A Thermodynamic Perspective on Polymer Glass Formation

The dynamics of polymeric and other glass-forming liquids dramatically slows down upon cooling toward the glass transition temperature without any obvious significant change in their static structure. A quantitative understanding of this extraordinary dynamic slowdown remains one of the most significant challenges in condensed matter physics. Historically, extensive efforts have been devoted to explaining the dynamics of glass-forming liquids in terms of thermodynamic properties, leading to a number of semi-empirical models emphasizing distinct thermodynamic properties. Here, a thermodynamic perspective is provided on the glass formation of polymeric and other materials. We begin with an overview of the thermodynamic models of glass formation, including the intuitively appealing "free volume" models, enthalpy models originally emphasized by Goldstein and later by others, and the highly influential configurational entropy-based models. The review of these models is followed by a discussion of the advances that attempt to bring together some of the seemingly disparate thermodynamic viewpoints on glass formation by revealing a close interrelation between thermodynamic properties. We conclude this review with remarks on several key topics in this field, along with our viewpoint for future work.