, applications for LbL films abound and are now being pursued at the academic level, with some examples of industrial success. Examples given here particularly focus on the biomedical arena, where sensor technology and drug release are prime candidates to benefit from use of multilayer films.