R. Panackal Shibu, S.L. Sagala, B. Kelly, J.L. Shamshina
Texas Tech University,
United States
Keywords: biobased nanomaterials
Summary:
The realm of nanocrystals has expanded its influence across numerous scientific disciplines, driving innovations that increasingly favor biobased nanomaterials over conventional counterparts. As a result, the demand for bionanomaterials has surged across diverse fields, from material engineering to biomedical science. Among those, chitin nanocrystals have garnered extensive scientific focus due to their natural abundance, biodegradability, biocompatibility, and impressive mechanical strength. These nanocrystals are predominantly sourced from crustacean shells, insect exoskeletons, and fungal cell walls. Despite the massive generation of crustacean shell waste globally, only a fraction is currently valorized, leaving a significant untapped resource rich in chitin, comprising approximately 25–30% of crustacean shell biomass. The traditional approaches for isolating chitin nanowhiskers (ChNWs) typically rely on harsh chemical treatments involving strong acids and alkalis, which generate significant environmental concerns. To address these limitations, we have extensively explored ionic liquid (IL)-based strategies for the direct extraction of ChNWs from diverse biomass sources such as shrimp and crab shells, squid pens, black soldier fly larvae, white mushrooms, and practical-grade chitin. The primary aim was to evaluate how both the nature of the biomass and the type of IL employed affect key material attributes, including purity, aspect ratio, surface chemistry, molecular weight (MW), degree of acetylation (%DA), and crystallinity index (%CrI) . Although ILs such as [C4mim][HSO4] efficiently produce high-quality nanomaterials, their cost and limited scalability restrict industrial use. Our subsequent research focused on identifying cost-effective ILs that deliver comparable performance. Following this, we evaluated lower-cost ILs, [HN222][HSO4] and [Hmim][ HSO4], comparing nanowhisker yield, morphology, crystallinity, degree of acetylation, thermal stability, and molecular weight . These ILs achieved comparable performance, demonstrating their potential for environmentally sustainable and economically viable large-scale chitin processing. Building on these findings, we applied the resulting ChNWs in polyamide 6 (PA6) nanocomposite films, incorporating nanowhiskers obtained directly from both purified chitin and raw shrimp shell biomass. The resulting materials exhibited a percolated nanofiber network at optimized filler loadings, leading to marked improvements in mechanical strength, thermal stability, and processability. Our current phase of research centers on the scale-up (10 L) and process optimization of ChNW isolation. This work leverages promising laboratory-scale results to assess biomass loading capacity, IL consumption, and the energy and environmental impacts associated with larger-scale operations. The ultimate goal is to establish a pilot-scale, industrially viable process that is both economically and environmentally sustainable, providing a practical alternative to conventional acid hydrolysis and other costly “green” extraction routes.