Date of Award
Doctor of Philosophy (PhD)
Glasses are ubiquitous in our world, serving a wide array of purposes. An understanding of how to manipulate glass properties is essential to fully leveraging the usefulness of these materials. This requires an understanding of the relationship between chemical structure and properties, as well as investigation of the role of various methods of glass preparation beyond simple liquid quenching. A method that has gained recent attention is that of Physical Vapor Deposition (PVD) which, under the proper set of conditions, can result in glass states which behave as though highly aged. In this dissertation I explore the behavior of both liquid quenched and PVD glasses prepared under a range of deposition temperatures. Chapter 1 introduces the glass transition phenomenon and explores some properties of glasses, including PVD glasses. Chapter 2 uses differential scanning calorimetry and spectroscopic ellipsometry to probe the effect of chemical structure on bulk glass properties, including glass transition temperature and fragility. Chapter 3 uses in-situ ellipsometry measurements during vapor deposition process to explore how density and other properties change over the course of a stable glass deposition, including the possibility of phase transitions. Chapter 4 develops a method for nanoindentation of stable glass films, accounting for surface detection error. Chapter 5 describes mechanical properties of two chemically similar organic glass formers using this method, and compares hardness and modulus with other properties which vary with deposition temperature. This study provides a window to the role of molecular conformation on stable glass formation. Chapter 6 further considers soft surfaces of stable PVD glasses, using nanoindentation and atomic force microscopy to investigate how surface properties vary with glass-former and deposition temperature.
Wolf, Sarah, "Relationship Between Structure And Properties In Liquid-Quenched And Vapor-Deposited Organic Glasses" (2021). Publicly Accessible Penn Dissertations. 4917.