Poly(methyl methacrylate) and Poly(styrene)

    Tandem mass spectrometry (MS/MS) has long been used to provide additional structural information that is not readily available from single mass spectrometric analyses. In MS/MS experiments, the ion of interest is mass selected and then intentionally fragmented, via collisions with an inert gas (CID) or the ion may have enough internal energy to fragment on its own. The resulting fragments are then mass analyzed. For synthetic polymers, MS/MS experiments have been used to identify end groups, determine the sequence of copolymers, investigate the structures of monomers, etc.
    Two such polymers that have been characterized by MS/MS methods are poly(methyl methacrylate) PMMA and poly(styrene) PS.

These polymers don't appear to have much in common but they have very similar CID fragmentation spectra. Ion mobility measurements and molecular modeling calculations were used to determine the conformations and polymer-alkali cation binding properties to help explain the CID spectra and propose mechanisms for the fragmentation process.

More detailed information can be found in:

"Gas Phase Conformations of Synthetic Polymers: Poly (methyl methacrylate) Oligomers Cationized by Sodium Ions" Jennifer Gidden, Anthony T. Jackson, James H. Scrivens, and Michael T. Bowers Int. J. Mass Spectrom. 1999, 188, 121

"Gas-Phase Conformations of Cationized Poly(styrene) Oligomers" Jennifer Gidden, Michael T. Bowers, Anthony T. Jackson, and James H. Scrivens J. Am. Soc. Mass Spectrom. 2002, 13, 499