Introduction

    Synthetic polymers have a wide range of commercial applications, from plastic forks to automobile parts, resulting in a multibillion dollar industry. The specific use of a given polymer naturally depends on its physical properties - stress/strain behavior, chemical/thermal stability - which, in turn, depend on the structural details of the polymer chain. These details include molecular weight distribution, stereochemistry or tacticity of the polymer chain, end groups, branching or grafting points, types and sequences of copolymers, and geometrical features such as bond and dihedral angles.
    Most structural studies of polymers are performed using NMR spectroscopy or X-ray crystallography. One practical problem, however, is that polymers come in a distribution of sizes rather than as single entities. Most traditional methods of structural characterization often give only averaged conformational data. Any information on individual oligomers is impossible to obtain.
    Mass spectrometry has been shown to be an effective tool for characterizing the structures of synthetic polymers in the gas phase - most notably obtaining molecular weight distributions and identifying end groups and copolymer components. One advantage of mass spectrometry is that it can separate the polymer into its individual oligomer components. By combining our ion mobility methods with mass spectrometry, we can obtain conformational data about the polymer one oligomer at a time and observe details not readily available in the more traditional methods of structural characterization. We have used MS/ion mobility methods to investigate the gas-phase conformations of a number of synthetic polymers including:

• Polyethers - PEG, PPG, PTMEG
• PMMA & PS
• PET

Bowers group members who have worked on these projects include

• Jennifer Gidden
• Thomas Wyttenbach
• Michael T. Bowers