Innovative controllable photocatalytic degradation of polystyrene with hindered amine modified aromatic polyamide dendrimer/ polystyrene-grafted-TiO2 photocatalyst under solar light irradiation

A novel hindered amine modified aromatic polyamide dendrimer/polystyrene-grafted-TiO2 hybrid photocatalyst (HADPG-TiO2) was synthesized. And a new kind of controllable photodegradable polystyrene (PS) composite was prepared by embedding the HADPG-TiO2 into the commercial polystyrene. Solid-phase photocatalytic degradation of the PS-HADPG-TiO2 composite was carried out in ambient air at room temperature under solar light irradiation. The HADPG-TiO2 was characterized by FT-IR and scanning electron microscopy (SEM), X-ray diffraction (XRD) and UV-vis diffuse reflectance spectroscopy, in comparison with reference materials (plain TiO2). The properties of PS-HADPG-TiO2 films were compared with those of the pure PS films and PS-TiO2 films by methods such as weight loss measurement, SEM and tensile properties measurement. The results showed that the HADPG-TiO2 had a better dispersion in PS polymer and could absorb the visible light. The PS-HADPG-TiO2 films had better tensile properties, compared with the pure PS films and PS-TiO2 films. Moreover, the as-prepared PS-HADPG-TiO2 films showed more excellent photostability under solar light irradiation for 0-250 h and higher photodegradable efficiency under the solar light irradiation for 600 h than the pure PS films and PS-TiO2 films. The photocatalytic degradation mechanism of the films was briefly discussed. The novel fabrication method of composite polymer provides a valuable way for developing highly efficient and controllable photodegradable plastics.