Electrospray ionization mass spectrometric study of oligomeric linear polysulfides: characterization of repeat units, end groups and fragmentation pathways

Abstract

Electrospray ionization mass spectrometry is shown to offer excellent characterization of linear oligomeric polysulfides H(SC 2H 4OCH 2OC 2H 4S) n H with n = 1–24. Analysis of the mass spectra reveals the presence of individual oligomers, the presence in certain oligomers of repeat units containing additional oxyalkylene groups (and in some cases a monosulfide link rather than disulfide) and the presence of end groups such as epoxy. The attachment of polyacrylates during cure can also be detected. Assignments of individual peaks can be confirmed by collision-induced decomposition and precursor ion experiments: the fragmentation pathways are relatively few except for linear polysulfides of complex structure. The best signal-to-noise conditions are achieved with low-to-medium cone voltages and a mobile phase of acetone containing 0.5% KI.