Thioxanthone Skeleton-Based One-Component Macro-Photoinitiator Reduces Oxygen Inhibition and Migration Through Cooperative Effect.

The oxygen inhibition and migration of micromolecules which stem from photoinitiators (PIs) remain two critical challenges to address in radical photocuring. In this work, we reported a one-step ternary copolymerization strategy to construct a one-component macromolecular photoinitiator (PPI) using polymerizable thioxanthone (TX), amine (N), and fluorinated alkane (F) as monomers. Then, we utilize the low surface energy of F unit and macromolecular skeleton to reduce oxygen inhibition and migration. Compared to micromolecule TX, PPI also exhibits a broad absorption in the 250-430 nm range, and a higher molar extinction coefficient. The effects of the TX, N, and F component ratios on the photoinitiation efficiency of PPI were systematically investigated, and the photopolymerization kinetics revealed that the increased content of F unit can eliminate the oxygen inhibition of PPI. As a result, PPI demonstrates the more superior photoinitiation efficiency compared to the traditional TX/N two-component macromolecule photoinitiation system. Migration experiments indicated that there is a 60% reduction in the migration rate for PPI compared to the TX/N photoinitiation system. This work provides an effective strategy to address oxygen inhibition and micromolecule migration issues in radical photocuring, showing potential applications in food and pharmaceutical packaging fields.