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DNP NMR Studies of Crystalline Polymer Domains by Copolymerization with Nitroxide Radical Monomers

Version 2 2024-06-03, 19:48
Version 1 2018-11-27, 10:42
journal contribution
posted on 2024-06-03, 19:48 authored by E Verde-Sesto, N Goujon, H Sardon, P Ruiz, TV Huynh, F Elizalde, D Mecerreyes, Maria ForsythMaria Forsyth, Luke O'DellLuke O'Dell
Dynamic nuclear polarization (DNP) nuclear magnetic resonance (NMR) spectroscopy is increasingly recognized as a powerful and versatile tool for the characterization of polymers and polymer-based materials. DNP requires the presence of unpaired electrons, usually mono- or biradicals, and the method of incorporation of these groups and their distribution within the structure is crucial. Methods for covalently binding the radicals to the polymer and controlling their location (e.g., exclusively within a specific phase or at an interface) can allow the selective enhancement of a particular region or the measurement of domain sizes. We have prepared a series of polyurethanes by copolymerization of a nitroxide radical monomer with poly(ethylene glycol) (PEO) and diisocyanate linkers. The PEO is shown to form crystalline domains with the radical monomers in a separate phase, providing DNP enhancements of around 10 and allowing the domain size and morphology to be probed with the aid of X-ray scattering data. Additionally, electron paramagnetic resonance is used to estimate the inter-radical distances and density functional theory calculations are used to refine the PEO crystal structure.

History

Journal

Macromolecules

Volume

51

Pagination

8046-8053

Location

Washington, D.C.

ISSN

0024-9297

eISSN

1520-5835

Language

English

Publication classification

C1 Refereed article in a scholarly journal

Copyright notice

2018, American Chemical Society.

Issue

20

Publisher

AMER CHEMICAL SOC