Highly stretchable dual‐cure photosensitive resin for digital light processing printing

The two-stage curing approach is one of the promising strategies to achieve the 3D printing of high-performance elastomers. Herein, a novel resin formulation that is composed of a photocurable acrylic resin and a mixture of thermocurable isocyanate oligomer/diamine is evaluated by digital light processing technology. Such resin possesses a satisfying viscosity for printing, especially at ambient temperature. For first curing stage, that is, photocurable stage, precisely architectural components with the required shape can be fabricated by a free-radical photopolymerization. Methyl ethyl ketone oxime that serves as a blocking agent, was employed to ensure the stability of isocyanate resin during this stage. Consecutively, a thermally activated deblocking process is carried out and accompanied by isocyanate/diamine copolymerization, which is the second curing stage. An interpenetrating polymer networks structure in designing resin (25 wt% photocurable resin and 75 wt% thermocurable resin) was formed after thermal curing, which is of significance for achieving excellently comprehensive mechanical properties. Contributed by special structures, it is capable of reaching a 4.67 MPa of tensile strength at 100% strain, while yielding favorable tensile strength of 7.51 MPa as well a maximum elongation at break of 745.3%, which is nearly identical to the initial mechanical performances of pure polyurethane elastomer.