R. Panackal Shibu, S.L. Sagala, B. Kelly, J.L. Shamshina
Texas Tech University,
United States
Keywords: biobased nanomaterials
Summary:
The field of nanocrystals has broadened its reach across numerous scientific and technological domains, catalyzing innovations that increasingly prioritize biobased nanomaterials over conventional synthetic ones. Consequently, bionanomaterials have attracted growing attention in diverse sectors ranging from materials engineering to biomedical applications. Among these, chitin nanocrystals stand out due to their abundance in nature, biodegradability, biocompatibility, and exceptional mechanical properties. They are primarily derived from crustacean shells, insect cuticles, and fungal cell walls. Despite the vast global accumulation of crustacean shell waste, only a small portion is currently utilized, leaving a substantial underexploited resource, rich in chitin, which constitutes approximately 25–30% of the shell biomass. Traditional methods for isolating chitin nanowhiskers (ChNWs) generally involve harsh acid and alkali treatments, leading to considerable environmental challenges. To overcome these issues, we developed and optimized ionic liquid (IL)-based approaches for the direct extraction of ChNWs from a wide range of biomass sources, including shrimp and crab shells, squid pens, black soldier fly larvae, white mushrooms, and practical-grade chitin. The objective was to examine how both biomass origin and IL type influence essential structural and physicochemical parameters, namely purity, aspect ratio, surface chemistry, molecular weight (MW), degree of acetylation (%DA), and crystallinity index (%CrI). Although ILs such as [C4mim][HSO4] were effective in producing nanowhiskers of desirable quality, their high cost and limited scalability restricted industrial application. To address this, our subsequent investigations focused on identifying cost-efficient ILs capable of achieving comparable results. In this context, we evaluated [HN222][HSO4] and [Hmim][HSO4] against benchmark ILs, comparing their performance in terms of nanowhisker yield, morphology, crystallinity, degree of acetylation, thermal stability, and molecular weight. These alternative ILs demonstrated equivalent outcomes, confirming their potential for environmentally sustainable and economically feasible large-scale chitin processing. Building upon these advancements, we extended our work to explore the application of ChNWs as reinforcing agents in polyamide 6 (PA6) nanocomposite films, utilizing nanowhiskers derived from both purified chitin and raw shrimp shell biomass. The composites displayed a percolated nanofiber network at optimized filler concentrations, resulting in significant improvements in mechanical strength, thermal stability, and processability. Our ongoing research phase focuses on the scale-up (10 L reactor) and process optimization of ChNW isolation. This stage integrates the insights gained from laboratory studies to evaluate biomass loading, IL utilization efficiency, and the energy and environmental implications of larger-scale operations. The overarching goal is to establish a pilot-scale, industrially viable process that is both cost-effective and environmentally benign, offering a practical and scalable alternative to traditional acid hydrolysis and other expensive “green” extraction methodologies.