Stable polymer glasses

Abstract

This thesis presents investigations on stable polymer glasses prepared through physical vapour deposition from different perspectives. This is the first time that polymers have been used in simple vapour deposition and made into stable glass. The ability of our lab to create stable polymer glasses with exceptional stability and extremely long lifetimes is demonstrated through the preparation and characterization of ultrastable PS as well as PMMA glasses. Attempts at preparing stable polymer glass with higher molecular weight are reported, including two different methods–using higher molecular weight sources and crosslinking as-deposited glasses with ultraviolet radiation. The surface properties of stable polymer glasses including their surface morphology and surface relaxation are studied. With a slower bulk dynamics in stable glasses as expected, the surface evolution of the as-deposited films and the rejuvenated films are both enhanced compared to the bulk and are not easily distinguishable from each other. Investigations on stable polymer glasses confined to thin films are reported. The results support the existence of a surface mobile layer, and it is found that glass stability decreases with decreasing film thickness, as determined by different measures of stability. By studying stable polymer glasses from different perspectives in this thesis, we hope to provide valuable insights into many fundamental questions about the surface dynamics in thin films, the limit of packing in amorphous materials, and the nature of the complex and fascinating phenomenon–the glass transition.