Near-infrared photopolymerization: Initiation process assisted by self-quenching and triplet-triplet annihilation of excited cyanine dyes

► The analysis of the dye photobleaching dynamics is achieved in situ into a droplet configuration. ► The photoinitiating properties of the dye stems from reactivity of its reduced and oxidized forms. ► In acrylate monomer, the reduced cyanine is responsible for the free radical photoinitiation. ► Addition of an amine accelerates the reaction due to the H-abstrator role the oxidized form. ► In this latter reactive pathway, the dye is ultimately regenerated.