Interfacial transport-coupled covalent immobilization enables oxygen-tolerant and low-migration UV photopolymerization

A series of fluoroalkyl-functionalized and polymerizable photoinitiators were designed by integrating interfacial enrichment and covalent anchoring into a single molecular platform. • Fluoroalkyl segments induce spontaneous interfacial enrichment, thereby effectively enhancing resistance to oxygen inhibition during UV photopolymerization. • Polymerizable double bonds enable covalent incorporation into polymer networks, significantly suppressing post-curing migration of residual photoinitiators. • A structure, property, and kinetics relationship dependent on fluorine content was established, providing design principles for high-performance photoinitiators. UV photopolymerization is widely used in coatings, 3D printing, and biomedical materials due to its high efficiency and low energy consumption. However, Irgacure 2959, a representative Type I photoinitiator, suffers from oxygen inhibition and migration of residual species, limiting its practical applications. Herein, Irgacure 2959 was used as a molecular scaffold and structurally modified to construct a series of fluoroalkyl-functionalized polymerizable derivatives (2959-IA-nF, n  = 0–5) by introducing vinyl polymerizable groups and tunable fluoroalkyl segments, enabling coupled interfacial transport and covalent immobilization. The effects of fluorine content on photolysis behavior, interfacial migration, oxygen tolerance, polymerization kinetics, and extraction stability were systematically investigated. All fluorinated derivatives exhibit higher photolysis rates than Irgacure 2959. Driven by reduced surface energy, 2959-IA-nF spontaneously migrates to the gas-liquid interface, with increasing migration flux as fluorine content rises, thereby mitigating oxygen inhibition. Polymerization kinetics show a volcano-type dependence on fluorine content, with 2959-IA-3F exhibiting the highest apparent rate constant (0.1209 s −1 ), approximately threefold that of 2959. Vinyl groups enable covalent incorporation into the polymer network, reducing extraction in acetonitrile from 21.43% to <1.5% and decreasing aqueous UV absorbance by over one order of magnitude. Density functional theory reveals lower excitation free energy for 2959-IA-3F, facilitating intersystem crossing and efficient photolysis despite a higher cleavage barrier. The cured films exhibit reduced yellowing, tunable hydrophobicity, and improved elongation at break. This work demonstrates a coupled interfacial transport-reaction strategy for oxygen-tolerant, low-migration photoinitiators. Download: Download high-res image (159KB) Download: Download full-size image