Valerie Moses, Ph.D. (2003) 

Dissertation Topic:  Effects of Substituent Geometry on the Structure-Property Relationships of Substituted Syndiotactic Polystyrene

Major Professor:  Dr. Adriane Ludwick, Professor of Chemistry &  Dr. Derrick Dean, 3M Massey Chair and Associate Professor of Mechanical Engineering

M.S.: Chemical Engineering, North Carolina A&T University

B.S.: Electrical Engineering, Morgan State University

Employment: United Technologies, Connecticut 

Dissertation Abstract:

We are interested in elucidating the structure-property relationships in a family of syndiotactic polystryrenes with highly controlled molecular architecture. In some instances, the phenyl ring will be modified with various substituents. These variations will yield polymers that are amorphous as well as semicrystalline. We will utilize a range of thermal, thermo mechanical, microscopic and x-ray diffraction techniques to determine the morphology of these polymers as a function of regioplacement and composition as well as after subjection to a range of processing histories. Degrees of crystallinity, crystallite and lamellae size will be studied. The regioplacement and composition is expected to significantly affect the relaxation behavior. Dynamic mechanical analysis will be used to study this behavior. The activation energies associated with the main chain relaxations (T g) and sidechain relaxations will be determined and correlated with predictions from molecular modeling calculations. Mechanical properties will be studied as a function of the parameters discussed above. This information will also be correlated with molecular modeling calculations.