In the past few decades, ionic liquids (IL) have aroused tremendous strides in research and applications. This significant interest arises from their tunable physicochemical properties through proper selection of anion–cation combinations. However, despite all the benefits, it has been reported that many of ILs are toxic, non-biodegradable, high viscose, and expensive for mass production. A new alternative to overcome the drawbacks of currently employed ILs is to base their synthesis on renewable compounds such as amino acids from proteins. Amino acid-based ILs (AA-ILs) are an interesting and novel functional material, as amino acids have amino- and carboxyl- groups, a chiral center and a variety of side chains. While more research is necessary to find alternatives to currently used ILs, it is not practical to experimentally design and synthesize new IL candidates and determine their properties due to the wide variety of cation/anion combinations. As a promising tool, we use molecular dynamics (MD) simulations to design new bio-based ILs, and predict their properties. This knowledge will enable us to formulate the principles for designing new anion/cation combinations with desired functionality. In addition, selecting or developing a suitable force field (FF) is crucial in MD simulations in order to provide an accurate description of the behavior of ionic systems, in particular for anions due to their higher polarizability and much stronger environmental dependence compared to cations. Therefore, we used polarizable AMOEBA FF parameters to accurately represent bio-based ILs ([EMIM+][AA-], EMIM+=1-ethyl-3-methylimmidazolium) modeled in the current study, predict their structure and properties, and probe their application in various fields such as petroleum science, bioscience, and engineering. We determined their physicochemical and transport properties such as liquid density (), heat of vaporization (ΔHvap), heat capacity (Cp), diffusion coefficient (D±), and viscosity (μ), etc. Based on their structure, thermal stability and other characteristics, we explored whether they could replace conventional ILs without compromising the efficiency. We followed the AMOEBA procedure for parametrization of EMIM+ and AA-. These FFs will be available to the community and transferable to other studies.

Computational modeling of bio-based ionic liquids

ACS Spring 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.