Experimental Polymer Physics

 

Prof. Peggy Cebe


The polymer physics group conducts research on optical and electrical properties of macromolecules in relation to structure. Macromolecules exhibit a wide variety of organizational structures, including disordered liquid phases, thermotropic liquid crystals, and true three-dimensional crystals. The liquid-to-solid state phase transformations in liquid crystalline polymers and polymer melts is investigated using wide and small angle X-ray scattering. Our research group travels to the Brookhaven National Laboratory several times a year to conduct scattering experiments using the high intensity National Synchrotron Light Source.

In-house research facilities in the polymer physics group at Tufts include systems for measuring two-dimensional optical birefringence, electric dipole relaxation and thermally stimulated depolarization currents, heat capacity and thermal properties. Wide angle X-ray diffraction and molecular modeling capabilties also exist in the polymer physics group. One fundamental problem we are studying is the kinetics of phase transformation in polymers, and the competition between ordering (eg., isotropic-to-nematic-to-crystal) and phase separation under the influence of external fields. In another project in the nano-technology area, we are investigating the effects of restricted dimensionality on the phase transformation kinetics in crystallizable thin films. The research in this group is interdisciplinary in nature, combining solid state physics with materials science. Recent students graduating with the Ph. D. from this research group have been employed at Exxon Research Center, Michelin Americas Research Center, Tibco, and Cisco Systems.

 Selected Publications:

Patrick S. Dai, Peggy Cebe, Malcolm Capel, Rufina Alamo and Leo Mandelkern. “In-Situ Wide and Small Angle X-ray Scattering Study of Melting Kinetics of Isotactic Poly(propylene).” Macromolecules, 36(11), 4042-4050 (2003).

Baskaran Natesan, Hui Xu, B. Seyhan Ince, and Peggy Cebe. “Molecular Relaxation of Isotactic Polystyrene: Real-Time Dielectric Spectroscopy and X-ray Scattering Studies.” J. Poly. Sci., Poly. Phys. Ed., 42(5), 777-789 (2004).

Hui Xu and Peggy Cebe. “Heat Capacity Study of Isotactic Polystyrene: Dual Reversible Melting and Enthalpic Relaxation of Rigid Amorphous Phase.” Macromolecules, 37(8), 2797-2806 (2004).

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