Urchin-like WO₃ Particles Form Honeycomb-like Structured PLA/WO₃ Nanocomposites with Enhanced Crystallinity, Thermal Stability, Rheological, and UV-Blocking and Antifungal Activity

The development of poly(lactic acid) (PLA) nanocomposites incorporating urchin-like WO₃ particles through a cost-effective solution-casting method has led to significant enhancements in structural, thermal, optical, and rheological properties. The incorporation of these WO₃ particles up to 7 wt% resulted in the formation of an irregular honeycomb-like morphology with broad pore sizes ranging from 14.1 to 24.7 µm, as confirmed by SEM and EDX analysis. The urchin-like WO₃ particles acted as effective nucleating agents, increasing the crystallinity of PLA from 40% to 50% and achieving an impressive overall crystallinity rate of 97%. Differential scanning calorimetry (DSC) revealed an 11 K reduction in the crystalline phase transition temperature while maintaining stable melting (Tm) and glass transition (Tg) temperatures. Thermal analysis indicated a significant decrease in the onset of degradation and maximum thermal stability (T_max), with a reduction of 21 K due to the incorporation of the WO₃ particles. Optical measurements showed enhancement of UV-blocking properties from 9% to 55% with the WO₃ particle loading. Rheological tests demonstrated substantial improvements in viscoelastic properties, including a remarkable 30-fold increase in storage modulus, suggesting enhanced gel formation. Although the nanocomposites showed minimal antibacterial activity against Escherichia coli and Staphylococcus aureus, they exhibited significant antifungal activity against Candida albicans. These results underscore the potential of the PLA/WO₃ nanocomposites for advanced material applications, particularly where enhanced mechanical, thermal, optical, and antifungal performance is required.