A 3D-printed, self-healing rubber material has the potential to be “game-changing” for soft robotics, electronics, shoes and more, by dramatically improving the lifespan of products.
Developed by researchers at the University Of Southern California Viterbi School Of Engineering, the material can repair itself when torn or punctured, regaining the same strength properties it had before being damaged.
It is created using a type of 3D printing known as photopolymerization. Instead of using the heat-melted filament found in home 3D printers, it instead harnesses light to solidify liquid resin into the required shape.
In order to create the self-healing rubber material, the engineers tweaked the underlying chemical reaction involved by adding an oxidiser. This changed the chemical group involved in the reaction, introducing the repairing properties.
“When we gradually increase the oxidant, the self-healing behavior becomes stronger, but the photopolymerization behavior becomes weaker,” explained University Of Southern California Viterbi School Of Engineering assistant professor Qiming Wang.
“There is competition between these two behaviors. And eventually we found the ratio that can enable both high self-healing and relatively rapid photopolymerization.”
While the material can self-heal at room temperature, applying heat speeds up the repair process significantly.
At 60°C, a sample of the material that had been cut in half takes less than two hours to completely heal, regaining all strength and function.
“We actually show that under different temperatures – from 40°C to 60°C – the material can heal to almost 100%,” said study first author Kunhao Yu, a structural engineering student in the department.
“By changing the temperature, we can manipulate the healing speed, even under room temperature the material can still self-heal.”
Fast manufacturing for soft robotics, shoes and beyond
In addition to the self-healing properties, the 3D printed nature of the material means it can be manufactured into desired structures very quickly.
A 17.5mm square, for example, takes just 5 seconds to produce.
This, combined with the healing properties, gives the material significant potential within a host of industries.
In soft robotics, it could allow for hard-wearing soft robots capable of working alongside humans in a host of industries.
By contrast, in footwear it could allow custom shoes to be rapidly produced, which would then last well beyond current equivalents.
It also has the potential to be used for tyres, reducing vehicle operating costs.
The researchers are also working to develop other types of materials with the same self-healing properties, focusing on hard plastics. These could pave the way for vehicle parts that can be repaired at dramatically lower costs than current versions, or even body armour that can heal after taking damage.