Development and characterization of electrospun chitosan-chitin-PVA nanofiber: exploring structural integrity, crystallinity, and thermal stability for advanced applications

Chitosan (CS), a linear polysaccharide derived from chitin (Ch), is known for its excellent biocompatibility, biodegradability, and high chemical resistance, making it suitable for environmental and biomedical applications. However, its relatively low mechanical strength limits its performance in demanding applications. To address this limitation, this study explores the reinforcement of chitosan with chitin via electrospinning, a technique that effectively incorporates chitin as a reinforcing agent. Specifically, electrospun nanofibers were composed of hydrolyzed chitosan (hCS), hydrolyzed chitin (hCh), and polyvinyl alcohol (PVA) as carrier polymer. To evaluate their structural and thermal performance, the nanofibers were characterized using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). SEM images revealed uniform and interconnected fibers, with diameters ranging from 231 to 317 nm, exhibiting a strong correlation between fiber diameter and chitin concentration. FTIR analysis indicated increased hydroxyl and amine group availability in hCS, further enhancing hydrogen bonding, which led to a crystallinity increase from 37.87% to 39.08% after chitosan hydrolysis, as revealed by XRD. Hydrolyzed chitin exhibited a higher crystallinity index of 64.52%. XRD studies showed that increasing hCh content in nanofibers improved crystallinity, with the highest crystallinity index of 51.21% observed in the sample containing 80% hCh. TGA demonstrated that nanofibers with higher chitin content exhibited superior thermal stability, with decomposition temperatures increasing from 317 °C (0% hCh) to 345 °C (100% hCh). This enhancement is attributed to the highly ordered crystalline structure and strong intermolecular hydrogen bonding of hCh. The findings underscore that the integration of chitin into chitosan-based nanofibers significantly improves their structural integrity, thermal resistance, and crystallinity. These optimized nanofibers hold promise for advanced applications in environmental remediation, biomedicine, and sustainable material development.