Publications : 2015

Naphthalimide derivatives (NDAs) with amino- or alkylthio-substituents have been synthesized and combined in photoinitiating systems (PIS) with an iodonium salt, N-vinylcarbazole, an amine, or 2,4,6-tris(trichloromethyl)-1,3,5-triazine to produce radicals, cation radicals, or cations. The photochemical mechanisms are investigated by fluorescence, cyclic voltammetry, laser flash photolysis, electron spin resonance spin trapping, and steady state photolysis techniques. The generated reactive species are capable of initiating the cationic polymerization (CP) of epoxides under air or the free radical polymerization (FRP) of acrylates in laminate upon exposure to visible lights delivered by a halogen lamp, a cold white light-emitting diode (LED), or LEDs at 385, 395, 405, 455, or 470 nm. Compared to the well-known camphorquinone based systems, the novel NDA containing PISs exhibit higher efficiencies both for CP and FRP. Remarkably, the photobleaching of some NDAs is significant, and colorless final polymer coatings are obtained. The structure/photochemical property relationships of NDAs are discussed in detail (redox potentials, fluorescence, rate constants of reactions, etc.) to shed some light on their respective photoinitiating ability.

Naphthalimide-phthalimide derivatives (NDPDs) have been synthesized and combined with an iodonium salt, N-vinylcarbazole, amine or 2,4,6-tris(trichloromethyl)-1,3,5-triazine to produce reactive species (i.e., radicals and cations). These generated reactive species are capable of initiating the cationic polymerization of epoxides and/or the radical polymerization of acrylates upon exposure to very soft polychromatic visible lights or blue lights. Compared with the well-known camphorquinone based systems used as references, the novel NDPD based combinations employed here demonstrate clearly higher efficiencies for the cationic polymerization of epoxides under air as well as the radical polymerization of acrylates. Remarkably, one of the NDPDs (i.e., NDPD2) based systems is characterized by an outstanding reactivity. The structure/reactivity/efficiency relationships of the investigated NDPDs were studied by fluorescence, cyclic voltammetry, laser flash photolysis, electron spin resonance spin trapping, and steady state photolysis techniques. The key parameters for their reactivity are provided. (c) 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015, 53, 665-674

Four different 2-amino-1H-benzo[de]isoquinoline-1,3(2H)-dione derivatives (NDNs) bearing nitro-or amino-substituents have been prepared and incorporated into photoinitiating systems together with an iodonium salt, N-vinylcarbazole, an amine or 2,4,6-tris(trichloromethyl)-1,3,5-triazine. The ring-opening cationic polymerization of epoxides as well as the free radical polymerization of acrylates upon exposure to various visible LEDs (e.g. LEDs at 405 nm, 455 nm or 470 nm) could be performed. Reactions under green or red light (e.g. laser diodes at 532 or 635 nm) are also feasible. Compared to the well-known camphorquinone-based systems, some of the novel NDN-based combinations employed here exhibit a much higher polymerization efficiency. A panchromatic behavior can also be observed with a specifically designed compound bearing two nitro groups (e.g. radical polymerization or thiol-ene processes can be promoted upon blue, green or red light). This outstanding performance paves the way to polymerization under soft conditions. Their photochemical properties and structure/efficiency relationships have been investigated using steady state photolysis, fluorescence, cyclic voltammetry, laser flash photolysis, and electron spin resonance spin trapping techniques.