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Up to 100% Improvement in Dynamic Nuclear Polarization Solid‐State NMR Sensitivity Enhancement of Polymers by Removing Oxygen
Author(s) -
Le Dao,
Ziarelli Fabio,
Phan Trang N. T.,
Mollica Giulia,
Thureau Pierre,
Aussenac Fabien,
Ouari Olivier,
Gigmes Didier,
Tordo Paul,
Viel Stéphane
Publication year - 2015
Publication title -
macromolecular rapid communications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.348
H-Index - 154
eISSN - 1521-3927
pISSN - 1022-1336
DOI - 10.1002/marc.201500133
Subject(s) - polymer , polystyrene , materials science , solvent , polarization (electrochemistry) , solid state nuclear magnetic resonance , oxygen , solid state , analytical chemistry (journal) , nuclear magnetic resonance , chemistry , organic chemistry , physics , composite material
High‐field dynamic nuclear polarization (DNP) has emerged as a powerful technique for improving the sensitivity of solid‐state NMR (SSNMR), yielding significant sensitivity enhancements for a variety of samples, including polymers. Overall, depending upon the type of polymer, the molecular weight, and the DNP sample preparation method, sensitivity enhancements between 5 and 40 have been reported. These promising enhancements remain, however, far from the theoretical maximum (>1000). Crucial to the success of DNP SSNMR is the DNP signal enhancement ( ε DNP ), which is the ratio of the NMR signal intensities with and without DNP. It is shown here that, for polymers exhibiting high affinity toward molecular oxygen (e.g., polystyrene), removing part of the absorbed (paramagnetic) oxygen from the solid‐state samples available as powders (instead of dissolved or dispersed in a solvent) increases proton nuclear relaxation times and ε DNP , hereby providing up to a two‐fold sensitivity increase (i.e., a four‐fold reduction in experimental time).