Researchers at the University of Southern California's Viterbi School of Engineering have developed self-healing 3D printed rubber materials that enable rapid manufacturing that can be self-healed by cracking or piercing. This material will revolutionize the manufacturing of footwear, tires, soft robots and even electronic equipment, reducing manufacturing time and increasing product life.

The new materials are manufactured using a photopolymerization-based 3D printing process that cures the liquid resin material to the desired pattern or shape by light. 3D printing uses elastomeric inks with thiol and disulfide groups, in which thiol groups promote photopolymerization of thiol-enes during additive manufacturing, and disulfide groups achieve disulfide during self-healing processes Metathesis reaction. The researchers found that by adding an oxidizing agent during the photopolymerization process, the thiol begins to convert to a disulfide chemical group. The disulfide can be reconstituted during the crushing to achieve self-healing. The researchers pointed out that the ratio between the two sets of materials is the key to achieving self-healing capabilities. When the oxidant gradually increases, the self-healing behavior becomes stronger, but the photopolymerization behavior becomes weak, and there is competition between the two behaviors. The researchers found and tested the ratio of highly self-healing and relatively fast photopolymerization. In just 5 seconds, you can print a 17.5 mm square and complete the entire object in about 20 minutes. After the damage, you can repair it in a few hours. The researchers demonstrated the performance of this material on a range of products, including insoles, soft robots, multiphase composites and electronic sensors. It has been verified that the material healing time can be reduced only by raising the temperature. The material is completely healed after being cut in half and placed in a 60 ° C environment for two hours, and the strength and function are maintained.

The researchers pointed out that at different temperatures (40 ° C ~ 60 ° C), the material healing rate is close to 100%, by changing the temperature, you can control the healing rate, even at room temperature, the material can still repair itself. After implementing 3D printable soft materials, researchers are developing other self-healing materials of varying hardness, from existing soft rubbers to rigid hard plastics, which can be used in vehicle parts, composites, and even body armor.