CELL 178 |
| Molecular dynamics simulations of cellulose allomorphs have been performed, both as small hydrated crystallites and as "infinite" crystals. The hydrated crystallites were not subject to artificial constraints imposed by a strict unit cell, as is assumed during diffraction based analysis. This freedom allowed the crystallites to relax and display complex behavior that corresponds to experimental observations such as an overall twisted shape, but there were also significant differences in internal structure. To determine the extent to which these results depend on force field parameters, several carbohydrate parameter sets were used to simulate cellulose Iα and Iβ. The influence of microfibril length and diameter on twist magnitude was as expected with wider microfibrils closer to the proposed hydrogen bonded sheet structures. However, one small diameter microfibril (4x4 chains) showed a significant twist of 5 degrees/nm, as opposed to the more usual 0.5 degrees/nm for microfibrils more plant-like in diameter (6x6 chains). |
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Structure and Properties of Cellulosic Polymers, Assemblies, and Nanocomposites
8:00 AM-11:45 AM, Tuesday, April 8, 2008 Morial Convention Center -- Rm. R07, Oral
Division of Cellulose & Renewable Materials |