Glass Transition Kinetics and Physical Aging of Polyvinylpyrrolidones with Different Molecular Masses

The stability of glassy materials, including polymer-based ones, is one of the important subjects of material science and technology. This interest is due to the dependence of the properties of the end products, based on glassy materials, on the processing and storage conditions. In particular, the application of amorphous solid dispersions based on polymer excipients requires an understanding of the kinetics of the formation and the physical aging of the glassy state. The kinetic parameters of the glass transition of polyvinylpyrrolidone, a widely used polymer in the pharmaceutical industry, were determined in the present work using fast scanning calorimetry. The dependencies of the Vogel temperature and the kinetic fragility on the molecular mass of the polymer were determined, as well as the apparent activation energy of the physical aging process, which changes from 256 kJ·mol–1 in the case of polyvinylpyrrolidone with a molecular mass of 3500 g·mol–1 to 565 kJ·mol–1 in the case of polyvinylpyrrolidone with a molecular mass of 1,300,000 g·mol–1. The results of the current work can be used to optimize the processing of polymer-based glassy materials to obtain the desired properties for application in different fields of technology, including pharmaceuticals.