Keggin‐Type Polyoxometalate ([PMo₁₂O₄₀]³⁻) in Radical Initiating Systems: Application to Radical and Cationic Photopolymerization Reactions

Abstract

New photoinitiating systems based on a polyoxometalate (POM) are proposed: phosphomolybdic acid in combination with silane, germane, or iodonium salt can be used to generate silyl, germyl, or phenyl radicals as well as silylium cations. The photochemical mechanisms are studied by steady‐state photolysis and electron spin resonance. The phosphomolybdic acid/silane/iodonium salt system can initiate either the radical photopolymerization of acrylates or the cationic photopolymerization of epoxides. The synthesis of interpenetrated polymer networks can also be carried out. The mechanical properties of the synthesized polymers are affected by the presence of POM in the matrix, as shown by their dynamic mechanical analysis (DMA).

Visible light sensitive photoinitiating systems: Recent progress in cationic and radical photopolymerization reactions under soft conditions

“…As a consequence, HSiMo12/Iod/(TMS) 3 Si-H PIS exhibits the best efficiency for the CP of EPOX under the Xe-Hg lamp irradiation among all the investigated POMs (i.e., PMo12, HSiMo12 and NSiMo12) as shown in Fig. 8 [237][238][239].…”

“…Reproduced by permission of the American Chemical Society.PMo12 based PIS [PMo12/Iod/(TMS)3 Si-H] exhibits higher efficiency for the CP of EPOX than that of decatungstate under the Xe-Hg lamp exposure under air. The PMo12/Iod/(TMS)3 Si-H PIS can also initiate the FRP of TMPTA in laminate[239].Silicon polyoxomolybdates (HSiMo12 and NSiMo12) are also keggin-type POMs. Compared to PMo12, their…”

“…UV-vis absorption spectra of decatungstate, PMo12, HSiMo12 and NSiMo12 in acetonitrile[237][238][239]. Copyright 2011, 20,132,013, respectively.…”

Iodonium‐polyoxometalate and thianthrenium‐polyoxometalate as new one‐component UV photoinitiators for radical and cationic polymerization

“…Remarkably, these novel onium salts can be characterized by a higher reactivity than the corresponding diphenyliodonium hexafluorophosphate or the TH salt in CP. As previously reported, when using other POM containing systems, 41,42 the present novel compounds should likely ensure (but the demonstration is beyond the scope of this article) the in situ incorporation of the polyoxomolybdate/polyoxotungstate during the photopolymerization of the starting monomers. Such behavior is expected to be of interest for the fabrication of POM-polymer hybrid materials: this deserves to be studied in detail.…”

“…To the best of our knowledge, this has never been tried before in 41 all these compounds synthesized in this study (Scheme 1) can work as one-component cationic PIs under exposure to UV light. The photochemical generation of radicals will be studied using steady-state photolysis, cyclic voltammetry, and electron spin resonance spin trapping (ESR-ST) experiments.…”