Ultrafast Epoxy–Amine Photopolyaddition

Abstract

A new generation of light-induced production of polymeric materials is presented here. In detail, we propose to use photoacidic catalysis during the well-known epoxy–amine polyaddition reaction: it is now referred to as “epoxy–amine photopolyaddition”. Soft irradiation (405 nm visible light, 150–450 mW/cm2) of a photosensitizer/iodonium salt system leads to the production of superacids (e.g., H+, PF6–) that spectacularly enhance state-of-the-art epoxy–amine polyaddition kinetics: <3 min is necessary to obtain full conversion when >3 h is required to complete the reaction without light. Also, photoactivation greatly enhances final epoxy and amine conversions which resulted in increases (+15 °C) of the glass transition temperature of the final 3D polymer networks. This work clearly shows the extremely versatile applications for epoxy–amine photopolyaddition: thin layers (40 μm), thick layers (up to 2.5 cm), and composites (45 wt % fillers). This work paves the path toward ultrafast production of epoxy–amine composites and adhesives.