Curcumin is a versatile chemical. It is used in food, medicine and electrical engineering. Use of curcumin in medical fields has been concentrated on the treatment of cancer, but it is a traditional spice that has been used in food preparation for millennia. Curcumin has seldom been used in physics, and electronics. In fact, curcumin gained its importance for its under representing ligand suitable for holding metal ions suspended in an insulating matrix of organic polymer. It consists of two regions: The ¿¿¿¿--diketone moiety for holding the metal, and the phenol group for attaching to the organic polymer. Its electronics applications have been focused primarily on the conversion of light to electricity. The unmodified structure of curcumin is not stable enough for photoluminescence because of its severe absorption in 340 nm - 535 nm wavelength range. Surprisingly, modified curcumin structures proved to be photo stabile in the visible range of 420 nm - 580 nm. Recently it was reported that 0.6% efficient photovoltaic material can be achieved using curcumin. In addition, curcumin dyes are chemically stable and eco-friendly.
The project began with Dr. Butcher's, Department of Chemistry, Ohio University, suggestion that curcumin might serve as a means for making electrically conducting polymers. Initial work conducted by this research led to the investigation of photovoltaic properties of engineered curcuminated epoxy and ITO glass as a transparent electrode. No photovoltaic behavior was observed, but the changes in resistance noted that were sufficiently interesting to warrant detailed investigation. In the project, we used purified curcumin to prepare a novel copper doped curcuminated epoxy polymer and studied electrical properties at ambient temperature. The Design of Experiments method was applied to this study for the purpose of determining the significance of various constituents on the conductivity. Sixteen compositions were prepared and investigated using a Keithley 6517A electrometer remotely controlled by LabView driver. The studied material compositions systematically varied the concentrations of curcumin, Cu (0), Cu (1), and Cu (2) ions. The analysis of the polymer data proved interesting by revealing two modes of conductivity: electronic and ionic conductions, respectively. In addition, the polymer exhibits various internal conductivity mechanisms and conforms to the standard polymer conductivity models. It was found that developed polymer exhibited good electrical properties initially; however it "aged" rapidly. The results obtained for this novel, conducting polymer may inspire others to pursue making prototypes of organic data storage devices, memory circuits and future work on dye sensitized organic photovoltaic if the material stability and lifetime can be increased in the future.
The polymer samples were prepared under the guidance of Dr. Jared A. Butcher, Jr. and tested under the supervision of Dr. Wojciech M. Jadwisienczak.