Douglas M. Fox

Assistant Professor - E-mail - Curriculum vitae (pdf)

Research Summary:
Environmental Physical Chemistry & Polymer Nancomposites—CHEM490 Syllabus (pdf)

Current Research:
The growing world demand for crude oil and petroleum-based products is putting undue pressure on our ecosystem and has increased the need for more environmentally benign processes and products. To address this issue, our group focuses on measuring physicochemical properties of alternative (or “green”) solutions and polymer nanocomposites. Our lab is currently working on three main projects: green solvents and their solutions, ionic liquid – polymer gel electrolytes, and polymer nanocomposites. The majority of work is conducted on the campus of American University; however, some measurements must be acquired in collaboration with groups at the National Institute of Standards and Technology in nearby Gaithersburg, MD.

Green Solvents
A crucial step in the development of industrial processes with fewer environmental impacts is the characterization of environmentally benign or “green” solvents and their solutions. Today, much of the design and optimization of chemical processes is accomplished through the use of predictive methods and estimations of the required mixture properties. However, the accuracy of the simulated results depends on high quality and reliable thermophysical property data, which are often missing or incomplete. We address this issue by measuring the physical, electrical, and thermal properties of systems containing alternative solvents. The majority of recent work has focused on room temperature ionic liquids (ILs) and biodiesel, though systems containing ethyl lactate and terpenes are planned for the near future. Physical property measurements include densities, speed of sound, viscosities, surface tensions and solubilities. Electrical properties focus on conductivities, dielectric measurements, and cyclic voltammetry. Thermal properties include vapor-liquid equilibria using GC headspace analysis, melting characteristics using DSC and thermal stabilities using TGA.

Polymer Gel Electrolytes
Polymer Gel Electrolytes (PGEs) have gained significant attraction in recent years because they combine the improved safety, structure, and stability offered by solid polymer electrolytes while minimizing the conductivity loss compared to conventional liquid electrolytes. Furthermore, these gels can be designed as proton-, lithium-, or other cation-based battery electrolytes. The recent use of ionic liquids in place of nonaqueous solvent based electrolytes has further improved the safety and stability of the electrolytes, but can lead to reduced conductivity. In our labs, we examine the incorporation of nanoparticles into ionic liquid – polymer gel electrolytes (ILPGEs) and their impact on the overall battery performance. Emphasis is place on the interfacial properties and transport mechanisms involved in these novel materials. The gels are analyzed using a suite of measurements, including conductivity, DSC, FTIR, and DMA.

Polymer Nanocomposites
The incorporation of nano-dispersed particles into polymers can greatly improve their qualities, including their thermal, mechanical, barrier, and electrical properties. We focus our work on the incorporation of environmental friendly nanoparticles for reducing the flammability hazards of commodity plastics. These nanoparticles, such as clay, cellulose, and carbon nanofibers, often require chemical modifications to improve their miscibility with the polymers. In our lab, we predominantly use ionic liquid or polyhedral oligomeric silsesquioxane (POSS) based modifiers. Most of the experimental work for this project is conducted at NIST in collaboration with the Fire Research and Materials and Construction Research Divisions in the Building and Fire Research Laboratories. Paid summer research at NIST is often offered to undergraduate students working on this project.

Recent relevant publications
(1) D. M. Fox, J. W. Gilman, A. B. Morgan, J. R. Shields, P. H. Maupin, R. E. Lyon, H. C. De Long, and P. C. Trulove, “Flammability and Thermal Analysis Characterization of Imidazolium Based Ionic Liquids,” Ind. Chem. Eng. Res., in press.

(2) D. M. Fox, P. H. Maupin, S. Bellayer, M. Murariu, R. H. Harris Jr., J. W. Gilman, D. V. Eldred, D. Katsoulis, P. C. Trulove, and H. C. De Long, “Use of a polyhedral oliomeric silsesquioxane (POSS) – imidazolium cation as an organic modifier for montmorillonite,” Langmuir, 2007, 23, 7707-7714.

(3) R. A. Mantz, D. M. Fox, J. M. Green III, P. A. Fylstra, S. Bellayer, J. W. Gilman, P. C. Trulove, and H. C. De Long, “Dissolution of Biopolymers Using Ionic Liquids,” Z. Naturforsch. A, 2007, 62, 275-280.

(4) W. H. Awad, J. W. Gilman, M. Nyden, R. H. Harris, Jr., T. E. Sutto, J. H. Callahan, P. C. Trulove, H. C. De Long, and D. M. Fox, “Thermal degradation studies of alkyl-imidazolium salts and their application in nanocomposites,” Thermochim. Acta, 2004, 409, 3-11.

(5) D. M. Fox, W. H. Awad, J. W. Gilman, P. H. Maupin, H. C. De Long, and P. C. Trulove, “Flammability, thermal stability, and phase change characteristics of several trialkylimidazolium salts,” Green Chem., 2003, 5, 724.