Post-source decay fragment ion analysis of polycarbonates by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

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Eur. J. Mass Spectrom. 5, 133 - 143 (1999)

Post-source decay fragment ion analysis of polycarbonates by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

L. Przybilla, H.-J. Räder^* and K. Müllen
Max-Planck-Institut für Polymerforschung, Ackermannweg 10, D-55128 Mainz, .

ABSTRACT:

Post-source decay (PSD) experiments using a matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometer have been applied to the structural determination of polycarbonates. We investigated linear and cyclic structures of polycarbonates derived from bisphenol A and a linear and a cyclic polycarbonate derived from 4,4¢-dihydroxydiphenyl-3,3-pentane as well as a linear polycarbonate derived from bisphenol Z. The fragmentation behavior of these polycarbonates is similar to the mechanism proposed in the literature for electron impact and static secondary-ion mass spectrometry measurements, but depends on the substituents bound to the central carbon atom of the bisphenol unit. Knowing the fragmentation mechanism of polycarbonates, the PSD-MALDI mass spectrum of a linear chain allows the masses of both end groups to be infered. However, it is shown that variation of the substituent on the bisphenol unit has a strong influence on the fragmentation behavior, so that cleavage of the polymer backbone may be suppressed and the spectra are dominated by the loss of side chains.

Keywords: MALDI-TOF, post-source decay (PSD), fragment ion, fragmentation mechanism, GPC-fractionation, polycarbonate, end group analysis

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