Nano layer encapsulation using circulating supercritical fluid fluidized bed

A new and novel green process that allows nano layer by nano layer deposition in a fluidized bed through the use of circulating supercritical carbon dioxide doped with encapsulating material is developed. A minor temperature perturbation that tunes the solubility power of the coating material in the fluidizing carbon dioxide allows nucleation and encapsulation without conventional solvent-based atomization approaches. Therefore, a cleaner alternative to the use of organic solvents in micro encapsulating is achieved. The approach is particularly attractive for instances that necessitate moisture-free environment. The use of supercritical fluids intensify the fluidization and deposition rate reducing the processing time while increasing controllability. The technology developed by the group is applied for the microencapsulation of energetic particles such as ammonium nitrate, photo-catalyst such as titanium dioxide, and for targeted delivery of medically active compounds. The layer thicknesses achieved range from 5 to 50 nm while surface roughness of the products are within few nanometers. The presented applications illustrate unique properties achieved through the approach.