Fig. 3(c) shows the morphology of chitosan NPs and chitosan NFs mixture. It could clearly be seen that both nanofiber and nanoparticle phases are present in the mixture. Close analysis revealed that large bundles seen in the TEM images are due to the blend of smaller nanofibers. Chitosan NPs were adhered to chitosan NFs, resulting an aggregated structure.
TEM image of chitosan NFs is shown in Fig. 4(d). Majority of the fibers have diameters less than 100 nm and lengths less than 3 μm. It is possible that during the process of deacetylation alkali has penetrated the chitin NFs structure resulting a swollen fiber. We could also observe small nanofiber aggregates to make larger nanofiber bundles. When compared with chitin NFs, chitosan NFs appears to be less defined in the TEM images indicating the amorphous structure of these nanofibers. Also, nanofiber bundles were made out of much shorter nanofibers than in the case of chitin NFs. This is possibly due to the lengthwise scissoring of these small nanofibers due to cavitation in the preparation process.