Naphthalene–stilbenes as effective visible-light sensitizers to study the effect of diluent and nanofillers on in situ photopolymerization and 3D-VAT printing process

This paper presents new photoinitiating systems based on diaryliodonium salt (IOD) and 1-amino-4-methyl-6-styrylphthalene-2-carbonitrile derivatives developed as universal IOD photosensitizers. The spectroscopic characteristics of these systems, electrochemical behavior and thermodynamic parameters were investigated to determine the optimal binary photoinitiating system for light-initiated polymerization, including free radical and cationic reactions. This versatility in initiating both types of reactions was used to study the effect of diluting non-reactive and two different reactive (cationic, free radical) diluents. The best formulation was selected based on Fourier transform infrared spectroscopy (FTIR), photoreology, thermogravimetric analysis (TGA) and dynamic mechanical analysis (DMA), and tested to prepare functional nanocomposites with two types of nanofillers: silver oxide (Ag2O) and hydroxyapatite (HA). The additive-based manufacturing process was analyzed for FTIR spectroscopy and viscosity changes. The results indicate the high potential of the newly developed photosensitizers in practical applications and 3D-VAT printing.