Multifunctional biphenyl derivatives as photosensitisers in various types of photopolymerization processes, including IPN formation, 3D printing of photocurable multiwalled carbon nanotubes (MWCNTs) fluorescent composites

A series of 2-(diethylamino)-4-(1-ethylpropyl)-6-phenyl-benzene-1,3-dicarbonitrile derivatives were investigated in terms of photosensitisation in various photopolymerization processes in UV-A and vis light conditions. A full spectroscopic analysis of the tested compounds was performed. In addition to excellent spectroscopic properties, these compounds enable highly efficient photopolymerization processes, including free-radical, cationic and hybrid photopolymerization. As proven by a real-time FTIR study, these photosensitisers allow the formation of both thin and thick layers from different monomers. Finally, the investigated 2-(diethylamino)-4-(1-ethylpropyl)-6-phenyl-benzene-1,3-dicarbonitrile derivatives were used to obtain multiwalled carbon nanotubes (MWCNTs) composites for which the degree of conversion was determined using real-time FT-IR and Photo-Differential Scanning Calorimetry (Photo-DSC). Selected derivatives were applied as photosensitisers in two-component photoinitiating systems, operating according to the mechanism of photo-oxidation and photo-reduction, for the preparation of photo-cured MWCNTs composites. The importance of the quantity of multiwalled carbon nanotubes (MWCNTs) added to the polymeric matrix on the curing degree is also discussed in this study. The structures of the MWCNTs composites were analysed using an optical and fluorescence microscope. Moreover, this study also examines the applicability of new photoinitiator systems for printing nanocomposites by vat photopolymerization, which has gained increasing attention in recent years. Therefore, photocurable nanocomposite resin based on methacrylates was used for 3D printing in room temperature and atmospheric conditions, under a visible LED with emission at 405 nm, in order to obtain fluorescent photocurable patterns.