The main focus of this proposal, funded by the Polymers Program of the Division of Materials Research and the Office of Multidisciplinary Activities of the Directorate for Mathematical and Physical Sciences, is to apply state-of-the-art multidimensional nuclear magnetic resonance (NMR) methods to the characterization of commercially important fluoropolymers. Over the past decade, sculpted excitation methods have been developed to tackle problems with broad spectral windows and collection of large proton nD-NMR datasets. These capabilities are now a feature of state-of-the-art instruments. The applicability of these NMR methods will be demonstrated for studying fluorine in the structures of important fluoropolymers being developed by DuPont. The materials to be studied include: Nafion® fluorinated ionomer or its precursor (used as proton exchange membranes in fuel cells); Krytox® perfluoro(polyalkyl ether) (used as performance lubricants in computer disk drives and aerospace applications); Tedlar® poly(vinyl fluoride) (used in high performance coatings for protection in architectural and extreme environments); and Teflon-AF® and Viton® fluoroelastomer (used in other applications requiring the unique properties and inertness of fluorinated materials). The unique expertise and resources present in the University of Akron (UA) NMR group and the groups at DuPont Central Research & Development (DCRD) are keys to the success of this project. The UA group has years of experience in applying nD-NMR to the characterization of polymers. The DCRD groups provides many interesting polymer structure problems having scientific and commercial significance, provide access to fluoropolymer synthesis and characterization facilities, and have expertise essential for understanding the polymer chemistry of the materials to be studied. The collaboration with an industrial partner assures that the results will be applied to commercially significant problems.
NON-TECHNICAL SUMMARY:
The main focus of this proposal involving collaboration between U. Akron and DuPont scientists is to apply state-of-the-art nuclear magnetic resonance (NMR) methods to study the structures of commercially important fluoropolymers being developed by DuPont. The materials to be studied include: Nafion® fluoropolymers, used in the construction of fuel cells); Krytox® fluoropolymers, which are used as lubricants in computer disk drives and in aerospace applications; Tedlar® fluoropolymers, which are used in high performance coatings in architecture and for protection in extreme environments; and Teflon-AF® and Viton® fluoroelastomers, which are used in applications requiring their unique properties and inertness. This collaboration with Dupont will assure that relevant problems will be studied at a fundamental scientific level and that the results will have commercial implications. After graduation, many of the students trained in this project will continue to apply their knowledge to studies in polymer science and related fields. The specific NMR expertise unique to the UA research group is important to industry, as it is the only academic group in the country to focus on advanced solution NMR studies in polymer science. Additionally, researchers at many companies and universities have made use of the unique capabilities at the UA to solve difficult research problems. This important resource will be maintained through continued funding of a strong NMR research group. The students to be initially assigned to this project are all from underrepresented groups.
Fluoropolymers are a class of extremely stable materials which are used to make components that are exposed to extremely harsh environments such as high temperature and corrosive chemical substances. They are also used to make components that must last the lifetime of the device in which they are used, either because their replace during the service life of the device would involve an enormous expense or a tremendous inconvenience. Examples of such circumstances include the shutdown of a plant to replace a key gasket or seal, and the need to replace satellite components after they are placed in earth orbit. In this project we have studied the chemical structures of a variety of materials related to Dupont products including Krytox® fluorinated oils which are used as lubricants in recording devices and in devices which operate at high temperatures; Viton® fluoropolymers which are used to make gaskets and seals for chemical and aerospace applications; and Tedlar® fluoropolymers which are used as backing material in photovoltaic applications. A material’s desirable and undesirable properties are related to the exact nature and number of structures present. These structures in turn are dependent on the exact conditions (temperature, concentration of starting materials, relative number of starting materials, reaction time, etc.) used for their preparation. If a useful material is prepared, it is desirable to determine the exact structures present in that material and the relative number of the different structures present. This information can then be used in the material’s testing to relate structures present to desirable properties, and in the preparation of the material to either reproduce a useful formula or to alter reaction conditions to make more of a desirable structure. In this project we have developed nuclear magnetic resonance (NMR) methodology for studying the structures and compositions of fluoropolymers. We have applied that methodology to the study of the three classes of materials described above. We have also studied some new materials that might become useful commercial products for the industry. The NMR methodology has been published along with extensive NMR spectroscopic data so that it can be used by all researchers in the field to analyze their materials. These data appear in approximately twenty papers which have been published or are about to be published. These methods are becoming the standard for doing both academic and industrial research in the field. Eight student, including 6 graduate and 2 undergraduate students have benefited from training received under this grant. Most of these students have already graduated and assumed positions in academic and industrial laboratories. These students in turn have trained hundreds of other researchers to use NMR spectroscopic methods to study materials.
