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Structural characterization of poly(diethylsiloxane) in the crystalline, liquid crystalline and isotropic phases by solid‐state 17 O NMR spectroscopy and ab initio MO calculations
Author(s) -
Kimura Hideaki,
Kanesaka Sho,
Kuroki Shigeki,
Ando Isao,
Asano Atsushi,
Kurosu Hiromichi
Publication year - 2005
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/mrc.1527
Subject(s) - chemistry , ab initio , phase (matter) , nuclear magnetic resonance spectroscopy , carbon 13 nmr satellite , ab initio quantum chemistry methods , crystallography , liquid crystal , electric field gradient , nmr spectra database , solid state nuclear magnetic resonance , isotropy , analytical chemistry (journal) , computational chemistry , nuclear magnetic resonance , fluorine 19 nmr , molecule , spectral line , organic chemistry , materials science , electric field , physics , optoelectronics , quantum mechanics , astronomy
The structure of poly(diethylsiloxane) (PDES) has been characterized using solid‐state NMR of 17 O. The sample studied had a weight‐average molecular weight of 2.45 × 10 5 . The sample was prepared by utilizing the cationic ring‐opening polymerization of 17 O‐enriched hexacyclotrisiloxane. Solid‐state NMR of 17 O‐enriched PDES was measured on the low‐temperature β 1 phase, the high‐temperature β 2 phase, the two‐phase system consisting of the liquid crystal and isotropic liquid phase and the isotropic phase. From these data, the molecular structure and dynamics of PDES in the various phases were characterized via the chemical shifts of 17 O, and electric field gradient parameters were determined from NMR and ab initio molecular orbital (MO) calculations. In addition to the solid‐state NMR of 1 H, 13 C and 29 Si previously reported on these samples, knowledge of the dynamic behavior of PDES as inferred from the NMR of 17 O in the present study was enhanced significantly. Further, the potential of combining the experimental NMR of 17 O with ab initio MO calculations to characterize the dynamics of polymers containing oxygen is demonstrated. Copyright © 2004 John Wiley & Sons, Ltd.