Moisture uptake in native cellulose – the roles of different hydrogen bonds: a dynamic FT-IR study using Deuterium exchange

Author： Hofstetter Karin Hinterstoisser Barbara Salmén Lennart

Publisher： Springer Publishing Company

ISSN： 0969-0239

Source： Cellulose, Vol.13, Iss.2, 2006-04, pp. : 131-145

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Abstract

This paper aims at a better understanding of the interaction between cellulose and moisture. In particular, the role of different hydrogen bonds in moisture uptake is investigated. Dynamic Fourier transform infrared spectroscopy (FT-IR) has been used in combination with deuterium exchange, which permits the labelling of cellulose domains with different accessibilities.The static spectra indicate a marked exchange of deuterium for the O2–H…O6 bonds, but only a limited exchange for the O3–H…O5 bonds. In the dynamic FT-IR spectra, deuteration gives rise to the growth of a broad band at wavenumbers around 2500 cm⁻¹. The rather unstructured appearance of the band suggests that deuteration is occurring only on the surface of the cellulose crystallites, i.e. in more or less non-load-carrying parts. This is corroborated by the lack of split peaks related to OD bonds in this band. In agreement with these observations, the split peak related to O3–H…O5 bonds and assigned to the load carrying cellulose structure increases during both H₂O and D₂O moisture conditioning, indicating a shift of the load transfer towards the backbone of the cellulose structure.