Enhancement of thermal stability and UV resistance of halloysite nanotubes using zinc oxide functionalization via a solvent-free approach

The aim of this study was to synthesize and evaluate the thermal properties and ultraviolet (UV) resistance of zinc oxide-functionalized halloysite nanotubes (HNT-ZnO). The HNT-ZnO was synthesized using a facile solvent-free route. The properties of the HNT-ZnO nanofillers were characterized using zeta-potential measurement, X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA). The immobilization of ZnO nanoparticles onto HNT is feasible even at the lowest mass ratio of HNT/ZnO. The TGA results indicate that the thermal stability of the HNT-ZnO nanofillers is higher than that of the HNT. Furthermore, UV-Vis diffuse reflectance spectroscopy (UV-DRS) results show that the HNT-ZnO achieve a total reflectance as high as approximately 87.5% in the UV region, as compare with 66.9% for the HNT. In summary, the immobilization of ZnO onto HNT is a viable approach for increasing the thermal stability and improving the UV shielding of HNT.