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Mass Spectrometry Methods For Macromolecules: Polymer Architectures, Cross-Linking, and Surface Imaging

Endres, Kevin J
http://orcid.org/0000-0002-0857-6966
http://rave.ohiolink.edu/etdc/view?acc_num=akron1553096604194835

Abstract Details

2019, Doctor of Philosophy, University of Akron, Polymer Science.
This dissertation describes the development of novel mass spectrometry (MS) methodologies and techniques to improve, simplify and allow for specific characterizations of synthetic materials. Successful MS analyses are governed by the mass spectrometry principles surrounding specific ionization sources, mass analyzers and ion detecters. The methods described within this dissertation provide information about polymer materials that is historically difficult to determine using other available analytical techniques. Self-assembled terpyridine (tpy)-based metallomacrocycles that are coordinatively-bound using various transition metals were investigated through the analysis of their collision cross-section (CCS) values obtained by travelling wave ion mobility (TWIM)-MS separation, and through comparison to modeled/simulated structures and theoretical CCS values. This work demonstrated the uniquely powerful ability of TWIM-MS separation for architectural verification in samples containing stoichiometrically-defined isobaric ion species ranging from dimeric macrocycles to hexameric macrocycles. Furthermore, TWIM-MS was utilized in a separate project which allowed for the development of a method to monitor concentration dependent supramolecular structural equilibria and conformational trends. Using the methodology in this work, equilibrium constants were derived from these data; this was illustrated for two equilibria concerning the self-assembly of a tpy-based ligand containing a flexible crown ether moiety with Zn2+ ions, and a tetrakisterpyridinyl ligand with Cd2+ ions, which have previously been shown to reversibly interconvert. Additionally, experimental CCS values were also derived from drift time measurements and compared with theoretical predictions for these complex self-assembled terpyridine-based supramolecules to provide insight into their size, stoichiometry and architecture. Parallel studies have focused on the development of methods that can obtain connectivity and compositional information about covalently cross-linked polymers. The atmospheric solids analysis probe (ASAP) ionization source has been combined with MS, tandem MS (MS/MS) and TWIM to create an effective top-down technique for the molecular characterization of the mentioned materials, which were utilized in this project to address persisting structural questions about synthetic polymer cross-linking microstructures. The structural insight gained from these studies was illustrated by the analysis of two hydrogels: 1) oxime cross-linked poly(ethylene glycol) (PEG) hydrogels formed from the click-reaction between 4-arm PEG star polymers with levulinamide or levulinic acid end group functionalities and 4-arm PEG star polymers with aminoxyacetaamide or aminooxyacetic acid end group functionalities, and 2) cross-linked poly(methacrylate) (PMA)-PEG hydrogels formed from PEGdimethacrylate (PEGDMA) polymerized via radical propagation in the presence of a lithium acylphosphazine (LAP) photoinitiator and ultraviolet (UV) light. Lastly, the design of a surface-specific imaging technique with a probing depth of <2 nm, surface-layer matrix-assisted laser desorption ionization mass spectrometry imaging (SL-MALDI-MSI) is described. This technique has been developed and utilized to detect and elucidate defects in poly(styrene) (PS) and poly(methyl methacrylate) (PMMA) films. There are four major advantages of SL-MALDI-MSI over other surface analysis techniques, which are: (1) high specificity, as only the selected mass is measured; (2) direct information of the intact macromolecule rather than ambiguous data from molecular fragments or elements that may lead to misidentification of molecules at the surface; (3) no need for any fluorescent tagging or isotopic labelling; and (4) the possibility to perform MS/MS experiments.
Chrys Wesdemiotis (Advisor)
Mark Foster (Committee Chair)
George Newkome (Committee Member)
Matthew Becker (Committee Member)
Kevin Cavicchi (Committee Member)
261 p.
Analytical Chemistry; Chemistry; Materials Science; Polymer Chemistry; Polymers
mass spectrometry; tandem MS; polymer; terpyridine self-assemblies; coordination; equilibrium; ion mobility; collision cross-section; surface layer MALDI; ASAP; pyrolysis; cross-linking; hydrogel; MALDI MS Imaging; sublimation; polystyrene; PEG; thin film

Recommended Citations

Citations

  • Endres, K. J. (2019). Mass Spectrometry Methods For Macromolecules: Polymer Architectures, Cross-Linking, and Surface Imaging [Doctoral dissertation, University of Akron]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=akron1553096604194835

    APA Style (7th edition)

  • Endres, Kevin. Mass Spectrometry Methods For Macromolecules: Polymer Architectures, Cross-Linking, and Surface Imaging. 2019. University of Akron, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=akron1553096604194835.

    MLA Style (8th edition)

  • Endres, Kevin. "Mass Spectrometry Methods For Macromolecules: Polymer Architectures, Cross-Linking, and Surface Imaging." Doctoral dissertation, University of Akron, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=akron1553096604194835

    Chicago Manual of Style (17th edition)

akron1553096604194835
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This open access ETD is published by University of Akron and OhioLINK.