Study of interfaces in polymer-metal oxide films and free-volume hole using low-energy positron lifetime measurements

摘要

To reveal how the distribution of different nano fillers affect the UV-shielding efficiency of their polymer-based composites and to further develop a simple strategy to refrain the erection of the composites, we prepared ZnO doped polystyrene (PS/ZnO) and TiO2doped polystyrene (PS/TiO2) films by the solution cast technique with different concentrations of ZnO and TiO2(0.25%, 0.5%, 0.75% and 1%.). Contrary to the common observation, the better tunability for UV shielding efficiency was found in the case of TiO2as compared to ZnO. This is mainly due to the appearance of a rod like structure on neat PS which has improved the dispersion as well as provides a higher interface area that enhanced the UV-absorption efficiency of the PS matrix. This analysis is equally supported by the PALS study where the free volume was closely associated with the interfacial interaction between the filler and the PS matrix. These observations recommend that the better dispersion of filler particles leads a stronger interfacial interaction and enhances the UV-protection efficiency of the composite materials.