Uncovering the Coupling Mechanism of Enhanced Growth of Acephate by Additives: Experiments and Molecular Dynamics Simulations

In this study, the effects of polyethylene glycol (PEG) and polyvinylpyrrolidone (PVP) on the nucleation and crystal growth kinetics of acephate were systematically investigated. The differential effects of PVP and PEG with varying molecular weights on the primary and secondary nucleation of acephate were uncovered. In addition, the effect of additives on the crystal growth rate was also measured, which uncovered that micromolar concentrations (4.25 x 10(-5) M) of PEG at low supersaturation can substantially promote crystal growth. Moreover, a cooling crystallization experiment was designed to further demonstrate the potential of PEG to promote crystal growth in practical applications. Finally, the coupling mechanism of additive-promoting crystal growth was elucidated based on the experimental and molecular simulation results. On the one hand, it comes from the facilitation of solute diffusion in solution, resulting from the additives' attraction to solvents. On the other hand, it is from the additives' disruptive effect on the solvation layer near the crystal surface. This might be used to guide additive selection.

Automated summary

The effects of polyethylene glycol (PEG) and polyvinylpyrrolidone (PVP) on the nucleation and crystal growth kinetics of acephate were systematically investigated in this study. It was found that PEG and PVP with different molecular weights had differential effects on the primary and secondary nucleation of acephate. Furthermore, micromolar concentrations of PEG were found to substantially promote crystal growth.