Enhanced activity as polymerization photoinitiators of Rose Bengal and Eosin esters with an O-benzoyl-α-oxooxime group: The role of the excited state reactivity

Abstract

New Eosin and Rose Bengal ester with an O-benzoyl-a-oxooxime group were synthesized and evaluated as visible light photoinitiators for polymerization in the presence of an amine. The dyes EO-AO and RB-AO are clearly better photoinitiators, with higher Rp values, than the corresponding physical mixtures dye/acyloxime, or than the corresponding pure dyes. However, the relative efficiencies of the different dye/amine and dye/amine/AO mixtures show that if RB is better than EO in the binary mixture, the situation was reversed after addition of AO. The spectroscopic and electrochemical properties of the dyes were measured and the forecasts of thermodynamic calculations were confirmed by time resolved laser spectroscopy experiments which show that the species formed by reaction of the excited dyes eosin and RB with AO were not the same. One observes the dominating formation of the oxidized form of the acyloxime with eosin and its reduced form in the case of Rose Bengal which lead in the case of EO to a larger amount of radicals per photon absorbed and a better initiating efficiency.

Synthesis and characterization of latex nanoparticles using a visible-light photoinitiating system in reverse micelles

“…In the presence of electron donors such as tertiary amines, the negatively charged dye Eosin-Y (Eos) has been described as an efficient photoinitiator for the free radical polymerization of several monomers in homogeneous medium [24][25][26][27][28][29]. This PI has been used as an efficient photoinitiator for surface modification by surface-mediated polymerization [30].…”

Effect of coinitiator type on initiation efficiency of two‐component photoinitiator systems based on Eosin

“…Various compounds, such as amines (e.g., aliphatic amines,25–36 aromatic amines,25, 34, 37 amino‐monomers,38–42 amino‐polymers43), halogenated compounds,44–46 oxime esters,47, 48 iodonium cations,49–54 and other oxidizing or reducing agents,23, 24, 41, 55–61 have been reported in literature as effective coinitiators for Eosin/coinitiator systems. Eosin/amine systems were used most often, either alone or in combination with other coinitiators or UV photoinitiators 29, 42, 62, 63.…”

In Situ Photochemically assisted Synthesis of Silver Nanoparticles in Polymer Matrixes

“…This suggests that the formation of silver nanoparticles was promoted by the excited state of EO 2-and confirms the mediating role of MDEA. Thus, the sequence of reaction would involve first, an electron transfer from the amine to 3 EO 2-, and then a proton transfer within the ion pair formed between amine radical cation and Eosin radical anion (Jones & Chatterjee, 1988;Kepka & Grossweiner, 1971;Rele et al, 2004;Janata et al, 1994;Burget et al, 1999). Hence, the reaction should initially produce an -aminoalkyl radical and the conjugated acid of semi-reduced Eosin (EOH• 2-).…”