Mihaela C. Stefan - US grants

TECHNICAL SUMMARY:

This CAREER grant will allow the PI to launch an interdisciplinary research and education program at the interface between organic/polymer chemistry, materials science and semiconductor technologies. The overall objective of the proposed research is to establish a synthetic design protocol to generate semiconducting polymers with tunable structures and electronic properties. Benzodithiophene with phenylethynyl substituents and thienodipyrrole will be employed as building blocks for the synthesis of novel semiconducting polymers with tunable energy levels. Benzodithiophene monomers with phenylethynyl electron withdrawing substituents render the polymers a lower LUMO energy level. By contrast, thienodipyrrole monomers with increased donor ability will generate semiconducting polymers with a higher LUMO energy level. Intermediate energy levels can be obtained by copolymerization of monomers. The proposed 5-years research program targets the synthesis of the proposed monomers and their corresponding polymers, structural, morphological and opto-electronic characterization, and the testing of the materials in bulk heterojunction solar cells. The experimental data obtained from solar cell testing will be used to fine tune the structures of the monomers and semiconducting polymers. The research program will have an application driven approach, where students will gain expertise in organic/polymer synthesis, characterization, and semiconductor technologies. The PI will capitalize on prior experience in polymer science and organic electronics, but also expand skills in fabrication and testing of solar cells. The PI?s research program will naturally expand into its education component by training graduate and undergraduate students who will develop skills in synthetic chemistry and solar cell fabrication and testing.

NON-TECHNICAL SUMMARY

The pending global energy crisis requires the development of new technologies that exploit the potential of renewable energy sources, such as solar power. For example, inorganic semiconductor based photovoltaic technology has reached the performance of converting 30% of solar energy into electric power. Despite this good performance, inorganic photovoltaics based on existing crystalline silicon technology are still too expensive to compete with the conventional sources of electricity. While extensive research in the field of silicon-based, inorganic photovoltaics is expected to result in a decrease in their fabrication cost, organic photovoltaics developed by the PI?s group are viable alternatives for low cost, lightweight, large area and flexible solar panels. The proposed research will aim toward the production of novel organic semiconducting polymers with high performance in organic solar cells. This CAREER award will support the interdisciplinary training of graduate and undergraduate students at the interface between chemistry and materials science. The PI will work closely with the Chemistry Students Association at the University of Texas at Dallas to design workshop experiments using polymers. These workshops will be presented in science fairs in the DFW area. The PI is also participating in the highly successful Nanoexplorers Program at UTD which gives high-school students the opportunity to participate in summer research.

I/UCRC for Energy Harvesting Materials and Systems

1035042 Virginia Polytechnic Institute and State University; Daniel Inman
1035024 University of Texas, Dallas; Bruce Gnade

The Center for Energy Harvesting Materials and Systems ((CEHMS) will focus on recovery (harvesting) of unused energy from various sources such as radio and television towers, satellites and various portable electronics. Virginia Polytechnic Institute (VT) and the University of Texas, Dallas (UTD) are collaborating to establish the proposed center, with VT as the lead institution.

The proposal seeks a grant for a new multi-university Center for Energy Harvesting Materials and Systems to focus on energy harvesting approaches. The focus of research within this center will be to investigate a wide range of potential energy harvesting opportunities in power systems, human activity, industrial machines, vehicles, vibrating structures and other such sources. While the energy harvested in any one of the opportunities is small, the accumulation effect can be very significant. The proposed researchers have identified some unique and creative opportunities to assess the value and potential for harvesting energy that would otherwise be untapped. The research is important to the US and much of the world in efforts to capture new sources of energy. The reduction in dependence on foreign oil is always of significant value. The PIs have excellent credentials for conducting the research effort, and the involvement of a number of qualified researchers from the two collaborative universities is impressive. The proposal is very well written and the project descriptions are clear and well documented. The research tasks are appropriate and appear to be very well conceived.

The proposed Center has the potential to improve sustainability and profitability of US manufacturing firms by developing new technologies that will reduce energy consumption and harvest energy that is normally wasted. The proposal uses a diverse group of researchers to develop new technologies that can be used in developing new industries, new jobs, new products and new services in the future. The research team is made up of various ethnic and gender groups that have a variety of educational and professional experiences including minority and disadvantage groups. The technologies that are developed by this proposal have the potential to have a large economical impact by producing jobs in new industries and reducing the need for existing fossil fuels. The plan for involving underrepresented students and faculty in the center is very well presented and appropriate. The research program will enhance the already impressive infrastructure at the two universities. Because of the wide range of topics, the dissemination of the results will be primarily through publications and industry meeting. The students involved with the program will be well prepared to enter the workforce and provide additional technology transfer.

