Positive mode electrospray tandem mass spectrometry of poly(methacrylic acid) oligomers

Giordanengo, Rémi; Viel, Stéphane; Allard-Breton, Béatrice; Thevand, André; Charles, Laurence

doi:10.1002/rcm.4040

Cited by 23 publications

(22 citation statements)

References 44 publications

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“…The homopolymer was detected with low intensity as [P n Ϫ H] Ϫ ions, with n the polymerization degree, but also as deprotonated molecules with some sodiated carboxylic acid groups, [P n ϩ xNa Ϫ (x ϩ 1)H] Ϫ ions (with x ranging from 1 to 3. Similar adducts were also formed from polymeric impurities, present in the studied standards, noted P= n and PЉ n in the inset of Figure 1a, consisting of a PMAA homopolymer with respectively one and two MMA unit, as evidenced in previous studies [29,30]. Mass spectra consisting of such multiple distributions, which have already been reported for poly(acrylic acid) or poly(styrene sulfonic acid) polymers [38], were obtained for all tested PMAA standards and a quite high laser fluence was usually required to generate the observed signals.…”

Section: Resultssupporting

confidence: 83%

Analytical strategy for the molecular weight determination of random copolymers of poly(methyl methacrylate) and poly(methacrylic acid)

Giordanengo

Viel

Hidalgo

et al. 2010

J. Am. Soc. Mass Spectrom.

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Molecular weight characterization of random amphiphilic copolymers currently represents an analytical challenge. In particular, molecules composed of methacrylic acid (MAA) and methyl methacrylate (MMA) as the repeat units raise issues in commonly used techniques. The present study shows that when random copolymers cannot be properly ionized by MALDI, and hence detected and measured in MS, one possible analytical strategy is to transform them into homopolymers, which are more amenable to this ionization technique. Then, by combining the molecular weight of the so-obtained homopolymers, as measured by MS, with the relative molar proportion of the MMA and MMA units, as given by 1 H NMR spectrum, one can straightforwardly estimate the molecular weight of the initial copolymer. A methylation reaction was performed to transform MAA-MMA copolymer samples into PMMA homopolymers, using trimethylsilyldiazomethane as a derivatization agent. Weight average molecular weight (M w ) parameters of the MAA-MMA copolymers could then be derived from M w values obtained for the methylated MAA-MMA molecules by MALDI, which were also validated by pulsed gradient spin echo (PGSE) NMR. An alkene function in one of the studied copolymer end-groups was also shown to react with the methylation agent, giving rise to MMA-like polymeric by-products characterized by tandem mass spectrometry and which could be avoided by adjusting the amount of the trimethylsilyldiazomethane in the reaction medium. (J Am Soc Mass Spectrom 2010, 21, 1075-1085) © 2010 American Society for Mass Spectrometry P olymers based on weak acids such as poly-(methacrylic acid) (PMAA) have attracted considerable attention because of the ability of the system to change strongly upon variations in the pH and ionic strength of the solution [1]. For example, amphiphilic PMAA-based block copolymers were reported to efficiently adsorb uranyl ions [2] or to selfassemble to produce dynamic micelles sensitive to different stimuli [3][4][5][6]. In particular, block copolymers containing PMAA and poly(methyl methacrylate) (PMMA) segments were the subject of intensive research activities [7][8][9][10]. However, interesting properties were also demonstrated for copolymers containing random MAA-MMA segments [11][12][13][14]. Performance of such materials highly depends on structurally-related parameters but also on molecular weight distribution.Determination of molecular weight parameters is not a trivial task for copolymers. Liquid state nuclear magnetic resonance (NMR) is the most commonly used technique for this purpose but only allows the number average molecular weight (M n ) parameter to be obtained. Size exclusion chromatography (SEC) requires calibration with narrow standards of the same chemical nature and structure as the analyte. Alternatively, one can use calibration which relies on Mark-HouwinkKuhn-Sakurada (MHKS) parameters being known for the standards and the analyte [15], since these parameters depend on both the nature of co-monomers and their relative proportion with...

