Photoprotective Composites of Phosphorylated Cellulose and Nanoscale Cerium Dioxide

This study presents the synthesis and comprehensive characterization of novel composite materials based on phosphorylated cellulose (PC) and nanocrystalline cerium dioxide. The composites were produced via solution casting under ultrasonic homogenization. Analysis by PXRD, SEM, and spectroscopy methods revealed that CeO2 nanoparticles (~6 nm) form uniform aggregates within the PC matrix. The proportion of the amorphous cellulose fraction in the final composites increased with the cerium dioxide content. The composites exhibit an absorption edge at 400–500 nm and pale yellow-beige coloration. In vitro testing (ISO 24443 international standard) confirmed their UV-protective capability, with SPF and UVAPF values correlating directly with CeO2 content. These biocompatible composites show promise for sustainable sunscreens and cosmetic pigments.