(7hv) In silico Design of Ionic Liquid Adducts for Biomedical and Electrochemical Applications

Ionic liquids (ILs) are materials with a low degree of toxicity that can be incorporated in a variety of drug formulations. Due to their non-flammability and high ionic conductivity, they can also be used in energy storage and electrochemical applications. My research will focus on the computational design of ILs for these applications including the creation of efficient numerical methods for computing the strong electrostatics interactions inherent to these systems.

Design ILs that increase the bioavailability of drugs: The biggest obstacles facing drug development today are limited bioavailability and water solubility, low dissolution rate, and polymorphic crystalline structure of a drug. Polymorphism of the drug leads to different physical properties, such as water solubility. The goal of this research is to increase the water solubility and stability of drugs, such as Brivudine and trifluridine, which are anti-HIV drugs with low bioavailability by means of ILs. A drug or active pharmaceutical ingredient (API) can be combined physically or chemically with an IL to produce a modified drug (prodrug) in a form of an active liquid salt that increases the solubility and limits undesirable polymorphic crystalline structures. Simulation tools, such as molecular dynamics (MD) and density functional theory (DFT) will be employed to characterize the interaction of different anions and cations with water molecules and to elucidate the microstructure and spatial characteristic of pure ILs and IL modified drugs (API-IL). An atomistic force field will be developed as a benchmark to determine the physicochemical properties of API-ILs systems. Further, a coarse-grained model of API-ILs will be proposed in order to remove the limitations of short time scales in atomistic simulations.

Design ILs that build a uniform solid-electrolyte interface (SEI) in batteries: Batteries operating at ambient operating temperatures have low ionic conductivity (10^-3 S cm^-1) and metal cycling efficiency, and have raised safety concerns due to the incompatibility of the metal with the electrolyte. ILs are of a great interest as electrolytes because of their high ionic conductivity, excellent thermal stability, and non-volatility. For example, ILs can increase the conductivity of poly (ethylene oxide) (PEO) electrolytes by a factor of 10 in batteries. Thus, the conductivity of the electrolyte can be tuned by changing the ratio of the PEO to IL. The SEI, which is the result of the reduction of the electrolyte solvent and the lithium salt at the anode surface, controls the lifetime of a battery. To optimize battery performance a clear understanding of the composition and structure of the SEI is needed for alkali metal batteries. Simulation techniques, such as quantum chemistry and atomistic MD simulations using a reactive force field (ReaxFF) will be incorporated to characterize the reaction pathways that take place in various SEIs. These tools will also be used to find ILs that suppress the growth of dendrites at the electrodes because they lead to formation of a more uniform SEI, which improves the cycling behavior. Furthermore, the effect of the aqueous electrolyte, which has been used in experiments, on the structure of the electrolyte at IL-electrode interface and its impact on the charge storage ability are open questions that will be addressed in my future research.

Devise polymerised-ILs that improve ion transport in the fuel cells: In proton exchange membrane fuel cells (PEMFCs), the platinum catalyst is poisoned by carbon monoxide in the hydrogen feed and the addition of the extra pure hydrogen significantly increases the cost of the process. Poisoning of the platinum catalyst can be reduced by elevating the temperature above 140ËšC. However, this reduces the efficiency of the PEMFCs due to the reduction in proton conductivity. Protic ILs can be combined with different polymers to enhance the ionic strength of the electrolyte, interfacial stability, and inflammability. Furthermore, various polymerised-IL electrolytes can be designed to meet specific requirements of the fuel cells electrolytes. In order to design and optimize a new generation of electrolytes, a detailed understanding of the nano- and microscale properties of the hybrid membranes is required. With this goal in mind, the volumetric, structural and dynamic properties of the membranes composed of different types of IL, IL/polymer mixture, and polymerised-IL electrolytes will be characterized.

