Article

Degradation of RAFT polymers in a cyclic ether studied via high resolution ESI-MS: Implications for synthesis, storage, and end-group modification

  1. Till Gruendling1,2,†,
  2. Russell Pickford2,
  3. Michael Guilhaus2,
  4. Christopher Barner-Kowollik1,*

Article first published online: 9 OCT 2008

DOI: 10.1002/pola.23050

Issue

Journal of Polymer Science Part A: Polymer Chemistry

Journal of Polymer Science Part A: Polymer Chemistry

Volume 46, Issue 22, pages 7447–7461, 15 November 2008

Additional Information

How to Cite

Gruendling, T., Pickford, R., Guilhaus, M. and Barner-Kowollik, C. (2008), Degradation of RAFT polymers in a cyclic ether studied via high resolution ESI-MS: Implications for synthesis, storage, and end-group modification. J. Polym. Sci. A Polym. Chem., 46: 7447–7461. doi: 10.1002/pola.23050

Author Information

  1. 1

    Preparative Macromolecular Chemistry, Institut für Technische und Polymerchemie, Universität Karlsruhe (TH)/Karlsruhe Institute of Technology (KIT), Engesserstr. 18, 76128 Karlsruhe, Germany

  2. 2

    Bioanalytical Mass Spectrometry Facility, UNSW Analytical Centre, The University of New South Wales, Sydney, New South Wales 2052, Australia

  1. †

    Centre for Advanced Macromolecular Design (CAMD), The University of New South Wales, New South Wales 2052, Australia.

*Preparative Macromolecular Chemistry, Institut für Technische und Polymerchemie, Universität Karlsruhe (TH)/Karlsruhe Institute of Technology (KIT), Engesserstr. 18, 76128 Karlsruhe, Germany

Publication History

  1. Issue published online: 9 OCT 2008
  2. Article first published online: 9 OCT 2008
  3. Manuscript Accepted: 26 AUG 2008
  4. Manuscript Received: 11 JUL 2008

Funded by

  • University of Karlsruhe/Karlsruhe Institute of Technology (KIT)
  • Australian Research Council
  • University of New SouthWales

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Keywords:

  • degradation;
  • electrospray ionization mass spectrometry (ESI-MS);
  • ether peroxides;
  • living radical polymerization (LRP);
  • mass spectrometry;
  • polymer end-group degradation;
  • poly(methyl methacrylate) (PMMA);
  • polystyrene (PS);
  • reversible addition fragmentation chain transfer (RAFT)

Abstract

We report on the detailed mass spectrometric analysis of the degradation products generated during storage of poly(methyl methacrylate) (pMMA) and polystyrene (pSty) carrying cumyldithiobenzoate (CDB) endgroups. Samples were stored in either a cyclic ether (tetrahydrofuran) (THF) or an inert solvent (dichloromethane). The degradation process was followed over a period of 4-weeks. Degradation rate of the reversible addition fragmentation (RAFT) polymer strongly depends on the hydroperoxide-content of the solvent. Mass spectrometric evidence supports an unexpected radical degradation mechanism for the pMMA macroRAFT agent. Hydroperoxide functional pMMA was the single product after less than 7 days in high purity THF. No formation of the sulfine/thioester was observed. The identity of the hydroperoxide was unambiguously assigned using accurate mass measurements by Fourier-Transform ion-cyclotron-resonance mass spectrometry together with chemical identification reactions. The hydroperoxide end group formation proceeds efficiently as well as in high yields and thus constitutes a powerful method for end group modification. The degradation pathways of the CDB functional pSty in THF include mainly oxidation towards the sulfine/thioester, with little degradation via thermal elimination of dithiobenzoic acid and subsequent epoxidation. The shelf life of CDB functional polymers is limited even in inert solvent because of this inherent but slow thermal elimination reaction. Because of the short period necessary for the transformation of the functional dithiobenzyl endgroups, substitution of cyclic ethers as solvents for RAFT polymers in synthesis and analysis is strongly suggested. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 7447–7461, 2008

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