Kinetic study of azidopentaammine cobalt(III) complex as photoinitiator and termination agent ofN-vinylpyrrolidone radical polymerization

Supramolecular encapsulation of redox-active monomers to enable free-radical polymerisation

“…Oxidative terminations have been previously observed in aqueous polymerisations of methyl methacrylate, styrenes and acrylonitriles that make use of redox initiator systems. 44–47 Another example by Das et al investigated the use of methylene blue as a retarder, with the primary radical being transferred to a methylene blue electron acceptor via oxidative termination, altogether supporting the outlined mechanism of our system (extended discussion see ESI, Section 1.4†). 48…”

Cobaltic accelerator for the methylene blue photoinitiation system in aqueous acrylate solution

“…It has been reported that some cobaltic complexes such as azidopentammine cobalt(III) and diacidobis(ethylenediamine)cobalt(III) can independently act as photoinitiator in the photoinitiated polymerization of vinyl monomer in bulk or aqueous solution 17–19. However, a light source of short wavelength must be used in these investigations, and the deaeration is necessary before irradiation.…”

Photosensitizers and Photoinitiators

“…They observed that the reaction proceeds in the presence of air, but that coinitiators like amines, inhibit the reaction: Also their observations suggest that the monomer tends to aggregate in clusters containing the dye molecules. 155 The reaction proceeds at room temperature in an argon atmoslphere. 155 The reaction proceeds at room temperature in an argon atmoslphere.…”

“…154 An organometallic compound, azidopentaaminocobalt, was shown to be capable of initiating free-radical photopolymerization of N-Vinyl-2pyrrolidone in the presence of either ultraviolet or visible light. 155 The Co complex is photoreduced through a charge transfer process to the metal. 155 The Co complex is photoreduced through a charge transfer process to the metal.…”

“…155 The reaction proceeds at room temperature in an argon atmoslphere. 155 Garcia and coworkers , 156 reported a photoinitiating system that exhibits maximum sensitivity at 518 nm. This results in formation of cobaltous ions and azide radicals.…”