With this award from the Major Research Instrumentation Program (MRI) that is co-funded by the Chemistry Research Instrumentation Program (CRIF), Professor Mihaela Iovu from University of Texas Dallas and colleagues A. Dean Sherry, John Ferraris, Dennis Smith and Jung-Mo Ahn will acquire a 500 MHz NMR spectrometer equipped with two probes. The proposal is aimed at enhancing research training and education at all levels, especially in areas such as (a) polythiophene-CdSe blends for bulk heterojunction solar cells, (b) perfluorocyclobutyl (PFCB) polymers for proton exchange membrane (PEM) fuel cells and gas separation applications, (c) fluorovinylene aryl ether telechelic polymers for thermal chain extension and tandem crosslinking, (d) lanthanide complexes and polymers as metabolic sensors for Magnetic Resonance Imaging, and (e) development of peptidomimetics for treatment of diabetes mellitus.

Nuclear Magnetic Resonance (NMR) spectroscopy is one of the most powerful tools available to chemists for the elucidation of the structure of molecules. It is used to identify unknown substances, to characterize specific arrangements of atoms within molecules, and to study the dynamics of interactions between molecules in solution. Access to state-of-the-art NMR spectrometers is essential to chemists who are carrying out frontier research. The results from these NMR studies will have an impact in synthetic organic/inorganic chemistry, materials chemistry and biochemistry. This instrument will be an integral part of teaching as well as research.

This award supports the University of Texas at Dallas to acquire a state of the art X-ray diffraction tool for determination and understanding of the crystal structure of new materials in the fields of low power electronics, energy storage, superconductors, organic electronics, nanotechnology, flexible electronics, photovoltaics, optoelectronics, and environmental catalysts. Crystal structure plays a major role in each of these important applications as it determines the mechanical, toxicity, reactivity, and electronic properties of the new materials. The remarkable advances over the past half century in the fields of computing, engineering, medicine, and energy would not have taken place had it not been for the creation of "materials by design" that is only possible when the structure of materials and their correlation to material properties are well known. UT-Dallas has state of the art facilities for materials synthesis by a wide range of technologically relevant processes in addition to advanced characterization tools. Therefore, this new instrument, which allows a precise determination of the structure of materials grown by the PI, will allow them to study the effect of processing conditions on materials structure and, in turn, determine the materials properties. The instrument will also play a significant role in the education of graduate and undergraduate students in a wide range of disciplines; it will be open to users from outside of the university fostering new collaborations in the Dallas-Fort Worth metropole and around the country.

The instrument is a Rigaku SmartLab high-resolution, ultra-high speed X-ray diffractometer for the structural analysis and crystal quality determination of bulk and thin-film organic and inorganic materials for nanoelectronic and energy applications. The new instrument will be housed in the Natural Science and Engineering Research Laboratory (NSERL) and will complement existing materials synthesis and device fabrication capabilities in dedicated labs and shared user facilities at UT-Dallas. The new diffractometer will significantly enhance in research high quality single crystal 2-dimensional semiconductors for high performance and low power nanoelectronic applications, in intermetallic and oxide layered materials that can exhibit a range of properties from unusual magnetism to superconductivity and more. In these fields and others the quantification of thin-film crystal quality and the orientation of grains in polycrystalline samples in reduced dimensions are crucial to understanding the process-structure-property relationships. The ability to determine crystal quality and carry out high-speed pole figures for texture analysis opens new research avenues for a wide number of investigators and students. The acquisition of a high-resolution and ultra-high speed X-ray diffractometer will greatly enhance the research of current and potential materials and device researchers within UT-Dallas and across the Dallas-Fort Worth Metroplex as well as dramatically transform important research and educational efforts. The instrument will be used to improve student education and training through hands-on access to new techniques and complement classroom learning.

NON-TECHNICAL SUMMARY:

The development of new technologies that exploit the potential of renewable energy sources such as solar power is currently one of the most targeted research directions. Polymer solar cells developed in the PI's research group at the University of Texas at Dallas (UTD) are being explored as feasible alternatives for low cost, lightweight, large area, and flexible solar panels. The proposed research will aim toward the synthesis and characterization of novel organic semiconducting polymeric materials with good performance in organic solar cells. Its overall objective is to establish a correlation between structure and opto-electronic properties for new types of semiconducting polymers. This award will support the interdisciplinary training of graduate and undergraduate students at the interface between chemistry, materials science, and semiconductor technologies. Other broader educational and diversity-enhancing impacts include mentoring of high school students over a one-year period to complete a science and engineering project. The PI is also participating in a highly successful program at UTD which gives high-school students the opportunity to participate in summer research.


