The combination of thermally induced and photoinduced free radical polymerization of (meth)­acrylic monomers has only been scarcely presented in the literature. In this study, a two-component system with a near-infrared (NIR) dye combined with a thermal initiator is presented. The dye acts as a very efficient heat generator (heater) upon irradiation with NIR light. Several thermal initiators are presented such as an alkoxyamine (e.g., BlocBuilder-MA), azo derivatives, and (hydro)­peroxides. The heat delivered by the dye dissociates the thermal initiator, which initiates the free radical polymerization of (meth)­acrylates. Several types of heat generators are presented such as borate-based dyes and a silicon phthalocyanine derivative. For the first time, the effects of the NIR heater concentration, light intensity, and monomer structure on the heat released are studied using thermal imaging studies. NIR light curing is challenging but offers significant advantages: it is safer than shorter wavelength, and it allows a deeper penetration of the light and therefore a better curing of filled samples for a unique access to composites. Systems using a cyanine borate as a dye give high conversion rate of CC for methacrylate monomer under air. Two wavelengths of irradiation are studied: 785 and 850 nm. The presence of additives (phosphines or iodonium salts) can also improve the polymerization profiles.

Photopolymerization processes, and especially those carried out under visible light, are more and more widespread for their multiple advantages compared to thermal processes. In the present paper, new 1,8-naphthalimide derivatives are proposed as photoinitiators for free-radical polymerization upon visible light exposure using light-emitting diodes (LEDs) at 395, 405, and 470 nm. These photoinitiators are used in combination with both iodonium salts and phosphine. The synthesis of these compounds as well as their excellent polymerization initiation ability for methacrylate monomers are presented in this article. A full picture of the involved chemical mechanisms is also provided thanks to photolysis, radical characterization, and redox measurements.