In this project, Professors Vladimir Tsukruk and John Reynolds of Georgia Institute of Technology are supported by the Macromolecular, Supramolecular, and Nanochemistry (MSN) Program of the NSF to make new materials consisting of polymers combined with gold and silver nanometer-sized particles. Currently, novel color-changing materials made of plastic or polymers can be designed so that their colors can be tuned from purple to red and their transparency from absolutely clear to completely opaque. Flexible filters made from these polymers can block or deflect harmful short wavelengths (like those that cause sunburn) and transmit long wavelengths useful for sun-illuminated heating. Most of the filters known today are fixed for a particular function and cannot be changed after fabrication. It is possible to change the color and transparency of these filters using light, the chemical environment, or small applied electric fields. The potential uses of these novel structures are to facilitate intelligent light harvesting for flexible solar cells at dusk or dawn and to create wearable electronics that allow the continuous monitoring of the wearer's health. Further, this work has an impact in regard to chemistry education and teaching through the development of select in-house tutorials defining the fundamental aspects of conjugated polymer synthesis and electrochemistry that are required in order for one to be conversant in these technologies. A broader impact of this project is the enhanced training of graduate and undergraduate students with an emphasis on their early involvement in interdisciplinary, fundamental research with active recruitment of underrepresented groups. To broaden the scope of these efforts, webinar tutorials are developed and made available through a website that uses WIKI software for release to the general scientific community. This work impacts energy sciences, polymer and materials chemistry, electrochemistry, and organic electronics.
The merit of this cross-disciplinary study is the development of a fundamental understanding of the behavior and driving molecular mechanisms of electrochemically-driven transformations of macromolecules. These transformations affect the supramolecular organization, redox state, and the balance of electronic and ionic conductivities of macromolecules in proximity to inorganic interfaces. The various processes associated with electrochromic behavior are investigated utilizing a series of newly synthesized polymers deposited on metal interfaces. The work includes synthesis of novel water-soluble and processable conjugated polyelectrolytes with variations in band gap, color, and oxidation potential. The assembly of interfacial polymer layers around noble metal nanostructures balances local and global polymer chain conformation, charge, and redox potential distribution. These factors are critical for controlling the optical properties of the polymers including absorbance, refractive index, and plasmonic interactions during electrochemical oxidation. The broader impacts of this project include the involvement of students into cross-disciplinary, fundamental research and the dissemination of new skills and knowledge to the broader educational community through tutorial webinars.
