Fig. 3: Schematic representation of how diffracted neutron intensities from CDH-cellulose II were calculated based on the model of Kolpak and Blackwell.

We represent the case when conversion to cellulose II occurs only when chains move between neighboring cellulose I nanocrystals with opposite polarity. Individual nanocrystals in cellulose I, or crystalline domains in cellulose II, are outlined by broken black lines. Within crystalline domains, hydrogenous and deuterated cellulose chains are represented in blue and red, respectively. The chain direction is represented by an arrow. The top half of the diagram represents the four different possible interactions between hydrogenous and deuterated nanocrystals with opposite polarity. There are equal (50:50) amounts of hydrogenous and deuterated nanocrystals randomly distributed within cellulose I samples and with random up or down orientations with respect to the fiber axis. After mercerization, 50% of crystalline domains will contain equal amounts of hydrogenous and deuterated chains, 25% will contain just hydrogenous chains, and 25% will contain just deuterated chains. KB-calculated-neighbor is obtained from the sum of these contributions. The size of the unit cells for 25% CH and 25% CD and the averaged cell for 50% CDH is the same. Therefore, the position of intensities in the diffraction pattern from a sample containing mixtures of these different unit cells would coincide. We do not expect additional reflections.