Experimental Physical Chemistry Applications for Material Science: The Neutron Vibrational Spectrum of Biaxially-Oriented PET and HKUST-1 as a QCM-Based Ethylene Sensor

This work is divided into two comprehensive subjects exploiting fundamental properties of physical chemistry to understand applied materials. The two subjects will be: the inelastic neutron scattering of thin polyethylene terephthalate (PET) films and the design and development of a quartz crystal microbalance-based ethylene detector. For the work involving the thin films, the inelastic neutron scattering (INS) was accomplished using the high flux of the VISION vibrational spectrometer at the Spallation Neutron Source yielding the highest quality data currently available. The torsional vibrational modes of biaxially-oriented PET (bPET) will be reported with the help of DFT calculations to aid in assignment of normal modes in the INS spectrum. This work will provide a template for more complex polymer systems as well as give insight into the dynamical change taking place upon biaxial orientation. This fundamental study was a necessary step in understanding the macroscopic properties of decorated thin films through the Eastman Innovations Network. However, due to the proprietary nature of the composition of the decorated thin films, this section will focus solely on the fundamental results.

The second subject of the study moves past mere fundamental studies to a more materials application topic via the decoration of a quartz crystal microbalance (QCM) to facilitate the selective binding of ethylene gas for applications in gas sensing. The molecule used in the decoration was HKUST-1, a metal organic framework (MOF), with a high surface area and increased affinity for ethylene gas. The high sensitivity of the QCM produces the ability to directly measure gas adsorption in the nanogram regime while maintaining a +/- 0.1 Hz stability. This study will present a comparison of interactions with different gases, a brief thermodynamic study of the ethylene-HKUST-1 interaction to acquire the heat of adsorption, and early in operando measurements using the ethylene produced from the ripening of bananas.