N-[(1RS)-camphane-2-ylidene]aniline: A novel efficient liquid UV absorber for 3D printing

Objectives. To investigate the effectiveness of N-[(1RS)-camphanyl-2-ylidene]aniline as an ultraviolet (UV) absorber in 3D printing using digital light processing. Methods. Polymerization process parameters were determined using а Netzsch DSC 204 F1 Phoenix differential scanning calorimeter equipped with an OmniCure S2000 UV irradiation attachment (400–500 nm filter). Samples were printed on a Minicube ULTRA 3D printer using a 405-nm LED light source. Dimensional accuracy during printing was evaluated according to ISO 52902:2019. Mechanical properties were determined using a Zwick/Roell Zwicki Z5.0 universal testing machine, while heat deflection temperature was measured on a Gotech HDT-HV-2000-3 device. Results. The conversion degree of double bonds determined from differential scanning calorimetry results for a photopolymerizable composition containing camphor anil are almost identical to that for the composition without a UV absorber. The high gel fraction content in the samples indicates the formation of cross-linked polymers. The level of physical and mechanical properties, as determined in tensile and flexural parameters, is largely unaffected by the use of the type of UV absorbers considered. Tensile strength values are comparable to those of oligocarbonate methacrylate OСM-2-based materials produced under radiation polymerization conditions. Dimensional deviation for materials containing camphor anils is smaller than for compositions without a UV absorber or for compositions using a triazole derivative as an absorber. Conclusions. The effectiveness of camphor anils as UV absorbers in the photopolymerizable composition is confirmed. With high dimensional accuracy in printing, it is possible to produce densely cross-linked polymers offering desirable physicomechanical properties and heat deflection temperatures.