Improved controlled release of therapeutics, stronger ceramic and metal composites, and improved electronic and thermal properties of devices are examples of the importance of knowing how to control particle surfaces. The purpose of this Short Course is to introduce interested materials technologists to the several methodologies that have been developed to modify the surfaces of particulate matter, i.e., to create core-shell composite particles. To achieve that goal the subtopics are divided into two parts, Physical versus Chemical. The majority of the processes result in deposition of the coating material onto the exterior of a core. A few may also result in surface modification of internal pores by adsorption of material during deposition.
The division of the subtopics is based upon whether or not the material being deposited as the coating or shell undergoes chemical change, or is chemically created during the process. The physical methods involve only transport of preformed coating material from a source to the particle.
The chemistries to be covered differentiate surface treatment by tethering functionally gradient molecules, versus covering the core surface with bulk, multimolecular layers of (polymeric) inorganic or organic material. In either case, however, the procedures involve synthesis of the coating from dissolved monomeric precursors in a dispersion of the core particles.
The scientific fundamentals presented are complemented
by use of practical examples where industrial powders have been transformed
to be more valuable
in materials processing.
Solvent Evaporation Processes
Wet impregnation, Incipient wetting, Spray drying
Mechanofusion
Thermal Phase Separation
Physical Vapor/Atomic Flux Deposition
Polymer Adsorption/Steric Stabilization
CHEMICAL METHODS OF PARTICLE SURFACE MODIFICATION
Instructor
Professor Richard Partch holds the positions of Senior University
Scientist at the Engineering Research Center, University
of Florida and Senior University Professor at Clarkson University in the
Center for Advanced Materials Processing. He earned his PhD in synthetic
organic chemistry and has gained reputation in areas such as mechanisms
of oxidation of alcohols by metal ions, in the synthesis of several classes
of potential medicinal agents including steroid, porphyrin and neurotransmitter
derivatives, and more recently, in the field of synthesis and surface modification
of many compositions, shapes and sizes of particles. The surface modifications
include the formation of continuous and uniform coatings of bulk amount
of a chemical generated and deposited during in situ synthesis of the coating
material in a dispersion containing the core particles, and covalent tethering
of surface functionalities to obtain functionally gradient powders.
His publications contain both fundamental and applied information.
He has co-pioneered and demonstrated aerosol droplet reaction techniques
for preparation of single and multicomponent particles; developed and optimized
particle coating methods using gas phase, aerosol and solution techniques.
(C) 2002 Particles Conference