Introduction to Particle Surface Modification: Coating, Encapsulation and Gradient Functionalization


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.

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Topics Covered:

Particle Surface Modification


        Solvent Evaporation Processes
            Wet impregnation, Incipient wetting, Spray drying
        Thermal Phase Separation
        Physical Vapor/Atomic Flux Deposition
        Polymer Adsorption/Steric Stabilization


        Chemical Vapor Deposition
        Spray Pyrolysis
        Aerosol Droplet Reactions
        Reactions on Powder Surfaces in Liquid Dispersions
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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.

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(C)  2002  Particles Conference