Abstract: Nano-titanium dioxide (TiO2) solution was prepared from titanium tetraisopropoxide (TTIP) using the solgel method. The molar ratio between TTIP and water was optimized for smaller particle size. The nano-titanium dioxide was amorphous nanoparticles with high visible light utilization as characterized by Fourier transform infrared (FTIR) spectroscopy, UV spectroscopy, X-ray diffraction and particle size analysis. Furthermore polylactic acid/titanium dioxide (PLA/nano-TiO2) composite film was prepared by solution blending method, and the properties of composite films with different titanium dioxide contents were studied. The PLA/0.6% nano-TiO2 composite film had the maximum tensile strength of 63.3 MPa and the minimum elongation at break of 2.3%. The water resistance test indicated that the contact angle of the PLA/nano-composite film was lower than that of pure PLA film (72.83° versus 78.40°). In addition, the water absorption rate of was significantly higher than that of pure PLA film (1.48% versus 0.56%) and there was also an increase in water vapor permeability as compared to pure PLA film (4.66 × 10-8 (g·m)/(m2·h·Pa) versus 3.46 × 10-8 (g·m)/(m2·h·Pa)). Meanwhile, the composite film had a significant antibacterial effect under ultraviolet light.

Key words: amorphous nanotitanium dioxide, polylactic acid, composite film, mechanical properties, antibacterial activity