In this project supported by the Chemical Structure, Dynamics and Mechanisms Program of the Division of Chemistry, Professor John Berberian and his students at St. Joseph's University will explore the molecular dynamics of glass forming systems, from their melting points to below their glass transition temperatures, Tg. The exemplary systems chosen for this study are the relatively simple symmetrical alkyl halides (specifically, 3 bromo 3 methylpentane, 3 bromo 3 ethylpentane, 1 bromo 2 ethylbutane and 1 bromo 3 ethylpentane) since they are devoid of hydrogen bonds and long range steric entanglements. This molecular system provides a systematic change in the length of the carbon chain at specific sites in the chain. Both modulated differential scanning calorimetry and dielectric relaxation are used to assess the changes in the configurational entropy with temperature (all of the molecular systems are dielectrically active) to test effect of molecular interactions in the Adam-Gibbs theory (cooperative rearranging regions). Additionally, the kinetics of the cold crystallization above Tg for these systems are investigated using isothermal modulated calorimetry and the measurement of the static permittivity both as a function of time and as a function of temperature.
The results of this study, along with previous results of similar systems, will provide deeper insights into the intermolecular interactions that give rise to the glass forming properties, and phase transitions in general. In turn, the understanding of the structure of materials on a molecular level will allow the team to predict the mechanical, thermal, and other properties of materials, such as polymers and polymer blend. The importance of such structural knowledge extends to a number of areas (drug industry, construction industry, health industry, etc.) which have the potential to increase the quality of life. As a Research at Undergraduate Institutions (RUI) project, the undergraduate researchers engaged in this project will receive a solid foundational experience in physical chemistry, as well as an opportunity to see direct implications in the materials sciences and beyond.