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Section: Resultssupporting

confidence: 83%

Analytical strategy for the molecular weight determination of random copolymers of poly(methyl methacrylate) and poly(methacrylic acid)

Giordanengo

Viel

Hidalgo

et al. 2010

J. Am. Soc. Mass Spectrom.

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“…Alkali metal cationized poly(methacrylic acid) mainly fragments by sequential dehydrations (Giordanengo et al, 2009a). At low collision energies (up to $2 eV in the center-of-mass frame), the SCHEME 8. a: Charge-remote 1,5-H rearrangement in the t-butyl ester side chains of poly(t-butyl methacrylate) leading to the expulsion of isobutylene units.…”

Section: J Poly(methacrylic Acid) and Poly(acrylic Acid)mentioning

confidence: 99%

Fragmentation pathways of polymer ions

Wesdemiotis

Solak

Polce

et al. 2011

Mass Spectrometry Reviews

182

297

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Tandem mass spectrometry (MS/MS) is increasingly applied to synthetic polymers to characterize chain-end or in-chain substituents, distinguish isobaric and isomeric species, and determine macromolecular connectivities and architectures. For confident structural assignments, the fragmentation mechanisms of polymer ions must be understood, as they provide guidelines on how to deduce the desired information from the fragments observed in MS/MS spectra. This article reviews the fragmentation pathways of synthetic polymer ions that have been energized to decompose via collisionally activated dissociation (CAD), the most widely used activation method in polymer analysis. The compounds discussed encompass polystyrenes, poly(2-vinyl pyridine), polyacrylates, poly(vinyl acetate), aliphatic polyester copolymers, polyethers, and poly(dimethylsiloxane). For a number of these polymers, several substitution patterns and architectures are considered, and questions regarding the ionization agent and internal energy of the dissociating precursor ions are also addressed. Competing and consecutive dissociations are evaluated in terms of the structural insight they provide about the macromolecular structure. The fragmentation pathways of the diverse array of polymer ions examined fall into three categories, viz. (1) charge-directed fragmentations, (2) charge-remote rearrangements, and (3) charge-remote fragmentations via radical intermediates. Charge-remote processes predominate. Depending on the ionizing agent and the functional groups in the polymer, the incipient fragments arising by pathways (1)-(3) may form ion-molecule complexes that survive long enough to permit inter-fragment hydrogen atom, proton, or hydride transfers.

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“…In some cases, however, MS/MS experiments do not allow end-group analysis because polymer ion dissociation mainly proceeds via reactions involving pendant groups, such as for sodiated poly(methacrylic acid) [2], deprotonated poly(methacrylic acid) [3], or protonated poly(methyl methacrylate) [4]. The choice of the cation to be adducted to polymer molecules was also shown to have a great impact in the production of informative fragment ions under CID conditions.…”

Section: Introductionmentioning

confidence: 99%

Tandem Mass Spectrometry of Trimethylsilyl-Terminated Poly(Dimethylsiloxane) Ammonium Adducts Generated by Electrospray Ionization

Fouquet

Humbel

Charles

2011

J. Am. Soc. Mass Spectrom.

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Ammonium adducts of trimethylsilyl-terminated poly(dimethylsiloxane) (CH 3 -PDMS) produced by electrospray ionization were submitted to collision induced dissociation and revealed a particular MS/MS behavior: the same three main product ions at m/z 221, 295, and 369 were always generated in very similar relative abundances regardless of the size of the precursor ion. Combining accurate mass measurements and ab initio calculation allowed very stable cyclic geometries to be obtained for these ionic species. Dissociation mechanisms were proposed to account for the three targeted ions to be readily generated in a two-step or a three-step reaction from any CH 3 -PDMS ammonium adducts. A second set of three product ions was also observed with low abundance at m/z 207, 281, and 355, which were shown in MS 3 experiments to be formed in secondary reactions. An alternative dissociation process was shown to consist of a concerted elimination of ammonia and methane and the need for a methyl of an end-group to be involved in the released methane molecule would account for this reaction to mainly proceed from the smallest precursor ions.

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Positive mode electrospray tandem mass spectrometry of poly(methacrylic acid) oligomers

Cited by 23 publications

References 44 publications

Analytical strategy for the molecular weight determination of random copolymers of poly(methyl methacrylate) and poly(methacrylic acid)

Analytical strategy for the molecular weight determination of random copolymers of poly(methyl methacrylate) and poly(methacrylic acid)

Fragmentation pathways of polymer ions

Tandem Mass Spectrometry of Trimethylsilyl-Terminated Poly(Dimethylsiloxane) Ammonium Adducts Generated by Electrospray Ionization

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