Novel Copper Photoredox Catalysts for Polymerization: An In Situ Synthesis of Metal Nanoparticles

Abstract

The copper II complex (HLCuCl) carrying 2,4 dinitrophenylhydrazone (L) is synthesized and evaluated as a new photoredox catalyst/photoinitiator in combination with triethylamine (TEA) and iodonium salt (Iod) for the radical polymerization of ethylene glycol diacrylate during exposure to visible light using a photoreactor at 419 nm. The copper complex reactivity with TEA/Iod salt/gold chloride showed a good production and stability of gold nanoparticles. Finally, the high performance of Cu (II) complex for radical photopolymerization incorporating gold nanoparticles is provided. The photochemical mechanisms for the production of initiating radicals are studied using cyclic voltammetry. Polymer nanocomposites containing gold nanoparticles (Au NPs) in situ photogenerated during the irradiation process were prepared. The formation of Au NPs inside the polymer matrix was through UV–Vis and EDS/SEM analyses.

Efficacy Analysis of In Situ Synthesis of Nanogold via Copper/Iodonium/Amine/Gold System Under a Visible Light

“…A specific measured system was reported by Tar et al [21], in which their proposed kinetic (shown in Scheme 1) for a 3-component system of G1/Iod/amine, where G1 is a copper complex HLCuCl, amine can be TEA (itriethylamine), a reducing agents in the formation of gold nanoparticle inside the polymer matrix; and Iod is iodonium salt (oxidizing agent). The photoinitiating (PI) systems are mainly based on G1/TEA/Iodonium salt (0.05/1%/1% w/w) to the gold chloride (HAuCl4) added 4wt% in a few drops of DMF, and the PI system was dissolved in EGDA at 93.95 wt%.…”

“…Scheme 1, A proposed kinetics for a 3-component system of G1/Iod/amine in gold chloride (HAuCl4) solution, where Cu is for copper complex (HLCuCl), having an excited state Cu*, which couples with iodonium salt, Ar2I(+), and amine to produce radicals, (Ar 0 and amine 0 ) which lead to FRP. Both Cu* and amine 0 can couple with Au(3+) to form Au(2+), then Au(1+), leading to Au(0) and the nanogold [21].…”

“…The interaction of the G1, TEA and gold chloride was very fast, (within 60 s) under a visible light at 419 nm. After five minutes under irradiation, the absorption of the complex and Au +3 have entirely disappeared having an increase in absorption at the green (532 nm), which corresponds the surface plasmon resonance (SPR) absorption [21][22][23]. The peak absorption (at 532 nm) of nanogold (NG) in round shape moves toward near IR if the NG is in a bar shape (with a length ratio of 4.0) [24].…”

“…More recently, our group also report the novel copper photoredox polymerization for in situ synthesis of metal nanoparticles, Tar et al [21]. This article will present, for the first time, the kinetics and the general features of a photopolymerization system (under visible light), Copper/ Iodonium/ TEA/gold chloride based on the proposed mechanism of Tar et al [21]. Analytic formulas will be developed to explore the new features.…”

Efficacy Modeling of New Multi-Functional Benzophenone-Based System for Free-Radical/Cationic Hybrid Photopolymerization Using 405 nm LED

“…The efficiency of copper complex (G1) based photoinitiating systems (G1/iodonium salt (Iod)/Nvinylcarbazole (NVK) was investigated by Mokbel et al [16] for free radical polymerization (FRP) of acrylates and the free radical promoted cationic polymerization (CP) of epoxides using light source (LEDs at 375, 395, 405 nm, halogen lamp). Recently, our group also reported the novel copper photoredox polymerization for in situ synthesis of metal nanoparticles, Tar et al [21], and the associated efficacy and kinetic modeling, Lin et al [22].…”