In this project, funded by the Chemical Measurement and Imaging Program of the Chemistry Division, Professor Chrys Wesdemiotis of the University of Akron and his group will develop new mass spectrometry techniques for the characterization of synthetic polymers. Tandem mass spectrometry studies involving collision-activated as well as electron-transfer dissociation will be performed on a variety of copolymers with the goal to elucidate the corresponding fragmentation pathways and evaluate the information they reveal about copolymer microstructure and sequence. A further goal is to create interfaced separation/mass spectrometry strategies for the analysis of multi-component polymer mixtures. Specifically, interactive liquid chromatography will be examined for the characterization of amphiphilic blends, and ion mobility mass spectrometry for the identification of polymer architectures, in particular the structures of supramolecular polymers.
A major impetus for the planned studies is the need of precise and sensitive chemical analyses for the new macromolecular materials designed and produced for industrial, clinical, and biomedical use at the University of Akron and several corporations in Northeast Ohio. The methods developed in this project will help to engineer better, commercially viable materials for a wide variety of applications. In addition, the planned research will educate and train undergraduate, graduate and post-graduate researchers, including students from underrepresented groups, in materials research and mass spectrometry analysis, two areas of increasing employment opportunities both locally and nationally.
The principal goal of this project was the development and optimization of mass spectrometry (MS) techniques, interfaced with separation methods, for the characterization of synthetic polymers. A major impetus for the studies performed was the need for precise and sensitive chemical analyses of the new macromolecular materials designed and produced at the University of Akron and its industrial partners in Northeast Ohio for industrial, clinical, biomedical, and technological applications. Fundamental 2-D (tandem) mass spectrometry studies have been performed on block, alternating, tapered, and random copolymers with different end groups, in order to elucidate the corresponding degradation pathways and the information revealed by them about the precise structures of the copolymers. Fragmentation was induced by both collisional heating as well as ion-ion reactions to establish the most suitable approach for a straightforward structural diagnosis. Using these methods, sensitive protocols were established for the analysis of polymer architectures and sequences, which must be known in order to correlate chemical structure with the resulting physical properties and design polymers for specific applications. This project also optimized hyphenated separation - mass spectrometry methods for the analysis of complex, multi-component polymer mixtures. These studies showed that liquid chromatography-mass spectrometry (LC-MS) affords complete separation of amphiphilic blends according to their constituent polarities, while ion mobility mass spectrometry (IM-MS) is ideally suitable for the separation and identification of isomeric polymer architectures and labile polymers, in particular the structures of supramolecular polymers. A new mass spectrometry protocol has been introduced for the analysis of materials that cannot be purified; it is called "top-down multidimensional mass spectrometry" and involves complete characterization inside the mass spectrometer by a combination of IM-MS and 2-D MS experiments. A new method for probing surface concentration has been developed to characterize the surface composition of polymer blends, which depends on both segregation and environmental factors. In parallel studies, the noncovalent complexes of oligonucleotides and cationic polymers were examined to gain information about the stoichiometries and relative stabilities of such species, which are used in gene transfection studies. An important finding of these studies is that the polymer components can be tuned to bind (and transport) either a specific nucleotide sequence or, unselectively, many different sequences. A large number of polymer and biomaterials companies are located in Northeast Ohio. Direct, strong collaborations between this community and the University of Akron take place, through which the mass spectrometry methods advanced in this project have been accessible to local industrial colleagues, facilitating the analysis of their polymers. These interactions have also familiarized the students participating in this project with industrial processes and the analytical questions arising in the manufacture and engineering of commercial polymers. Forty-five peer-reviewed publications (including one peer-reviewed book chapter), ten Ph.D. dissertations, twelve invited seminars, and thirty-four contributed talks or posters have resulted from this project. Participants included one postdoctoral fellow, ten graduate students (three male and seven female, including one African American male and one Puerto Rican American female), fifteen undergraduate students (nine male and six female, including one African American male and one African American female), and four high school students (one male and three female, including two African American females). These group members were trained in polymer and materials science, analytical separations, gas phase ion chemistry, and chemical analysis by mass spectrometry. They learned about fundamental chemistry concepts, especially those pertinent to the synthesis of the polymers and materials investigated and, at the same time, gained experience in mass spectrometry, which is increasingly used to solve analytical problems across many disciplines; this knowhow helped the project participants to secure employment after leaving the group (postdoc and Ph.D. graduates) or to continue with graduate or college studies (undergraduate and high school students, respectively).
