title: Ab initio calculations of possible γ-gauche effects in the ¹³C-NMR for methine and carbonyl carbons in precise polyethylene acrylic acid copolymers.
abstract: The impacts of local polymer chain conformations on the methine and carbonyl ¹³C-NMR chemical shifts for polyethylene acrylic acid p(E-AA) copolymers were predicted using ab initio methods. Using small molecular cluster models, the magnitude and sign of the γ-gauche torsional angle effect, along with the impact of local tetrahedral structure distortions near the carbonyl group, on the ¹³C-NMR chemical shifts were determined. These ¹³C-NMR chemical shift variations were compared to the experimental trends observed for precise p(E-AA) copolymers as a function acid group spacing and degree of zinc-neutralization in the corresponding p(E-AA) ionomers. These ab initio calculations address the future ability of ¹³C-NMR chemical shift variations to provide information about the local chain conformations in p(E-AA) copolymer materials.
authors.affiliation: Department of Nanostructured and Electronic Materials, Sandia National Laboratories, Albuquerque, NM 87185, USA. tmalam@sandia.gov
authors.forename: Todd M
authors.initials: TM
authors.lastname: Alam
mesh_terms: D000179:Acrylates / Q000737:chemistry; D002244:Carbon / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008968:Molecular Conformation; D020959:Polyethylene / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry*
chemical_list: D000179:Acrylates; D011108:Polymers; D002244:Carbon; D020959:Polyethylene; C036658:acrylic acid
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