Comparison of the properties of nanopaper from chitin nanofibers prepared by mechanical and TEMPO-oxidized methods

This study compares the structural, optical, and mechanical characteristics of chitin nanopapers fabricated through mechanical fibrillation and TEMPO-mediated oxidation. The TEMPO-oxidized nanopaper exhibited higher optical transparency (approximately 92%) than the mechanically fibrillated sample (around 60%), primarily due to enhanced nanofiber dispersion and smaller fibril diameters. In contrast, the mechanically produced nanopaper showed greater crystallinity (above 90%) and stronger hydrogen bonding, resulting in higher tensile strength and Young’s modulus compared with the oxidized counterpart. Microscopic analyses confirmed the more homogeneous and well-dispersed network in TEMPO-treated samples, while spectroscopic results indicated the presence of carboxylate groups introduced by oxidation. The research overall highlights the usability of both nanopaper types in different applications and how TEMPO-oxidized nanopaper fits best under transparent and biodegradable packaging and mechanically treated nanopaper in applications requiring more strength.