Urethane acrylate-based photosensitive resin for three-dimensional printing of stereolithographic elastomer

Three-dimensional (3D) printing elastomers have received wide attention because of their wide applications in many fields. In this work, we report a urethane acrylate-based photosensitive resin compound for 3D printing whose cured materials are elastic. This resin consists of bifunctional urethane acrylate (Royji 426 as the main matrix, monofunctional urethane acrylate (Royji 425), and isobornyl methacrylate (IBMA) as the diluents, trimethylolpropane triacrylate (TMPTA) as the crosslinker, phenylbis(2,4,6-trimethylbenzoyl)-phosphine oxide (819) and 2-hydroxy-2-methyl propiophenone (1173) as photoinitiators. The results indicate that the mechanical properties of cured materials can be tuned by adjusting the content of different components, but it is also accompanied by the changes in viscosity and volume shrinkage. Real-time Fourier transform infrared spectroscopy was employed to explore the relationship between the photoinitiators and the rate of initiation, and then found the best photoinitiators formulation. The resultant resin exhibits tensile strength of 7.46 MPa, elongation of 180.6%, viscosity of 978.53 mPa·s at 25°C and the volume shrinkage rate of 4.15%. Some complicated structures can be printed with the photosensitive resin such as C₆₀, hollow ball, wrist strap, and porous lattices. These architectures have excellent dimensional accuracy and can undergo any large deformation without damage. This manifested that this resin can provide a solution for existing 3D printing of elastomers.