*3.4. Morphology*

The morphology of nanocrystals after the hydrolysis treatment was characterized by TEM and STEM observations. Figure 4 presents a comparison of TEM and STEM micrograph of sample BC-NC obtained from a 30 min microwave reaction with MnCl2 catalyst (5% *w*/*w*) at 125 ◦C to commercial NCC. Both samples were prepared in the same conditions, and as shown, are similarly constituted of a mixture of fibrillated structure with variable length and smaller needles or nano-rods. It seems that the fibrillated structures are in fact constituted of the densely-packed needles. The BC-NC nano-rods are of (164.51 ± 7.56) nm in length with an average diameter of (25.05 ± 2.80) nm. They look like the commercial forms which are (90.94 ± 10.05) nm in length with an average diameter of (12.58 ± 0.87) nm. This result confirmed the crystalline structure already described with a very close similarity to commercially-available nanocrystalline cellulose.

**Figure 4.** Transmission Electron Microscopy (TEM) and Scanning Transmission Electron Microscopy (STEM) micrograph of BC-NC (**A**,**C**) produced with 0.1M HCl and 5% *w*/*w* of MnCl2 compare to commercial NCC (**B**,**D**).
