Uncovering the Solvent–Solute Interaction Mechanism in Nucleation of Erythritol Based on Metastable Zone Widths: Experimental Kinetics and Molecular Dynamics Simulations

The polythermal method (PTM) was employed to measure metastable zone width (MSZW) of erythritol (ERT) in solvents containing different hydrogen bond acceptor (HBA) capacities. The nucleation behavior of ERT was explained by modified Sangwal’s theory. In order to further uncover the effect of interaction mechanism between solvent and solute molecules on the nucleation rate of ERT, the molecular electrostatic potential surface (MEPS), Hirshfeld surface (HS) analysis, and radial distribution function (RDF) were calculated and analyzed. It was found that the strength of solvent–solute interaction was mainly related to the HBA ability of the solvent: the greater the HBA ability was, the stronger the hydrogen bond between the solvent and solute molecules would be, resulting in more difficulty for the solute to separate from the solvent, which then widens the MSZW and leads to a lower nucleation rate, a smaller critical nucleation size, and a longer induction time. Additionally, the induction time under different supersaturation ratios was measured to analyze the nucleation mechanism of ERT. At a high supersaturation ratio, the nucleation mechanism was homogeneous, while at a low supersaturation ratio, the nucleation mechanism was heterogeneous. The calculated interface energy based on the classical nucleation theory was compared with the interface energy calculated by modified Sangwal’s theory. The two calculated values were in good agreement, which further lay the foundation for the application of modified Sangwal’s theory.