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 study presents novel photoinitiating systems based on diaryliodonium salt (IOD) and 1-amino-4-methyl-6-styrylnaphthalene-2-carbonitrile derivatives developed as universal IOD photosensitizers. These systems' spectroscopic characteristics, electrochemical behavior, and thermodynamic parameters were investigated to determine the optimal two-component photoinitiating system for light-initiated polymerization, including free-radical and cationic reactions. This versatility in initiating both types of reactions was utilized to explore the dilution effect of non-reactive and two different reactive (cationic, free-radical) diluents. The best formulation was chosen according to Fourier-transform infrared spectroscopy (FTIR), photorheology, thermogravimetric analysis (TGA), and dynamic mechanical analysis (DMA) and tested for the preparation of functional nanocomposites with two types of nanofiller: silver oxide (Ag2O) and hydroxyapatite (HA). The manufacturing process based on additive technology was analyzed according to FTIR spectroscopy and viscosity changes. The results show the high potential of the newly developed photosensitizers in practical applications and 3D-VAT printing.