TECHNICAL SUMMARY:

This project will allow the PI to extend and consolidate the interdisciplinary research and education program at the interface between polymer chemistry, materials science, and semiconductor technologies which she started through an NSF CAREER award. The overall objective of the proposed research is to establish a structure / opto-electronic properties correlation for benzodithiophene and benzodifuran donor-acceptor semiconducting polymers. Benzodithiophene and benzodifuran will be employed as building blocks for the synthesis of donor-acceptor polymers with tunable opto-electronic properties. The planned research program targets the synthesis of the monomers and their corresponding polymers, followed by their structural, morphological and opto-electronic characterization and the testing of the materials in bulk heterojunction solar cells. The experimental data obtained from solar cell testing will be used to fine-tune the structures of donor-acceptor semiconducting polymers. The research program will have a broadly integrated approach, where students will gain expertise in organic/polymer synthesis, characterization, and solar cell fabrication and testing. The PI will capitalize on prior experience in polymer science and organic electronics, but also expand skills in morphological characterization of the active layer of bulk heterojunction solar cells. The PI's research program will be tightly integrated with an education component by training graduate and undergraduate students who will develop expertise in organic/polymer chemistry, thin-film characterization, and solar-cell fabrication and testing. It will also be coupled with an outreach and diversity-enhancement program toward high-school students.

Professor Mihaela C. Stefan of the University of Texas at Dallas is supported by the Chemical Catalysis Program of the Division of Chemistry to develop polymerization catalysts based on neodymium (Nd) metal complexes. The objective is to provide research laboratories and the chemical industry with an alternative for the well-known Ziegler-Natta (ZN) catalyst system, which is widely used in industry for the preparation of polymers (large multi-unit molecules) from smaller molecules. The proposed Nd-based catalytic systems have the advantage of producing polymers from unusual starting materials, in reactions that are beyond the capabilities of current ZN catalysts. The versatile nature of the Nd-based catalytic system enhances the likelihood of success for the synthesis of stereoregular (highly ordered) polymers from different classes of small organic compounds. If successful, the project is likely to have immediate impact on the commercial production of polymeric materials, such as elastomers, adhesives and man-made fibers. Students working on the project are trained in organic and polymer synthesis and product characterization techniques. Female high school students are given the opportunity to participate in summer research to gain skills in a chemistry laboratory environment.

The objective of this research is to develop a novel catalytic system composed of NdCl3 and phosphate ligands for the polymerization of a variety of monomers, such as dienes, styrene and polar vinyl monomers. A mechanistic investigation of these polymerizations will be conducted to understand the function of each component and to optimize the reaction conditions for the production of polymers with high stereoregularity and well-defined molecular weights. The variation of the phosphate ligands around the Nd metal center is expected to influence the stereoregularity, molecular weights, and polydispersities of the synthesized polymers. The crystal structures of the synthesized neodymium catalysts is determined and correlated with their catalytic activity. The use of these catalysts for copolymerization of dienes with polar vinyl monomers demonstrates the versatility of the neodymium catalytic systems. The ability to polymerize polar vinyl monomers is especially attractive because the conventional Ziegler-Natta catalysts are not active for polymerization of polar vinyl monomers.

The Macromolecular, Supramolecular and Nanochemistry Program in the NSF Division of Chemistry supports Professors Mihaela C. Stefan and Michael C. Biewer of the University of Texas at Dallas to develop biodegradable and biocompatible polymers. The polymers of interest contain both water-friendly (hydrophilic) and water repellent (hydrophobic) segments can assemble in water to form core-shell structures in which the water-insoluble molecules can be loaded. The most attractive property of these polymers is their degradation in water media making them environmentally friendly materials. The project provides training to graduate and undergraduate students in the synthesis and characterization of organic compounds and polymers. High school students are given the opportunity to contribute in a summer research project to learn skills in a chemistry laboratory environment.

The objective of this proposed research is to develop polycaprolactone amphiphilic block copolymers that are biodegradable, biocompatible, and thermoresponsive. The research team aims to control the thermoresponsivity of the amphiphilic block copolymers by varying the ratio between the hydrophilic oligoethylene glycol substituted polycaprolactone hydrophilic block and the hydrophobic polycaprolactone block. To understand the dependence of the degradation rate on the structure of the block copolymers and their composition, the team investigates the effects of changing the linkage of the substituent on the monomers from ether to thioether, and from ester to thioester, on the polymer degradation rate. In addition, investigation of the self-assembly of the synthesized amphiphlic polycaprolactone block copolymers is conducted to obtain a correlation between the molecular structure and the size of micelles.