title: Successful MALDI-MS analysis of synthetic polymers with labile end-groups: the case of nitroxide-mediated polymerization using the MAMA-SG1 alkoxyamine.
abstract: A sample pretreatment was evaluated to enable the production of intact cationic species of synthetic polymers holding a labile end-group using matrix-assisted laser desorption/ionization (MALDI) mass spectrometry. More specifically, polymers obtained by nitroxide-mediated polymerization involving the MAMA-SG1 alkoxyamine were stirred for a few hours in trifluoroacetic acid (TFA) to induce the substitution of a tert-butyl group on the nitrogen of nitroxide end-group by a hydrogen atom. Nuclear magnetic resonance, electrospray ionization tandem mass spectrometry, and theoretical calculations were combined to scrutinize this sample pretreatment from both mechanistic and energetic points of view. The substitution reaction was found to increase the dissociation energy of the fragile C-ON bond to a sufficient extent to prevent this bond to be spontaneously cleaved during MALDI analysis. This TFA treatment is shown to be very efficient regardless of the nature of the polymer, as evidenced by reliable MALDI mass spectrometric data obtained for poly(ethylene oxide), polystyrene and poly(butylacrylate).
authors.affiliation: Aix-Marseille Univ-CNRS, UMR 7273, Institut de Chimie Radicalaire, Equipe Spectrométries Appliquées à la Chimie Structurale, 13397 Marseille, France.
authors.forename: Caroline
authors.initials: C
authors.lastname: Barrère
authors.forename: Christophe
authors.initials: C
authors.lastname: Chendo
authors.forename: Trang N T
authors.initials: TN
authors.lastname: Phan
authors.forename: Valérie
authors.initials: V
authors.lastname: Monnier
authors.forename: Thomas
authors.initials: T
authors.lastname: Trimaille
authors.forename: Stéphane
authors.initials: S
authors.lastname: Humbel
authors.forename: Stéphane
authors.initials: S
authors.lastname: Viel
authors.forename: Didier
authors.initials: D
authors.lastname: Gigmes
authors.forename: Laurence
authors.initials: L
authors.lastname: Charles