Damage-reporting polymeric materials
If you've never had the plumber to your house, you've been lucky. Pipes can burst due to a catastrophic event, like subzero temperatures, or time and use can take a toll, wearing away at the materials with small dings and dents that aren't evident until it's too late.
Colorless, non-fluorescent microcapsules use a type of fluorescence called aggregation-induced emission (AIE), which becomes brighter as the indicator solidifies from solution and is visible under ultraviolet (UV) light.
Credit: Autonomous Materials Systems Group, Beckman Institute for Advanced Science and Technology, University of Illinois
But what if there were a way to identify those small, often microscopic failures before you had to call for help?
The Autonomous Materials Systems (AMS) Group at the Beckman Institute for Advanced Science and Technology has recently found a new way to identify microscopic damage in polymers and composite materials before total failure occurs.
"Autonomous indication of small cracks has exciting potential to make structures safer and more reliable by giving time to intervene and repair or replace the damaged region prior to catastrophic failure," said Nancy Sottos, professor of materials science and engineering, and one of the authors of "A Robust Damage-Reporting Strategy for Polymeric Materials Enabled by Aggression-Induced Emission," recently published in ACS Central Science. The paper is part of a research project selected as a finalist for the Institution of Chemical Engineers (IChemE) Global Awards 2016.
The researchers sequestered fluids containing turn-on fluorescence indicators in microcapsules, and then incorporated them into polymeric materials.
"We've developed microcapsules that are colorless and non-fluorescent when intact," said Maxwell Robb, Beckman Institute Postdoctoral Fellow and a lead author on the paper. "We can embed them into materials, and when damage occurs, the microcapsules will release their payload and become fluorescent, indicating that repair is needed."
Previous work led by Wenle Li, a postdoctoral research associate and co-first author of the study, had investigated another type of indicator within microcapsules, which underwent a chemical reaction upon release to produce a color change. However, the nature of the chemical reaction limited the system to a narrow range of materials.
The new method uses a type of fluorescence called aggregation-induced emission (AIE), which becomes brighter as the indicator solidifies from solution and is visible under ultraviolet (UV) light. The unique mechanism of indication, which relies on a physical change of state instead of a chemical reaction, enables excellent performance in a wide variety of materials and for visualizing different types of damage.
"The elegance of this system lies in its versatility as well as its sensitivity," said Li. "We can easily visualize a fluorescence signal resulting from mechanical damage as small as two microns."
The research is funded by BP, which is interested in coating oil and gas pipelines with a polymer coating that will be able to indicate damage. The goal is to target damage at its earliest stage to prevent further deterioration, improve safety and reliability, and reduce life cycle costs associated with regular maintenance and inspection.
Using instruments in Beckman's Microscopy Suite, the group was able to study the microcapsules and coatings of various materials, image them, and correlate the fluorescence signals to 3D structures of the damaged coatings.
"This is incredibly interdisciplinary work," said Robb. "Having knowledge about the aggregation-induced emission effect, and being able to design the chemistry of the microcapsule system was the starting point. Then there is the actual application of this technology into materials and coatings, which relies heavily on the expertise within materials science and engineering."
The AMS Group includes Sottos, Jeffrey Moore, professor of chemistry, and Scott White, professor of aerospace engineering, who also co-authored the study. Their work has led to new discoveries in self-detecting and self-healing materials.
"To impact the coatings industry, materials with self-reporting capability must meet a few criteria: they must be simple, not change the way the materials are traditionally applied, and perform just as well," said Moore. "Our approach hits this target - the new self-reporting function is realized by just one simple additive."
The next steps for this research are to combine damage indication with self-healing materials.
"If you could couple this technology that lets you know that damage has occurred with a self-healing material that tells you when the damage has been healed, it could be really powerful," said Robb.
"We have developed both turn-on fluorescence and color-changing indication systems. Our vision is to combine these multi-channel strategies to enable materials that monitor their mechanical integrity throughout the entire polymer lifecycle," said Li.
Maeve Reilly | EurekAlert!
In borophene, boundaries are no barrier
17.07.2018 | Rice University
Research finds new molecular structures in boron-based nanoclusters
13.07.2018 | Brown University
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
17.07.2018 | Information Technology
17.07.2018 | Materials Sciences
17.07.2018 | Power and Electrical Engineering