scholarly journals CONFORMATION OF CHITIN ANDN-ACYL CHITOSANS IN SOLID STATE AS REVEALED BY13C CROSS POLARIZATION/MAGIC ANGLE SPINNING (CP/MAS) NMR SPECTROSCOPY

1981 ◽  
Vol 10 (10) ◽  
pp. 1479-1482 ◽  
Author(s):  
Hazime Saitô ◽  
Ryoko Tabeta ◽  
Shigehiro Hirano
Keyword(s):  
Solid State ◽  
Nmr Spectroscopy ◽  
Magic Angle Spinning ◽  
Mas Nmr ◽  
Magic Angle ◽  
Cross Polarization ◽  
Angle Spinning ◽  
Cp Mas Nmr

Band-Selective1H−13C Cross-Polarization in Fast Magic Angle Spinning Solid-State NMR Spectroscopy

2008 ◽  
Vol 130 (51) ◽  
pp. 17216-17217 ◽  
Author(s):  
Ségolène Laage ◽  
Alessandro Marchetti ◽  
Julien Sein ◽  
Roberta Pierattelli ◽  
Hans Juergen Sass ◽  
...  
Keyword(s):  
Solid State ◽  
Nmr Spectroscopy ◽  
Solid State Nmr ◽  
Magic Angle Spinning ◽  
Magic Angle ◽  
Cross Polarization ◽  
Solid State Nmr Spectroscopy ◽  
Angle Spinning ◽  
Fast Magic Angle Spinning

Chemical reaction of alkoxysilane molecules in wood modified with silanol groups

Holzforschung ◽  
2006 ◽  
Vol 60 (3) ◽  
pp. 271-277 ◽  
Author(s):  
Philippe Tingaut ◽  
Oliver Weigenand ◽  
Carsten Mai ◽  
Holger Militz ◽  
Gilles Sèbe
Keyword(s):  
Nmr Spectroscopy ◽  
Chemical Reaction ◽  
Magic Angle Spinning ◽  
Mas Nmr ◽  
Dibutyltin Dilaurate ◽  
Magic Angle ◽  
Pre Treatment ◽  
Angle Spinning ◽  
Cp Mas Nmr ◽  
Modified Wood

Abstract Chemical reaction between silanol-modified wood and methyltrimethoxysilane (MTMS) was carried out using two different approaches with dibutyltin dilaurate (DBTDL) or ethylamine (EtNH2) as catalysts. Modifications were characterised by Fourier-transform infrared (FTIR) spectroscopy, as well as solid-state 13C and 29Si cross-polarisation with magic-angle spinning nuclear magnetic resonance (CP-MAS NMR) spectroscopy and scanning electron microscopy-energy dispersive X-ray (SEM-EDX) analysis. Silanol-modified wood was obtained by carbamoylation reaction with 3-isocyanatopropyltriethoxysilane (IPTES) and subsequent hydrolysis of the triethoxysilane end groups. 29Si CP-MAS NMR spectroscopy indicated that SiOH groups existed mostly in the form of mono- and di-condensed structures in wood, whatever the level of modification (low or high). The attachment of methyltrimethoxysilane (MTMS) molecules to silanol sites was apparently achieved when ethylamine was used as a catalyst. The reacted MTMS remaining in wood was found to exist mostly in the form of polysiloxane polymers (or oligomers), as shown by 29Si CP-MAS NMR results. Reactions performed with unmodified wood were much less effective, thereby demonstrating the importance of the IPTES pre-treatment.

From Precursors to Non-Oxide Ceramics: Pyrolytic Mechanisms Studied by NMR

1995 ◽  
Vol 410 ◽  
Author(s):  
W. M. Sigmund ◽  
M. Feike ◽  
H. W. Spiess ◽  
F. Aldinger
Keyword(s):  
Magic Angle Spinning ◽  
Mas Nmr ◽  
Inert Gas ◽  
Magic Angle ◽  
Oxide Ceramics ◽  
Cross Polarization ◽  
Chemical Structures ◽  
Angle Spinning ◽  
Cp Mas Nmr ◽  
Probe Head

ABSTRACTThe pyrolysis of a poly ethylsilazane was studied using a CO2-laser beam heated solid state MAS-NMR probe head. Chemical structures of the intermediate stages could be identified. The analogy of the pyrolysis evolution for the following two different methods could be shown: A) in an inert gas furnace conventionally prepared and B) laser irradiated in the NMR probe head under magic-angle spinning (MAS) conditions. Samples prepared by method A were studied by 29Si MAS-NMR and samples prepared by method B were studied with an appropriate cross polarization time by 29Si CP-MAS-NMR. Both experiments showed the same mechanisms for the pyrolysis as the polymer is transformed into a Si3N4/C ceramic.

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