Insights into the Role of Solvents in Nucleation Kinetics of Glutaric Acid from Metastable Zone Widths

In this paper, the nucleation behavior of glutaric acid (GA) in solvents with different hydrogen-bond donating (HBD) capabilities was studied using a metastable zone width (MSZW) experiment and modified Sangwal’s theory. Through designing different cooling rates, saturation temperatures, and solvents with different HBD capabilities, it is demonstrated that the MSZWs increase when increasing the cooling rate or decreasing the saturation temperature or increasing the HBD capability. Interestingly, under the framework of the classical nucleation theory, we find that the critical nuclei size and critical Gibbs free energy do not monotonically change with the increase of driving force in the three solvents, which means that the solid–liquid interface energy changes with the driving force. Finally, we suggest that with increasing HBD capability, desolvation of glutaric acid becomes more and more difficult, thus leading to a wider metastable zone width, which indicates that desolvation may be the rate-determining step in the nucleation process.