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Titolo:
Studies on different types of hydrogen bonds in poly(vinyl alcohol) films by H-1 CRAMPS and solid-state two-dimensional H-1-C-13 heteronuclear correlation analyses
Autore:
Masuda, K; Kaji, H; Horii, F;
Indirizzi:
Kyoto Univ, Inst Chem Res, Uji, Kyoto 6110011, Japan Kyoto Univ Uji KyotoJapan 6110011 st Chem Res, Uji, Kyoto 6110011, Japan
Titolo Testata:
POLYMER JOURNAL
fascicolo: 2, volume: 33, anno: 2001,
pagine: 190 - 198
SICI:
0032-3896(2001)33:2<190:SODTOH>2.0.ZU;2-H
Fonte:
ISI
Lingua:
ENG
Soggetto:
C-13 NMR ANALYSES; CORRELATION SPECTROSCOPY; CHAIN CONFORMATION; CHEMICAL-SHIFTS; TACTICITIES;
Keywords:
hydrogen bonding; chain conformation; poly(vinyl alcohol); crystal structure; cross polarization-magic angle spinning C-13 NMR; H-1 combined rotation and multiple pulse; spectroscopy; H-1-C-13 heteronuclear correlation spectroscopy;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
33
Recensione:
Indirizzi per estratti:
Indirizzo: Horii, F Kyoto Univ, Inst Chem Res, Uji, Kyoto 6110011, Japan Kyoto Univ Uji Kyoto Japan 6110011 es, Uji, Kyoto 6110011, Japan
Citazione:
K. Masuda et al., "Studies on different types of hydrogen bonds in poly(vinyl alcohol) films by H-1 CRAMPS and solid-state two-dimensional H-1-C-13 heteronuclear correlation analyses", POLYM J, 33(2), 2001, pp. 190-198

Abstract

Different hydrogen-bonded states of OH groups in poly(vinyl alcohol) (PVA)films with different tacticities have been characterized by H-1 combined rotation and multiple pulse spectroscopy (CRAMPS), solid-state C-13 NMR and two-dimensional (2D) H-1-C-13 heteronuclear correlation (HETCOR) analyses. The newly developed line shape analysis for the H-1 CRAMPS spectra reveals the existence of three types of OH groups in different hydrogen-bonded states below T-g intramolecular and intermolecular hydrogen bonded OH (OHintra,OHinter) groups and OH (OHf) groups free from hydrogen banding. Above T-g another resonance line which can be assigned Co highly mobile OH (OHr) groups in the noncrystalline region appears as a result of the reduction in mole fractions of the OHintra and OHinter groups, in good accord with the confirmation of the rubbery component by the solid-state C-13 NMR line shape analysis. In contrast, the mole fraction of the OHf groups stays constant at -60-160 degreesC, indicating that these OH groups are preferentially distributed in the crystalline region. In order to examine the correlations of the results obtained by H-1 CRAMPS and solid-state C-13 NMR analyses, 2D H-1-C-13 HETCOR spectra have been also measured at room temperature for atacticand main-chain deuterated atactic PVA films. As a result, evident correlations between H-1 OH and C-13 CH constituent lines are observed at a cross polarization (CP) contact time of 120 mus, indicating the validity of the assignments for the H-1 OH and C-13 CH resonance lines made previously as well as in this work.

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Documento generato il 25/11/20 alle ore 00:40:25