“Aaaahhhhh. Someone keyed my car! *#!#@&*@%”
Car owners who have found their car scratched may have uttered some pretty colorful words immediately after this discovery because restoring the damage is notoriously difficult. But in the future, thanks to some research from polymer scientists involving nanostructures, such exclamations may change to: “Darn. Someone keyed my car. No worries. I can fix it when I get home.”
The change in tone and word choice may be attributed to a team of polymer scientists and engineers at the University of Massachusetts Amherst, who made nanostructures that can fill in and bind to tiny areas that have been damaged. The practical benefits include using less material to make repairs, rather than replacing an entire part or resurfacing an entire area.
“This is particularly important because even small fractures can then lead to structural failure but our technique provides a strong and effective repair,” says team leader and UMass Amherst polymer scientist Todd Emrick. “The need for rapid, efficient coating and repair mechanisms is pervasive today in everything from airplane wings to microelectronic materials to biological implant devices.”
Nano-scale damaged areas possess characteristics that are different from the undamaged areas near them, reports Plastics Infomart. Not only is the topography different on a nano-scale, but so are wetting characteristics, roughness, and chemical functionality. “If nanoparticles were held in a certain type of microcapsule, they would probe a surface and release nanoparticles into certain specific regions of that surface,” effectively allowing a spot-repair, Emrick says.
That kind of behavior is similar to how white blood cells act in a biological process. They probe, release their contents in a smart, triggered fashion, and then go elsewhere.
That characteristic is mimicked in the nanostructures. The researchers developed a method using polymer surfactant that stabilizes oil droplets in water capsules, which hold the nanoparticles very efficiently. The nanoparticles can be released when desired because the capsule wall is very thin. Polymers made into gels have been known to be flexible and contort in other ways as well.
“We then found that the nanoparticle-containing capsules roll or glide over damaged substrates, and very selectively deposit their nanoparticle contents into the damaged (cracked) regions,” Emrick says. “Because the nanoparticles we use are fluorescent, their localization in the cracked regions is clearly evident, as is the selectivity of their localization.”
The development can detect damaged substrates as well. Also, the encapsulation techniques make it easier to deliver hydrophobic objects in a water-based system, precluding the need for organic solvents in industrial processes that can cause harm to the environment, Emrick notes. “Having realized the concept experimentally, looking forward we now hope to demonstrate recovery of mechanical properties,” he says.
Source: “UMass Amherst Polymer Science Team Designs New Nanotech Technique for Lower-Cost Materials Repair,” Plastics Infomart, 1/13/12
Image by Athol Mullen.
Dale McGeehon has been a journalist and editor for more than 25 years, covering chemical regulation and testing for Pesticides and Toxic Chemical News and innovations in material sciences for the National Technology Transfer Center. His writing credits include Omni and College Park magazines and The New York Times.