Devise polymerised-ILs that improve ion transport in the fuel cells: In proton exchange membrane fuel cells (PEMFCs), the platinum catalyst is poisoned by carbon monoxide in the hydrogen feed and the addition of the extra pure hydrogen significantly increases the cost of the process. Poisoning of the platinum catalyst can be reduced by elevating the temperature above 140ËšC. However, this reduces the efficiency of the PEMFCs due to the reduction in proton conductivity. Protic ILs can be combined with different polymers to enhance the ionic strength of the electrolyte, interfacial stability, and inflammability. Furthermore, various polymerised-IL electrolytes can be designed to meet specific requirements of the fuel cells electrolytes. In order to design and optimize a new generation of electrolytes, a detailed understanding of the nano- and microscale properties of the hybrid membranes is required. With this goal in mind, the volumetric, structural and dynamic properties of the membranes composed of different types of IL, IL/polymer mixture, and polymerised-IL electrolytes will be characterized.

New computational methods for ionic liquids: Studying these problems using simulations requires significant computational time due to the atomistic and charged nature of the systems. To tackle this challenge I will develop a new simulation method to speed up the electrostatic computations. Coarse-grained models of ILs in a single phase that reduces the number of charge interaction points will increase the efficacy of the simulations. For simulations of electrodes at a constant electrical potential in presence of ILs, the electrodes will be treated with a fixed uniform surface charge density with no explicit atomic sites, which will decrease the computation time.

Teaching Interests:

I am excited to teach any core course in the undergraduate curriculum of chemical engineering, and I want to develop graduate elective courses on simulation. I will develop an interactive teaching method for students through using a computer-based teaching method. Using programming languages such as Julia and C++, students will learn how to apply different computational tools to solve not only problems that they face in the class, but also various intricate modeling problems that emerge in chemical engineering.

In particular, I look forward to teaching numerical analysis, process control and design courses that involve mathematical modeling and simulation. An advanced project-based course that covers molecular and Monte-Carlo simulations with a focus on complex fluids, such as ILs and biomolecules will be created as an elective course.

Research Background:

I have been fortunate to work on various research topics during my graduate studies in the Khare research lab at Texas Tech University. I started my graduate research by investigating the structural and rheological properties of dilute polymer solutions of different chain architectures. Later on, I created rigorous atomistically-detailed models for determining the volumetric, structural, and rheological properties of neat and polymer modified asphalts. Specifically, I showed that master curve can be constructed from simulation values of viscoelastic properties, thus this increases the range of time and frequency scales accessible to simulations by a few decades and facilitates a comparison with experiments. In addition, the simulations were able to capture the sub-glass transition temperature relaxation of the model structures that has been reported in experimental studies of glass former liquids. I have also closely collaborated with an experimental group in order to develop novel polymeric materials that can be utilized as the membrane in pervaporation applications. During the latter project, I demonstrated that the dynamics of solvent molecules (water and ethanol) are closely correlated with dynamics of cross-linked polymer regardless of the solvent concentration and this dynamic coupling could be used as an additional factor in designing polymeric materials for pervaporation based separations. In addition, in a collaborative study (Zhang et al., J. Phys. Chem. B, 2015, 119 (47)), we showed that MD simulations can capture the experimental trend of the viscosity of imidazolium-based ILs and is able to connect the macroscopic properties to the microstructure of ILs.

During my post-doctoral appointment in the Bonnecaze research group at the University of Texas at Austin, I am developing models and simulations of magnetically-driven flows of dilute suspensions of magnetite particles. In this study, we aim to model and simulate the drug delivery to a fully occluded blood vessel using a magneto-rheological fluid that is caused by a rotary magnetic field with a gradient. I also study the rheological properties of soft particle glasses. In particular, I found that the polydispersed soft particles glasses, which are jammed beyond the random close packing volume fraction, can form crystalline structures in the presence of shear flow. I am also creating atomistic models to study the interface of calcite and water in the presence of oil and surfactant molecules. This project is of interest to oil recovery applications in which the interfacial properties of a reservoir play a crucial role in determining the efficiency of the process.

In summary, I will apply these skills (atomistic and coarse-grained MD simulations of polymers/ionic liquids, microscale simulations of suspensions, and continuum mechanics) to other problems in the field of engineering to understand the mechanisms underlying different phenomena that occur at nano- and micro-length scales.