Relative susceptibility of the Iα and Iβ phases of cellulose towards acetylation

The relative reactivity of the Iα and Iβ phases of Valonia cellulose toward partial homogeneous acetylation was investigated by FT-IR and CP/MAS 13C-NMR spectroscopy. At the beginning of the acetylation and when only partial reaction was achieved, it was found that the reactivity of the Iα phase was...

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Bibliographic Details
Published in:Cellulose (London) 2000-06, Vol.7 (2), p.119-132
Main Authors: Sassi, Jean-François, Tekely, Piotr, Chanzy, Henri
Format: Article
Language:English
Subjects:
Accessibility
Acetylation
Cellulose
Domains
Infrared spectroscopy
NMR spectroscopy
Phases
Reactivity
Thickness
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Summary:The relative reactivity of the Iα and Iβ phases of Valonia cellulose toward partial homogeneous acetylation was investigated by FT-IR and CP/MAS 13C-NMR spectroscopy. At the beginning of the acetylation and when only partial reaction was achieved, it was found that the reactivity of the Iα phase was substantially higher than that of the corresponding Iβ component. At a later stage of acetylation, the difference in reactivity between the two phases was less pronounced. In correlation with previous ultrastructural observations (Sassi and Chanzy, 1995), it can be concluded that at equivalent accessibility, the Iα phase of cellulose is indeed more reactive toward acetylation than the Iβ phase. The homogeneous acetylation of cellulose is essentially a surface reaction that affects only the accessible parts located at the surface of the microfibrils. The decrease in the rate of Iα phase disappearance with acetylation time confirms therefore that the microstructure of Valonia is made of domains that are distributed throughout the thickness of its microfibrils.
ISSN:0969-0239
1572-882X
DOI:10.1023/A:1009224008802