Improving the Tensile Properties and Wettability of Aspergillus Mycelium Biomaterial through a Mycelial Pulping Process

Fungal mycelium offers a renewable, biodegradable polymer platform to replace petroleum-based materials in advanced sustainable applications. Its inherent three-dimensional fibrous network provides natural porous architecture, offering broad potential for the development of eco-friendly functional materials. However, untreated mycelium generally have limited mechanical strength and water uptake, motivating chemical modification to improve their structure–property relationships. Here, Mycelium obtained from submerged fermentation was modified via two routes: (i) NaOH deacetylation, converting chitin to chitosan, and (ii) NaOH/H2O2 oxidative pulping to remove matrix polymers and extract aligned fibers. The NaOH treatment produced chitosan-rich networks with free amino groups, enhancing interchain hydrogen bonding and surface polarity; this significantly increased tensile strength, consistent with chitosan’s known mechanical robustness. Oxidative pulping further removed amorphous cell-wall constituents and extruded polymeric material, flattening and bundling the hyphal fibers. These changes were accompanied by a marked rise in crystallinity, akin to lignocellulosic pulping where delignification and fibrillation improve fiber bonding. SEM and XRD analyses confirmed the transition from a porous network to a compact, highly ordered fibrous sheet after pulping. As a result, the pulped webs exhibited superior performance: ultimate tensile strength 15.5 MPa, elongation 4.6%, and swelling capacity 140%, far exceeding the deacetylated and native samples. These metrics indicate a favorable strength–absorption balance, as the high swelling demonstrates effective fluid uptake capacity. Notably, the treatments employ only aqueous NaOH and H2O2, aligning with green chemistry principles. The robust strength, flexibility, and high water uptake of the pulped, chitosan-enriched mycelia thus make them promising sustainable and biodegradable materials for sustainable applications.