Cellulose samples are routinely analyzed by X-ray diffraction to determine their crystal type (polymorph) and crystallinity. However, the connection is seldom made between those efforts and the crystal structures of cellulose that have been proposed with synchrotron X-radiation and neutron diffraction over the past decade or so. In part, this desirable connection is thwarted by the use of different conventions for description of the unit cells of the crystal structures. In the present work, powder diffraction patterns from cellulose Iα, Iβ, II, IIII, and IIIII were calculated based on the published atomic coordinates and unit cell dimensions contained in modified “crystal information files” (.cif) that are supplied in the Supplementary Information. The calculations used peak widths at half maximum height of both 0.1 and 1.5° 2θ, providing both highly resolved indications of the contributions of each contributing reflection to the observable diffraction peaks as well as intensity profiles that more closely resemble those from practical cellulose samples. Miller indices are shown for each contributing peak that conform to the convention with c as the fiber axis, a right-handed relationship among the axes and the length of a < b. Adoption of this convention, already used for crystal structure determinations, is also urged for routine studies of polymorph and crystallinity. The calculated patterns are shown with and without preferred orientation along the fiber axis. Diffraction intensities, output by the Mercury program from the Cambridge Crystallographic Data Centre, have several uses including comparisons with experimental data. Calculated intensities from different polymorphs can be added in varying proportions using a spreadsheet program to simulate patterns such as those from partially mercerized cellulose or various composites.
Cellulose crystal structure Miller indices Powder diffraction patterns Convention
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Paul Langan kindly provided the .cif file for cellulose II. The research was partly inspired by collaborative efforts with Cotton, Incorporated. Drs. Santiago Cintrón, Seong Kim and Xueming Zhang kindly commented on preliminary versions of the manuscript. Dr. Edwin Stevens consulted on the effects of preferred orientation on the cellulose Iα pattern.
French AD, Roughead WA, Miller DP (1987) X-ray diffraction studies of ramie cellulose I. In: Atalla RH (ed) The structures of cellulose—characterization of the solid states. ACS Symp Ser 340, pp 15–17Google Scholar
Macrae CF, Gruno IJ, Chisholm JA, Edgington PR, McCabe P, Pidcock E, Rodriguez-Monge L, Taylor R, van de Streek J, Wood PA (2008) Mercury CSD 2.0-new features for the visualization and investigation of crystal structures. J Appl Crystallogr 41:466–470. doi:10.1107/S0021889807067908CrossRefGoogle Scholar
Nishiyama Y, Langan P, Chanzy H (2002) Crystal structure and hydrogen-bonding system in cellulose Iβ from synchrotron X-ray and neutron fiber diffraction. J Am Chem Soc 124(31):9074–9082. doi:10.1021/ja0257319CrossRefGoogle Scholar
Nishiyama Y, Sugiyama J, Chanzy H, Langan P (2003) Crystal structure and hydrogen bonding system in cellulose Iα, from synchrotron X-ray and neutron fiber diffraction. J Am Chem Soc 125:14300–14306. doi:10.1021/ja037055wCrossRefGoogle Scholar
Sarko A, Muggli R (1974) Packing analysis of carbohydrates and polysaccharides III. Valonia cellulose and cellulose II. Macromolecules 7:486–494CrossRefGoogle Scholar
Segal L, Creely JJ, Martin AE, Conrad CM (1959) An empirical method for estimating the degree of crystallinity of native cellulose using the X-ray diffractometer. Text Res J 29(10):786–794. doi:10.1177/004051755902901003CrossRefGoogle Scholar
Wada M, Chanzy H, Nishiyama Y, Langan P (2004) Cellulose IIII crystal structure and hydrogen bonding by synchrotron X-ray and neutron fiber diffraction. Macromolecules 37:8548–8555. doi:10.1021/ma0485585CrossRefGoogle Scholar
Wada M, Heux L, Nishiyama Y, Langan P (2009) X-ray crystallographic, scanning microprobe X-ray diffraction, and cross-polarized/magic angle spinning 13C NMR studies of the structure of cellulose IIIII. Biomacromolecules 10:302–309. doi:10.1021/bm8010227CrossRefGoogle Scholar
Woodcock C, Sarko A (1980) Packing analysis of carbohydrates and polysaccharides 11. Molecular and crystal structure of native ramie cellulose. Macromolecules 13:1183–1187. doi:10.1021/ma60077a030CrossRefGoogle Scholar