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<p>The intriguing properties of cellulosic materials are intimately linked to their molecular structure, which is greatly affected by water. A better understanding of the interaction between cellulose and water can provide crucial insights into improving the performance of natural cellulosic materials. In this study, the state of water and the water-based synergistic relationship among hydroxy (OH) groups, hydrogen bonding, and aggregation state in cellulose isolated from Chinese fir (<i>Cunninghamia lanceolata</i> (Lamb.) Hook.) were systematically investigated across the hygroscopic range. The water states under various relative humidities (RH) conditions were analyzed by 2D time-domain nuclear magnetic resonance (2D TD-NMR); while water-dependent hydroxy accessibility was assessed through deuterium exchange in combination with attenuated total reflectance Fourier-transform infrared spectroscopy (ATR-FTIR), spectra data were further deconvoluted to elucidate the effects of RH on intra- and intermolecular hydrogen bonds, and water-induced changes in the aggregation state were analyzed by ATR-FTIR and X-ray diffraction (XRD). Results demonstrated that increasing RH led to higher moisture content (MC) and greater water mobility in cellulose. As RH increased, hydrogen bonds within the cellulose were disrupted and replaced by water-OH bonds, exposing new sorption sites. Beyond 60% RH, the amount of accessible sorption sites plateaued and incoming water preferentially formed clusters. This disruption of hydrogen bonds within the cellulose, accompanied by enhanced water mobility, facilitated the rearrangement of amorphous cellulose into a more ordered alignment. Furthermore, water-induced changes were also observed in the crystalline structure, where water adsorption indirectly caused a lateral contraction of the cellulose crystals.</p>

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Water variation and its induced structural changes in cellulose extracted from wood

  • 期刊论文

  • 发表日期：

    2025年5月10日

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  • Jiajia Xu,
  • Jingyu Li,
  • Chenqi Wan,
  • Erni Ma

摘要

The intriguing properties of cellulosic materials are intimately linked to their molecular structure, which is greatly affected by water. A better understanding of the interaction between cellulose and water can provide crucial insights into improving the performance of natural cellulosic materials. In this study, the state of water and the water-based synergistic relationship among hydroxy (OH) groups, hydrogen bonding, and aggregation state in cellulose isolated from Chinese fir (Cunninghamia lanceolata (Lamb.) Hook.) were systematically investigated across the hygroscopic range. The water states under various relative humidities (RH) conditions were analyzed by 2D time-domain nuclear magnetic resonance (2D TD-NMR); while water-dependent hydroxy accessibility was assessed through deuterium exchange in combination with attenuated total reflectance Fourier-transform infrared spectroscopy (ATR-FTIR), spectra data were further deconvoluted to elucidate the effects of RH on intra- and intermolecular hydrogen bonds, and water-induced changes in the aggregation state were analyzed by ATR-FTIR and X-ray diffraction (XRD). Results demonstrated that increasing RH led to higher moisture content (MC) and greater water mobility in cellulose. As RH increased, hydrogen bonds within the cellulose were disrupted and replaced by water-OH bonds, exposing new sorption sites. Beyond 60% RH, the amount of accessible sorption sites plateaued and incoming water preferentially formed clusters. This disruption of hydrogen bonds within the cellulose, accompanied by enhanced water mobility, facilitated the rearrangement of amorphous cellulose into a more ordered alignment. Furthermore, water-induced changes were also observed in the crystalline structure, where water adsorption indirectly caused a lateral contraction of the cellulose crystals.