Preparation of chitosan-SiO2 nanoparticles by ultrasonic treatment and its effect on the properties of starch film.

The ultrasonic treatment could decrease the particles size of chitosan-SiO2 particles. The EDS of samples with ultrasonic treatment for 0 min and 10 min indicated that the SiO2 was present in prepared chitosan-SiO2 particles. When the ultrasonic time reached 10 min, the chitosan-SiO2 nanoparticles formed and the mean size was 506.7 ± 3.42 nm and the Zeta potential of the chitosan-SiO2 nanoparticles was greater than 30 mV, showing the suspension was a stable dispersed liquid. The chitosan-SiO2 nanoparticles were used as reinforcement in thermoplastic starch films to further verify their performance in enhanced films. The water contact angle of thermoplastic starch film reinforced with chitosan-SiO2 nanoparticles was 44.13 ± 5.02° and had a good mechanical property with tensile strength of 8.91 ± 0.49 MPa. This study indicates that chitosan-SiO2 nanoparticles could be used as a reinforcement to prepare thermoplastic starch films and promote the application of chitosan nanoparticles in nanocomposite films.