Strategies for the design of sustainable photocatalysts for radiation curing

 
Sustainable Carbon Nanodots (CDs) have received increased attention as photocatalyst in the field of ATRP since 2020. Biomass derived f.e. fr. lac dye, alginate, cellulose, hemicellulose, and citric acid served as raw material to make the CDs. Their different origin resulted in different efficiencies for the photo-ATRP using as metal catalyst either (Cu/TPMA)Br2 or FeBr3 at the ppm scale. Alternatively, a metal free approach also successfully worked with confined CDs obtained from cellulose in a silica network. Formation of the triplet state connects the system to a metal free photo-ATRP reaction protocol while systems with no efficient triplet formation failed. Alternatively, hydrothermal treatment of furfural available from hemicellulose provided CDs with aldehyde groups. This material resulted in porphyrin-based organic network comprising sustainable carbon dots. The polymers obtained exhibited a different dispersity of molecular weight depending on the biomass origin of the CD. Formation of block copolymers also succeeded. This approved control of chain termination. Free radical photopolymerization complements the pattern. The low cytotoxicity of the CDs was also remarkable.