Impact of enzymatic hydrolysis and drying on cellulose nanocrystal properties

Cellulose nanocrystals (CNCs) are highly crystalline, rod-like nanoparticles derived from cellulose, with significant potential for various applications. Their properties-size, crystallinity, thermal stability, and surface chemistry-depend on production methods and processing conditions. While CNCs are typically used as aqueous colloidal dispersions or gel-like forms, certain applications, such as reinforcement for polymer nanocomposites, require CNCs in a dried powder form. However, drying often induces agglomeration, negatively impacting CNC performance. In this study, CNCs were successfully produced via enzymatic hydrolysis using a commercial cellulase blend. Particle size, chemical composition, and X-ray diffraction (XRD) analyses identified optimal production conditions: 5 U/g enzyme loading and 72 h hydrolysis, achieving a maximum yield of 75.7 % even at larger scale. Atomic force microscopy (AFM) confirmed the individual nanoparticle morphology, while XRD and thermogravimetric analysis (TGA) demonstrated preserved crystallinity and thermal stability. The CNCs obtained under these optimized conditions were then subjected to various drying methods. Spray drying (CNC-SD) proved the most effective, yielding uniform, thermally stable particles with higher crystallinity and reduced agglomeration compared to freeze-dried (CNC-FD) and oven-dried (CNC-OD) samples. CNC-SD also exhibited lower moisture loss, enhancing its suitability for nanocomposites. These findings demonstrate the importance of optimizing CNC production and drying techniques to obtain high-performance CNCs. Combining enzymatic hydrolysis and efficient drying strategies provides a robust framework for integrating CNCs into advanced composite materials and expanding their industrial applications in sustainable technologies.