Our studies of cellulose structure based on X-ray diffractometry, Raman spectroscopy, and Solid State ¹³C-NMR have led us to a model which addresses questions of structure at two levels. The first is that of the organization of individual chains. Two stable ordered states of cellulose chains are postulated, together with a disordered state in which there is less coherence between the orientations of adjacent anhydroglucose rings. The ordered states are identified as kᵢ and kᵢᵢ based on their predominance in celluloses I and II, respectively; both conformations are based on the dimeric anhydrocellobiose as the basic repeat until in the ordered chain. The disordered state is identified as kₒ.
The second level of organization is that of aggregation of chains into three-dimensionally ordered crystalline domains. At this level our model recognizes two crystalline forms within the native state. These are identified as Iα and Iß, the first found to be dominant in bacterial and algal celluloses, the second dominant in celluloses from higher plants. These two forms are found to contain chains possessing the same molecular conformation ᵏI, but the patterns of hydrogen bonding are found to be different. Cellulose II, which is derived from the native state by mercerization or regeneration at low temperatures, is found to consist predominantly of chains in the ᵏII conformation in yet a third distinct crystalline lattice.