Molecular structural analysis of hydrated ethylene glycol accounting for the antifreeze effect by using infrared attenuated total reflection spectroscopy

Abstract

To reveal the antifreeze protection mechanism of an aqueous solution of ethylene glycol (EG) at a molecular level, concentration-dependent infrared spectra are analyzed with an aid of chemometrics. The principal component analysis (PCA) of the spectra reveals that the spectral variation is explained by the quantity changes not only of 'bulky water' and the 'bulky EG,' but also of a 'water/EG complex.' After a spectral decomposition using the alternative least squares (ALS) analysis, the spectrum of the complex reveals that the EG molecule keeps the gauche conformation, and the terminal hydroxyl groups are hydrogen bonded by water molecules, which is a key to understand the antifreeze effect. In addition, the complex is found to comprises an EG molecule with four water molecules. Since the quantity of the complex attains the maximum at an EG concentration of 60 wt%, at which the freezing point becomes lowest, the complex is concluded to be a key hydrated species for the antifreeze effect. The generation process of the water/EG complex is also studied by using the time-resolved IR spectroscopy, which consistently confirms the spectral discussion made above.

Electricity Generation and Self-Powered Sensing Enabled by Dynamic Electric Double Layer at Hydrogel–Dielectric Elastomer Interfaces

“…Despite the reduced contact electrification at the hydrogel–PTFE interface, the two following beneficial effects are obtained using the water–EG mixture in the hydrogel. First, the EG is commercially used as an antifreeze agent, which can reduce the freezing point of the mixture, thereby widening the operation temperature range of the device . Typically, the mixture has the best antifreeze properties with an EG volume percentage around ∼40–60% .…”

“…First, the EG is commercially used as an antifreeze agent, which can reduce the freezing point of the mixture, thereby widening the operation temperature range of the device. 42 Typically, the mixture has the best antifreeze properties with an EG volume percentage around ∼40−60%. Therefore, the water-to-EG ratio was selected as 3:2 for the hydrogel.…”

Aqueous Lithium-Ion Battery of Nano-LiFePO4 with Antifreezing Agent of Ethyleneglycol for Low-Temperature Operation

“…Where, the adding of suitable antifreeze additives into aqueous solutions can reduce the freezing point and other parameters such as the low viscosity and wide liquid range, which impact on the improvement of the low-temperature performance of aqueous battery systems. Furthermore, it can be suggested that adding EtG into aqueous electrolyte solutions on the surface of the LiFePO 4 materials can form a complex of aqueous electrolyte solution and EtG . In the case of using the EtG as an antifreeze agent that is an organic additive, the low-temperature performance of the LiFePO 4 materials is superior to those without the EtG.…”

Survey to Identify Substandard and Falsified Tablets in Several Asian Countries with Pharmacopeial Quality Control Tests and Principal Component Analysis of Handheld Raman Spectroscopy

“…Our previous study found that the types of the excipients used in candesartan cilexetil tablets differ depending on the manufacturer, and Raman spectra of the tablets showed the different pattern reflecting the chemical nature of the excipients. 34 Here, we focused on the methodology for detecting substandard and falsified medicines by principal component analysis (PCA) 12,22,[35][36][37][38][39][40][41][42][43] of raw data obtained by handheld Raman spectroscopy. We aimed to clarify the chemical features of substandard medicines by comparing them with authentic medicines, and by extracting the principal components of the Raman spectrum to visualize the relationships among the tablets.…”