title: X-Band DNP Hyperpolarization of Viscous Liquids and Polymer Melts.
abstract: NMR studies of synthetic polymers and biomacromolecules, which provide insight into the conformation and dynamics of these materials, can benefit strongly from the increased sensitivity offered by dynamic nuclear polarization (DNP) and other hyperpolarizing methods. In this study (1) H DNP nuclear spin hyperpolarization of two polybutadiene samples, representing a supercooled liquid and an entangled polymer melt, is demonstrated at 0.35 T magnetic field strength and at temperatures between -80 and +50 °C. Electron spin polarization transfer from the α,γ-bisdiphenylene-β-phenylallyl radical to the sample nuclei is achieved by the Overhauser and solid effect. DNP signal enhancements are studied, varying the electron spin resonance offset, microwave power, and sample temperature. The influence of spin relaxation times, line widths, and molecular dynamics are discussed. The results show promising, up to 15-fold NMR signal enhancements using noncryogenic temperatures and an inexpensive setup that is less technically demanding than current high-field DNP setups.
authors.affiliation: Max Planck Institute for Polymer Research, Ackermannweg 10, 55128, Mainz, Germany.
authors.forename: Oliver
authors.initials: O
authors.lastname: Neudert
authors.affiliation: Max Planck Institute for Polymer Research, Ackermannweg 10, 55128, Mainz, Germany.
authors.forename: Miriam
authors.initials: M
authors.lastname: Reh
authors.affiliation: Max Planck Institute for Polymer Research, Ackermannweg 10, 55128, Mainz, Germany.
authors.forename: Hans W
authors.initials: HW
authors.lastname: Spiess
authors.affiliation: Max Planck Institute for Polymer Research, Ackermannweg 10, 55128, Mainz, Germany.
authors.forename: Kerstin
authors.initials: K
authors.lastname: Münnemann
mesh_terms: D002070:Butadienes / Q000737:chemistry*; D020724:Elastomers / Q000737:chemistry*; D005609:Free Radicals / Q000737:chemistry*; D010636:Phenols / Q000737:chemistry*; D066244:Proton Magnetic Resonance Spectroscopy / Q000379:methods*; D013696:Temperature; D044366:Transition Temperature; D014783:Viscosity
chemical_list: D002070:Butadienes; D020724:Elastomers; D005609:Free Radicals; D010636:Phenols; C028834:polybutadiene
keywords: NMR; dynamic nuclear polarization; hyperpolarization; polybutadienes; viscous liquids