CAMP Annual Report: Page 8
Novel Polymeric Materials
Professor Sitaraman Krishnan’s research group, in the Department of Chemical and Biomolecular Engineering, specializes in the synthesis of novel polymeric materials, and studying the thin film and surface properties of these materials. Current research projects in his group include ionic liquid and polymer electrolytes for dye-sensitized solar cells and lithium ion batteries, proton conducting polymer membranes for fuel cells, polymer solar cells using oriented conjugated polymer thin films, polymer–ceramic composite coatings for high-temperature and high-pressure applications, and pH-responsive polysaccharide microparticles as controlled-release oral delivery systems. The group has designed and synthesized a novel block oligomer ionic liquid that has an unusual combination of transport properties, namely low fluidity and high ionic conductivity, which they attribute to nanostructure formation via molecular self-assembly. Research on developing fuel cell membranes that can conduct protons at high temperatures is also underway. Conventional membranes, which rely on water for proton conduction, lose their functionality when used at high temperatures because of dehydration. The polysaccharide microparticles for sustained oral delivery of bioactive molecules have been designed to release materials selectively in the small intestine, without being affected by the highly acidic conditions in the stomach. The group has also developed ionic block copolymer coatings, with tunable surface charges, that show selective adsorption of protein molecules based upon electrostatic interactions.
Professor Krishnan collaborates with Professor Dipankar Roy, in the Physics Department at Clarkson University, with Professors John McLaughlin and Don Rasmussen in the Department of Chemical and Biomolecular Engineering, and with Professor John Moosbrugger in the Department of Mechanical and Aeronautical Engineering. The graduate and undergraduate student researchers working in his laboratory include Ms. Lin Wu, Ms. Janice Lebga, Ms. Azar Abidnejad, Mr. James Myrick, Mr. Joshua Franclemont, and Ms. Yarong Lin.
Professors Sitaraman Krishnan, Dipankar Roy, and John McLaughlin are performing research on ionic liquids (ILs) for several potential applications including photovoltaic cells and energy storage devices. A novel imidazolium iodide ionic liquid with a w-perfluoroalkyloly(ethylene glycol) (PEG) tail attached to the imidazolium ring has been synthesized for its potential incorporation as an electrolyte in dye-sensitized solar cells. Molecular self-assembly resulted in the formation of a solvent-free ionogel (an ionic solid), without the assistance of an external gelator or an immobilizing matrix. The process was facilitated by the generation of ionic clusters due to electrostatic interactions as well as microphase separation of the immiscible perfluoroalkyl and PEG segments of the cation. A paper has been submitted for publication that describes the synthesis and electrochemical properties of this block oligomer ionogel, along with illustrative results of self-consistent mean field calclations probing the formation of nanostructures in the ionogel. Although a high ionic conductivity appears incompatible with the high viscosity of such systems, the results reported in the paper show how this combination is accomplished for nano-structured electrolytes. Despite its low effective fludidity, this organic, the electrolyte can sustain strong diffusion of iodide ions.
Figure 3. Cylindrical regions that are rich in the fluoroalkyl component (on the right) are surrounded by regions with iodide (on the left).
The self-consistent field modeling provides a microstructural explanation for the combination of high viscosity and high electrical conductivity of the ILs. For the pure IL, the self-consistent mean field predicts a lamellar structure. When blended with another solid electrolyte, the microstructure changes to one in which cylindrical regions that are rich in the fluoroalkyl component are surrounded by regions in which the iodide anions and free cations can travel freely through a mixture of PEG and cationic head groups. See Figure 3 (left, iodide, and right, fluoroalkyl groups). The presence of elongated structures of fluorinated material qualitatively explains the cause of the large viscosity.
The experiments were carried out by Professor Krishnan’s graduate students, Lalitha V.N.R. Ganapatibhotla and Lin Wu and by Dr. Jianping Zheng (a graduate student in Professor Roy’s laboratory), who is now at GOBALFOUNDRIES. Dr. Xinli Jia worked with Professor McLaughlin on the self-consistent field modeling.
STATE-FUNDED RESEARCH PROJECTS
Nine research projects were supported by the Centers for Advanced Technology (CAT) Program of the Empire State Development Division of Science, Technology, and Innovation (NYSTAR) in the 2010 - 2011 fiscal year. Project titles and principal investigators are listed below for each research area.
- Chemical and Structural Analysis- R. Partch and D. Rasmussen
- Solar Rectenna Array Prototype Development- S. Krishnan
Thin Films and Coatings
- Free Form Fiber- S. V. Babu
- Thin Film development- S. V. Babu
- Concretes that Incorporate High Carbon Fly Ash and Foundry Sand Development and Performance Testing- N. Neithalath
- Development and Construction of a UCT System- C. Cetinkaya
- Tools for Analysis of Early Age Transverse Cracking of Composite Bridge Decks- K. Janoyan
- Innovative Bridge Research and Deployment Program- K. Janoyan
- Non-Reference Based Inertial Tracking System for Drifting Sensor Platform- K. Janoyan