X-ray Structure of Mercerized Cellulose II at 1 Å Resolution

A revised crystal structure for mercerized cellulose based on high-resolution synchrotron X-ray data collected from ramie fibers is reported (space group P21, a = 8.10(3) Å, b = 9.03(3) Å, c = 10.31(5) Å, γ = 117.10(5)°; 751 reflections in 304 composite spots; θ < 21.11°; λ = 0.7208 Å; LALS refinement with d > 1.5 Å, R' ' = 0.16; SHELX97 refinement with d > 1 Å, R = 0.21). As with regenerated cellulose the crystal structure consists of antiparallel chains with different conformations but with the hydroxymethyl groups of both chains near the gt position. However, the conformation of the hydroxymethyl group of the center chain in the structure reported here differs significantly from the conformation in regenerated cellulose. This may be related to a large observed difference in the amount of hydroxymethyl group disorder: ∼30% for regenerated cellulose and ∼10% for mercerized cellulose.