Carboxyl Versus Amide Groups Influence Towards Physicochemical and Thermal Properties of Choline Based Deep Eutectic Solvents
Theaveraj RAVI, Asiah Nusaibah Binte MASRI, Erny Izzaty MOHD NOR, Nur Ain Nabila HARMEN, Hasrinah HASBULLAH, Wan Zaireen NISA YAHYA, Izni Mariah IBRAHIM, Rahmat MOHSIN, Mohammad Afiq ZUBIR, Intan Suhada AZMI, Jean-Marc LEVEQUE
Abstract. This paper provides a thorough comparative analysis of the physicochemical and thermal properties of new deep eutectic solvent (DES); choline chloride – glutaric acid and the common DES; choline chloride – urea. The significance of choline chloride based deep eutectic solvents (DES) lies in their environmentally benign characteristics and their potential utilization in diverse industries owing to their low toxicity and ability to degrade naturally. Integrating ChCl with hydrogen bond donors having carboxyl group (GA) or amide group (urea) would open green application opportunities in bioprocessing, polymerization and extraction processes. In this study, the characterization encompasses of structural characterization through Fourier-transform infrared spectroscopy (FTIR), physicochemical characterization involving measurements of viscosity and refractive index and thermal characterization using techniques such as thermogravimetric (TGA) analysis and differential scanning calorimetry (DSC). Based on the viscosity and refractive index measurements, it can be observed that ChCl – GA has a higher value, followed by ChCl – urea. When it comes to melting temperatures, ChCl – GA has the lower melting point, which is 91.47 °C, whereas ChCl – urea has a slightly higher melting point of 98.02 °C. Thermal analysis was performed on both types of DES using TGA, with heating rates of 5, 10 and 15 °C/min, and a temperature range of 50 °C to 700 °C. The thermogravimetric study results showed that the ChCl – urea had greater thermal stability than ChCl – GA. By conducting a comprehensive examination of kinetic parameters, including activation energy (Ea) and pre-exponential factor (log A), using the Kissinger-Akahira-Sunose (KAS), Flynn-Wall-Ozawa (FWO) and Starink methods, it was concluded that the ChCl – urea compound exhibited lower average Ea and log A values compared to ChCl – GA. This difference can be attributed to the higher thermal stability of ChCl – urea. Our work established a robust correlation between the onset temperature (To), decomposition temperature (Tmax), log A, Ea, and the values of DESs, indicating their thermal stability. In conclusion, ChCl – urea shows lower viscosity, lower density value, higher melting point and high thermal stability. Thus, it is suitable for any application that requires efficient flow properties and stability under high temperatures. ChCl – GA shows higher viscosity, higher density, higher melting point and low thermal stability. Thus, it would be suitable for applications requiring more robust, denser solvents that operate at lower temperatures.
Keywords
Thermogravimetric Analysis, Deep Eutectic Solvents, Onset Temperature (To), Decomposition Temperature (Tmax), Physicochemical Properties, Carboxyl, Amide
Published online 5/10/2026, 18 pages
Copyright © 2026 by the author(s)
Published under license by Materials Research Forum LLC., Millersville PA, USA
Citation: Theaveraj RAVI, Asiah Nusaibah Binte MASRI, Erny Izzaty MOHD NOR, Nur Ain Nabila HARMEN, Hasrinah HASBULLAH, Wan Zaireen NISA YAHYA, Izni Mariah IBRAHIM, Rahmat MOHSIN, Mohammad Afiq ZUBIR, Intan Suhada AZMI, Jean-Marc LEVEQUE, Carboxyl Versus Amide Groups Influence Towards Physicochemical and Thermal Properties of Choline Based Deep Eutectic Solvents, Materials Research Proceedings, Vol. 66, pp 80-97, 2026
DOI: https://doi.org/10.21741/9781644904152-9
The article was published as article 9 of the book Advanced Materials and Sustainable Energy Technologies
Content from this work may be used under the terms of the Creative Commons Attribution 3.0 license. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.
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