Visible-light photopolymerization activated by nanocarbon materials as photocatalysts

Although numerous photocatalysts, such as organic compounds and metallic complexes, have been systematically designed and synthesized for visible light-induced photopolymerization, their disadvantages, such as toxicity and poor water dispersibility, cannot be neglected in practical production. Hence, high-performance photoinitiators based on nanomaterials, such as carbon dots and carbon nitrides, have recently been reported due to their favorable characteristics of eco-friendliness, high biocompatibility, etc. In this review, carbon-family-based photocatalysts reported in the last five years are thoroughly discussed by the classifications in terms of their photoinitiation mechanisms, such as photoinduced electron transfer-reversible addition-fragmentation chain-transfer polymerization (PET-RAFT), atom transfer radical polymerization (ATRP), cationic polymerization (CP) and free radical polymerization (FRP). Carbon family materials play significant roles in the applications of visible light-induced photopolymerization, such as 3D printing and hydrogel materials fabrication. Specifically, they can not only initiate photopolymerization but also endow products with specific chemical or physical properties, e.g., nontoxic, economical, and facile synthesis routes. Finally, reports on newly developed carbon-family nanomaterials, such as silicon quantum dots, are introduced and discussed as perspectives for photopolymerization, which could inspire researchers in the relevant fields.