Abstract
A protocol was developed to freeze-trap (at 150 K) cellulose as it is undergoing liquid ammonia pretreatment, and then to collect X-ray diffraction data from the freeze-trapped reactants as the reaction is allowed to proceed and ammonia is allowed to melt and then evaporate, leaving ammonia-cellulose I. Cellulose adopts a new two-chain crystal form, which we call low temperature phase ammonia-cellulose I (two-chains and ~ten ammonia molecules within a unit cell of a = 15.49 Å, b = 11.35 Å, c = 10.42 Å and γ = 143.5°). A schematic model was developed that is characterized by sheets of hydrophobically stacked cellulose-chains with hydrophilic channels between them that are filled with ammonia molecules. Neighboring chains in these sheets have either different conformations or are staggered with respect to each other. As ammonia is allowed to evaporate, the unit cell size is reduced by a factor of two as the two independent chains become identical.
Original language | English |
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Pages (from-to) | 1117-1126 |
Number of pages | 10 |
Journal | Cellulose |
Volume | 21 |
Issue number | 3 |
DOIs | |
State | Published - Jun 2014 |
Funding
Acknowledgments This work was funded by the Genomic Science Program of the Office of Biological and Environmental Research, US Department of Energy, under FWP ERKP752.
Keywords
- AFEX
- Amine complex
- Biomass
- Low temperature phase (LTP) ammonia-cellulose I
- X-ray diffraction