Layer by layer assembly (LBL) is a method of thin film deposition which is often used for oppositely charged polymers. Recently this approach has been applied to the preparation of thin films composed of nanoparticles, owing to its simplicity and versatility, complemented by high quality of resultant films. LBL films are typically made by routinely dipping the substrate into polyelectrolyte solutions of alternating charges. The entire cycle is repeated several hundred times. While semi-automated systems exist, the present techniques do not reliably reproduce films with equally distributed solutions, and may only produce films of limited size.
Researchers at the University of Michigan have developed a device for the automated LBL assembly process. The device and process includes the application of one or more polyelectrolyte solutions to a continuously moving substrate. The device consists of a roller, a cylindrical substrate, and a motor which rotates the substrate to provide polyelectrolyte solution to the surface of the substrate. Excess solution may be rinsed off using the optional rinsing nozzle and air applicator. Multiple bilayers are produced by continuous application of the polyelectrolyte solutions to form LBL films or nanocomposite materials, which is then removed from the substrate.
Applications and Advantages
- nanomaterial and film production by layer by layer assembly
- automated system, with increased reproducibility and speed
- ability to make larger films