The repair process, in which solvent-filled microcapsules embedded in an epoxy matrix rupture when a crack forms, is a major improvement over the original self-healing process first described in February 2001.
“While our previous solvent worked well for healing, it was also toxic,” said Scott White, a professor of aerospace engineering and a researcher at the university’s Beckman Institute. “Our new solvent is both non-toxic and less expensive.”
During normal use, epoxy-based materials experience stresses that can cause cracking, which can lead to mechanical failure. Autonomic self-healing – a process in which the damage itself triggers the repair mechanism – can retain structural integrity and extend the lifetime of the material.
Designed to mimic the human body’s ability to repair wounds, self-healing materials release a healing agent into the crack plane when damaged, and through chemical and physical processes, restore the material’s initial fracture properties.
In November 2007, White and collaborators reported the use of chlorobenzene, a common – but toxic – organic solvent, which in epoxy resins achieved a healing efficiency of up to 82 percent.
In their latest work, which combined a non-toxic and Kosher-certified food additive (ethyl phenylactate) and an unreacted epoxy monomer into microcapsules as small as 150 microns in diameter, the researchers achieved a healing efficiency of 100 percent.
“Previously, the microcapsules contained only solvent, which flowed into the crack and allowed some of the unreacted matrix material to become mobile, react and repair the damage,” said graduate research assistant Mary Caruso. “By including a tiny amount of unreacted epoxy monomer with the solvent in the microcapsules, we can provide additional chemical reactivity to repair the material.”
When the epoxy monomer enters the crack plane, it bonds with material in the matrix to coat the crack and regain structural properties. In tests, the solvent-epoxy monomer combination was able to recover 100 percent of a material’s virgin strength after damage had occurred.
“This work helps move self-healing materials from the lab and into everyday applications,” said graduate research assistant Benjamin Blaiszik. “We’ve only begun to scratch the surface of potential applications using encapsulated solvent and epoxy resin.”
In addition to White, Caruso and Blaiszik, the other co-authors of the paper were materials science and engineering professor Nancy Sottos and chemistry professor Jeffrey Moore. The researchers reported their findings in the scientific journal Advanced Functional Materials.
The work was supported by the U.S. Air Force Office of Scientific Research and the U.S. Department of Defense. Some of the work was performed at the university’s Center for Microanalysis of Materials, which is partially supported by the U.S. Department of Energy.
Editor’s note: To reach Scott White, call 217-333-1077; e-mail: firstname.lastname@example.org
James E. Kloeppel | University of Illinois
Researchers devise microreactor to study formation of methane hydrate
23.08.2017 | NYU Tandon School of Engineering
Meter-sized single-crystal graphene growth becomes possible
22.08.2017 | Science China Press
Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.
As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...
Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.
Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...
For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.
While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...
An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.
The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...
A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.
Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...
16.08.2017 | Event News
04.08.2017 | Event News
26.07.2017 | Event News
24.08.2017 | Life Sciences
24.08.2017 | Life Sciences
24.08.2017 | Medical Engineering