Changes Of Physical Properties Of 1,3-Dimethylimidazolium Methanesulfonate And Their Prediction By Machine Learning

Ionic liquids are a unique type of liquid consisting entirely of cations and anions,and have an internal structure different from that of traditional molecular media.The microscopic structure determines the properties,and a detailed study of the interactions and motion of ions in ionic liquids can help better understand their structure and properties.Due to the complexity of their physical properties involving factors such as ion-ion interactions,solubility,ion transport,and thermodynamics,studying the properties of ionic liquids requires various experimental techniques and theoretical models to better understand their structure and properties.Starting from the study of the microstructure and kinetic properties of ionic liquids,this paper further expanded the study of the physical properties of different ionic liquids,and adopted the calculation method of combining Liquid Lib and Lammps to study the changes of the physical parameters of ionic liquids from the microstructure.The ionic liquid data calculated by Lammps were used to establish a machine learning prediction model.The feasibility of predicting physical properties of ionic liquids using a neural network model was verified.The above research provides an important theoretical basis and reference for exploring the microstructure and physical properties of ionic liquids,and has significant value for the practical applications of ionic liquids.First,an ionic liquid model was built using Molltemplate,and Lammps was used to simulate the system’s relaxed state at different temperatures.Liquid Lib was then used to analyze the microstructure and dynamic properties of 1,3-dimethylimidazolium methanesulfonate(DMIMSA)at different temperatures.It was found that the DMIMSA ionic liquid has a structure characterized by short-range order and long-range disorder.It was also found that at low temperatures,the movement of cations was higher than that of anions.Cations not only showed a decrease in movement ability but also appeared in the system’s non-uniform part at low temperatures,while anions only showed kinetic retardation.To deepen the understanding of the effect of substituent alkyl chain length of cations and anions on their physical properties in ionic liquids,25 different ionic liquids were formed by increasing the substituent alkyl chain length of cations and anions based on DMIMSA ionic liquid,and the physical properties of density,viscosity,thermal conductivity,and diffusion coefficient were calculated by Lammps simulation for these 25 ionic liquids.It was found that an increase in the substituent alkyl chain length of anions led to an increase in the system’s movement ability.The interaction of the nearest neighbor distance increased with an increase in the anion’s substituent chain length,while the interaction of the next nearest neighbor distance decreased with an increase in the anion’s substituent chain length.With an increase in the substituent alkyl chain length of cations and anions,the density of the ionic liquid gradually decreased.The maximum viscosity was observed when the substituent alkyl chain length of cations and anions was 1,and the minimum thermal conductivity and diffusion coefficient were observed when the substituent alkyl chain length of cations and anions was 5.