Analyzing three‐dimensional structure and geometrical shape of individual cellulose nanocrystal from switchgrass

The three‐dimensional morphology, size distribution, and structure of individual cellulose nanocrystals (CNCs) isolated from switchgrass (Panicumvirgatum L), a representative raw biomass material, were investigated in this research. Width and height evolutions along the individual CNC longitudinal direction were statistically and quantitatively characterized using transmission electron microscopy (TEM) and atomic force microscopy (AFM). Lognormal distribution was identified as the most likely for cellulose nanocrystals’ size distribution. Height and width dimensions were shown to decrease toward the ends from the midpoint of individual CNCs, implying a spindle shape. The observed rough surfaces of CNCs were explainable as the results of acid etching of the subcrystalline and disordered region located at the surface. X‐ray diffraction analysis of crystallite size accompanied with TEM and AFM measurements revealed that the cross‐sectional dimensions of individual switchgrass CNC were either rectangularly or elliptically shaped, with an approximately 3–5 nm lateral element length range. POLYM. COMPOS., 38:2368–2377, 2017. © 2015 Society of Plastics Engineers