NIR‐Sensitized Cationic and Hybrid Radical/Cationic Polymerization and Crosslinking

NIR‐sensitized cationic polymerization proceeded with good efficiency, as was demonstrated with epoxides, vinyl ether, and oxetane. A heptacyanine functioned as sensitizer while iodonium salt served as coinitiator. The anion adopts a special function in a series selected from fluorinated phosphates (a: [PF(6)](−), b: [PF(3)(C(2)F(5))(3)](−), c: [PF(3)(n‐C(4)F(9))(3)](−)), aluminates (d: [Al(O‐t‐C(4)F(9))(4)](−), e: [Al(O(C(3)F(6))CH(3))(4)](−)), and methide [C(O‐SO(2)CF(3))(3)](−) (f). Vinyl ether showed the best cationic polymerization efficiency followed by oxetanes and oxiranes. DFT calculations provided a rough pattern regarding the electrostatic potential of each anion where d showed a better reactivity than e and b. Formation of interpenetrating polymer networks (IPNs) using trimethylpropane triacrylate and epoxides proceeded in the case of NIR‐sensitized polymerization where anion d served as counter ion in the initiator system. No IPN was formed by UV‐LED initiation using the same monomers but thioxanthone/iodonium salt as photoinitiator. Exposure was carried out with new NIR‐LED devices emitting at either 805 or 870 nm.