The overarching goals of this project were primarily three-fold: 1) to generate new classes of hydrophobic ionic liquids with great surfactant properties and grease dissolving abilities, 2) to achieve a greater scientific understanding of the key ionic liquid mechanisms and process variables for degreasing processes, and 3) to evaluate the potential for degreasing systems based on ILs in comparison with conventional solvents. 

The work consists of 3 tasks: 1) synthesis and characterization of new ionic liquids, 2) studies of degreasing technology based on ionic liquids, and 3) optimization of degreasing technology based on ionic liquids. The new types of ionic liquids are explored to tailor the chemistry for capability for removal of grease while mitigating corrosion. Bench-scale testing of contaminant removal is conducted in an interactive manner with synthesis. Optimization of degreasing is conducted in small scale testing, with systems characteristic of Department of Defense (DoD) end-users. 

This project aimed to develop an affordable, non-hazardous ionic liquids-based degreasing technology that would meet unique component requirements for DoD systems. The objective is to explore new chemistries and processes based on ionic liquids (ILs) for degreasing solvents that can be used to replace current high-volatile organic compounds (VOCs) solvents. Key elements included:

• Development of ionic liquid chemistries that provide suitable characteristics for degreasing in applications relevant to the military.
• Characterization of performance, both in terms of contaminant removal and possibility for degradation of substrates.
• Evaluation of the viability of degreasing processes based on ILs, taking into account contaminant buildup, cleaner recycling, losses, and waste production.

The research team performed synergistically linked research to address the following fundamental technical questions:

1. Can IL cations and anions be exploited to generate new classes of hydrophobic ILs with enhanced surfactant nature as good degreasing solvents for applications relevant to the military?
2. Can ILs provide the required level of degreasing comparable to conventional solvents?
3. Can IL solvents be used in a cost-effective manner, with sustained degreasing efficiency, minimal losses, and acceptable waste generation?

Six aprotic ionic liquids with built-in surfactant nature have been synthesized and characterized. Effects of carbon chain length of ionic liquids’ anions and the nature of cations on degreasing efficiencies have been investigated. The potential for the ionic liquid to act as a solvent for the contamination on the metal surface in question is promising.

The project will benefit the DoD through the development of improved degreasing solvents based on ionic liquids, which addressed potential applications for ionic liquids: We achieved a greater fundamental understanding of the key ionic liquid mechanisms and process variables for degreasing processes. This improved understanding will support the transition of promising ionic liquids processes into use with DoD’s maintenance and manufacturing systems.