Semiquantitative Structural Analysis of Highly Anisotropic Cellulose Nanocolloids.

We report a method for the semiquantitative structural analysis of highly anisotropic nanocolloids by means of their "coffee rings", which were readily formed via the evaporation of droplets of the cellulose nanocolloidal suspensions. The widths of the coffee rings reflected the effective aspect ratios and the conformation of the colloids in water, owing to the excluded volume effect. The theory developed here succeeded in estimating the relative length of the cellulose nanofibrils, which were obtained from Japanese cedar pulp using a grinder, as 11.33 μm. The coffee rings allow the comprehensive structures of colloids to be semiquantitatively revealed and also allow the length or size of colloids in different systems to be compared.