Chitosan/ZnO nanohybrid as an efficacious compatibilizer for PLA/PBS blend suitable candidate for biodegradable...

In this study, chitosan-zinc oxide (CS-ZnO) nanohybrids were investigated as a new compatibilizer for biodegradable poly(lactic acid)/poly(butylene succinate) (PLA/PBS) blends. The novelty of this work lies in the synergistic effect arising from the hybridization of ZnO with chitosan, which enhances the interfacial compatibility between PLA and PBS and overcomes the limitations of pure ZnO, such as agglomeration and weak adhesion to the polymer matrix. PLA/PBS blends (80/20 wt%) were reinforced with different concentrations (0.1-0.5 wt%) of ZnO and CS-ZnO via solution casting. Mechanical testing showed that the addition of only 0.25 wt% of CS-ZnO improved the elongation at break by 50% and the tensile strength by 52% compared to pure ZnO. Morphological analysis using scanning electron microscopy (SEM) showed that the addition of only 0.25 wt% of CS-ZnO into PLA/PBS decreased the radius of PBS droplets from 423 nm to 349 nm, indicating improved compatibility between the PLA and PBS phases. This compatibility was further supported by rheological measurements, which showed an increased viscosity in the nano-hybrid-filled blend from 50 Pa.s to 110 Pa.s. Hydrolytic degradation tests, evaluated through mass loss over time, revealed accelerated degradation in CS-ZnO nanocomposites, because of increased hydrophilicity and interfacial areas. This study employed Density Functional Theory (DFT) with the semi-empirical PM6 method to estimate binding energies in binary and ternary systems, confirming experimental findings. Strong negative binding energies for PLA-ZnO and PBS-ZnO suggest high interfacial affinity, while PLA-CS showed weakly unfavorable interactions. The addition of ZnO to PLA-CS and PBS-CS systems resulted in favorable binding energies, emphasizing CS-ZnO hybrids' role in improving compatibility, stability, and bioactivity-controlled degradability of PLA/PBS-based nanocomposites, advancing sustainable materials for packaging and biomedical applications.