Fluorescence monitoring of photoinitiated polymerization reactions: Synthesis, photochemical study and behaviour as fluorescent probes of new derivatives of 4′-dimethylaminostyryldiazines

The fluorescence emission of three new fluorescent probes has been studied in environments of different polarity and viscosity. The diazine moieties behave as electron acceptor and a good correlation has been found between their reduction potentials and the dipole moments in the excited state (estimated from solvatochromic plots using Lippert equations). The probes have shown to be sensitive to changes in both microviscosity and micropolarity of the surroundings. They have been used as fluorescent sensors to monitor the photopolymerization reactions of some mono- and difunctional methacrylate monomers in bulk. The fluorescence emission band of the probes showed an increase in intensity, as well as an hypsochromic shift, as the degree of conversion increases, throughout the entire polymerization range in the different systems checked.