Synthesis and characterization of PEG/(PLA-TiO₂) nanocomposites: effect of TiO₂ nanoparticles on physicochemical, rheological and antibacterial properties

As weak properties of polymer blends may be attributed to phase separation and low compatibility of a dispersed polylactic acid (PLA) phase in the polyethylene glycol (PEG) matrix, this study reports on the role of TiO₂ nanoparticles (NPs) on property enhancement of PEG/(PLA-TiO₂) nanocomposites. After the synthesis of rutile TiO₂ NPs (40 to 80 nm), the nanocomposites were prepared by solution casting of PEG and (PLA-TiO₂) having a ratio PEG/PLA = 70/30 and 0, 1, 3, and 5 wt.-% TiO₂ NPs. The TiO₂ NPs improve phase dispersion and interfacial adhesion in parallel with an increase in crystallinity, degradation temperature and melting temperature towards maximum values at a concentration of 3 wt.-% TiO₂. The ultraviolet absorption was enhanced, and the optical bandgap energy progressively reduced from 4.21 eV to 2.82 eV at 5 wt.-% TiO₂. Rheological tests showed a sixfold increase in storage modulus, indicating strong elastic behaviour in parallel with a stable solid-like region between 10 and 60 °C and a gel-like transition between 70 and 80 °C. Antibacterial tests showed the highest activity at 1 wt.-% TiO₂ against E. coli and S. aureus. Findings confirm that the PEG/PLA nanocomposites with TiO₂ NPs maintain enhanced thermal stability, ultraviolet shielding, antibacterial activity and mechanical strength, being promising for biomedical, environmental, or packaging applications.