Coating of ultra-fine particles using supercritical Fluids

Document Type

Conference Proceeding

Publication Date

12-1-2006

Abstract

Nanosized particles have a wide range of industrial applications. In certain applications, particle surfaces need to be modified or functionalized by coating them with another material to serve a specific purpose. As nanoparticles are extremely cohesive, it is very difficult to coat an individual particle by traditional methods. In this paper, nanoparticles coating is investigated through Supercritical Fluid-based methods. Agglomeration of coated particles is reduced by combining two approaches. The first approach uses a proprietary co-axial ultrasonic nozzle to spray the solution suspension into the SC CO2. Ultrasound is very effective in breaking agglomerates and the introduction of the co-axial flow enables CO2 to not only serve as an antisolvent, but also as mixing enhancer. The second approach uses a combination of thermodynamically good and poor solvents to tune the supersaturation of the polymer, which serves as the coating material. PMMA film is coated on different kinds of nano-silica particles. In addition, effects of flow patterns through ultrasonic nozzle on particle coating and agglomerations are studied. Silica particles are also pre-treated to alter the dispersion into media. With pre-treating silica surfaces the zeta potential of the suspended silica particles can be altered and hence dispersion could be controlled. Various imaging techniques such as FE-SEM (field emission scanning electron microscope), TEM-EELS (transmission electron microscope-electron energy loss spectroscopy), and EDS (energy dispersive x-ray spectroscopy) are used to characterize the coating of particles. Photon correlation spectroscopy is used to measure the size distribution of particles before and after coating. TGA (thermal gravitational analysis) and DSC (differential scanning calorimetry) techniques are used to study the amount and thickness of coating.

Identifier

80053693368 (Scopus)

Publication Title

Aiche Annual Meeting Conference Proceedings

This document is currently not available here.

Share

COinS