Researchers from USC’s Viterbi School of Engineering have developed 3D printed rubber materials that self-heal and repair by themselves.
The team led by assistant professor Qiming Wang contends that their material can be manufactured quickly and repairs itself once fractured or punctured.
Such a material would definitely be a boon to industries like shoes, tires, soft robotics, and even electronics.
The USC material is manufactured using a 3D printing method that uses photopolymerization.
Photopolymerization is achieved through a reaction with a certain chemical group called thiols.
By adding an oxidizer to the equation, thiols transform into another group called disulfides.
It is this disulfide group that enables reformation when broken, leading to the material’s self-healing ability.
According to the researchers, finding the right ratio between these two groups was key to unlocking the materials’ unique properties.
“When we gradually increase the oxidant, the self-healing behavior becomes stronger, but the photopolymerization behavior becomes weaker,” explained 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.”
The researchers were able to print a 17.5-millimeter square in just 5 seconds, completing whole objects in around 20 minutes that self-repair themselves in just a few hours.
As part of their study, the team demonstrate their material’s ability on a range of products, including a shoe pad, a soft robot, a multiphase composite, and an electronic sensor.
After being cut in half, in just two hours at 60 degrees they healed completely, retaining their strength and function.
“We have actually shown that under different temperatures – from 40 degrees Celsius to 60 degrees Celsius – the material can heal to almost 100 percent,” said first-author of the study, Kunhao Yu.
“By changing the temperature, we can manipulate the healing speed, even under room temperature the material can still self-heal”
The researchers are now working to develop different self-healing materials along a range of stiffnesses, from the current soft rubber, to rigid hard-plastics.
They contend that such materials could be used for vehicle parts, composite materials, and even body armor.
Image and content: An Xin, Kunhao Yu/University of Southern California