Abstract:Lignin from different technical sources were coated on the surface of titanium dioxide (TiO2) via one-step hydrothermal esterification reaction and nanoscale lignin/TiO2 composites were obtained. The results of DLS analysis showed that the particle size of TiO2 increased by 8-12 nm after modification. The mass fraction of lignin in the composites was 7.6%~9.0% by TG analysis. The esterification reaction that happened between the carboxyl groups of lignin and the hydroxyl groups on the surface of TiO2 was confirmed by XPS, and coated lignin could be observed by TEM. The lignin/composite nano composites were then used as the sole sunscreen component to prepare sun creams, and the sun protection factor (SPF) values of the sun cream was measured and compared with that of the sun cream containing same amount of TiO2 only. The results showed that TiO2 modified by organosolv lignin (OL) had the best sunscreen performance and the SPF values of sun creams containing mass fraction of 10% and 20% of OL/TiO2 reached to 44 and 73, respectively, which were much higher than that containing raw TiO2. In addition, the prepared sun creams had better feeling. which met the daily sun protection requirement. Finally, the UV-blocking enhancement mechanism of lignin/TiO2 was proposed.