Elucidating Branching Topology and Branch Lengths in Star-Branched Polymers by Tandem Mass Spectrometry

  • Jialin Mao
  • Boyu Zhang
  • Hong Zhang
  • Ravinder Elupula
  • Scott M. Grayson
  • Chrys WesdemiotisEmail author
Focus: Honoring Helmut Schwarz's Election to the National Academy of Sciences: Research Article


Tandem mass spectrometry (MS2) has been employed to elucidate the topology and branching architecture of star-branched polyethers. The polymers were ionized by matrix-assisted laser desorption/ionization (MALDI) to positive ions and dissociated after leaving the ion source via laser-induced fragmentation. The bond scissions caused under MALDI-MS2 conditions occur preferentially near the core-branch joining points due to energetically favorable homolytic and heterolytic bond cleavages near the core and release of steric strain and/or reduction of crowding. This unique fragmentation mode detaches complete arms from the core generating fragment ion series at the expected molecular weight of each branch. The number of fragment ion distributions observed combined with their mass-to-charge ratios permit conclusive determination of the degree of branching and the corresponding branch lengths, as demonstrated for differently branched homo- and mikto-arm polyether stars synthesized via azide-alkyne click chemistry. The results of this study underscore the utility of MS2 for the characterization of branching architecture and branch lengths of (co) polymers with two or more linear chains attached to a functionalized central core.


Star-branched polymers Tandem mass spectrometry Polymer architecture Degree of branching Branch lengths 



Support from the National Science Foundation (grant CHE-1808115) is gratefully acknowledged.

Supplementary material

13361_2019_2260_MOESM1_ESM.docx (674 kb)
ESM 1 (DOCX 670 kb)


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Copyright information

© American Society for Mass Spectrometry 2019

Authors and Affiliations

  1. 1.Department of Chemistry, Knight Chemical LaboratoryThe University of AkronAkronUSA
  2. 2.Department of ChemistryTulane UniversityNew OrleansUSA

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