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March 1, 2006


Dr. Michael MacKay
Professor of Chemical Engineering and Materials Science
Michigan State University
"Nanoscale Phenomena in Polymers Do they Measure Up?"

Abstract. In this seminar I discuss how nanoparticles affect the properties of linear polymers. It is found that nanoparticles are soluble in linear polymers, despite chemical dissimilarity, when the nanoparticle is smaller than the linear polymer. If the particle becomes larger than the polymer, phase separation occurs. In addition, small angle neutron scattering shows the linear polymer becomes distorted in the stable systems and far from its equilibrium conformation. This aspect demonstrates the uniqueness of nanoscale thermodynamics as phase separation is expected (i.e. depletion flocculation) and we argue that nanoparticles are stabilized upon dispersion by enthalpic gain. Furthermore, the melt viscosity of the system falls below that of the pure polymer, what we call non-Einstein behavior, demonstrating the effect the distorted polymer has on this transport property. The above and other unusual nanoscale phenomena will be discussed in the seminar.

Vanderbilt University