Optical properties of an organic-inorganic hybrid film made of regenerated cellulose doped with light-scattering TiO2 particles

Abstract

Inorganic-organic composites offer immense potential for developing materials with, e.g. improved chemical, optical and electrical properties, by combining characteristics from both substances. In this study, sustainable and modifiable regenerated cellulose films were produced via an ionic liquid process and combined with the excellent properties of titanium dioxide (TiO2) particles to prepare highly light-scattering and UV-absorbing composite film materials. Films with varying TiO2 loadings were cast onto plastic supports and regenerated in water. The resultant TiO2-regenerated cellulose films exhibited homogenous particle dispersion throughout the materials, while some particle size differentiation was observed with scanning electron microscopy, confocal microscopy, energy dispersive X-ray spectroscopy and elemental mapping. Remarkably, the Elrepho spectrophotometer and UV–Vis transmittance and absorbance results confirmed excellent scattering properties for the high-doped TiO2 films in the visible light wavelengths (80%→10% reduction in light transmittance), while complete UV light blocking was achieved even with very low (>0.5–1%) TiO2 addition levels. Furthermore, the TiO2-doped cellulose films also exhibited capabilities for UV activation. TiO2 loading also increased forward and backward scattering of the films, and the laser beam heating rate of the films was affected by both the doping level and thickness of the films. The developed composite material exhibited excellent light-scattering properties with UV shielding capabilities, confirming the potential of the composite for such advanced purposes as photoelectronic, agricultural or packaging applications.