'Warm-Blooded Plastic' Could Keep Homes Cozy Someday
A new material maintains its own temperature, no matter what the temperature is around it. In the future, self-regulating materials could go into self-warming windows, self-cooling computers and other devices.
CREDIT: 1971yes | Shutterstock.com
Thermostats and heating vents keep houses cozy now, but in the future perhaps the walls themselves will maintain a comfortable temperature, with self-regulating wallpaper.
Researchers have taken a step toward this, creating a small square of what looks like plastic wrap that can maintain its own temperature. Cool temperatures automatically trigger a chemical reaction that warms the plastic. When it gets too warm, the chemical reaction stops and the material cools. No matter the temperature outside, the material always keeps itself 88 degrees Fahrenheit (31 degrees Celsius) to 93 F (34 C).
The material's ability to regulate its own temperature is reminiscent of birds, mice and other so-called warm-blooded animals, its creators say. "So we also call it warm-blooded plastic," said Ximin He, a researcher at Harvard University who creates materials that mimic insects, leaves and other living things. She and her colleagues have named their new material Synthetic Homeostatic Smart Material, or SMARTS for short.
In the next few years, self-regulating materials could appear in the tiny, sophisticated devices scientists use to make chemical analyses, said Anna Balazs, a chemical engineer at the University of Pittsburgh who worked with He on the new material. Eventually, plastics and other materials that can maintain their own temperature, pH and other properties could be used in bigger objects, such as windows that stay warm and block the cold from coming in, cutting heating bills, He told InnovationNewsDaily. A constantly cool piece of plastic could be used in home and research computers instead of relying on air conditioners, she added. [10 Building Materials from the Future]
SMARTS uses a complex structure with three layers to maintain its temperature. At the bottom is a layer of tiny bristles that sit under two layers of fluid. The tips of the bristles are covered in chemicals that react with the chemicals in the top fluid layer.
When it's cooler than about 88 F, the bristles stand up, immersing their tips in the top fluid. "That turns the chemical reaction on and the fluid heats up," explained Olga Kuksenok, another University of Pittsburgh chemical engineer who worked on SMARTS.
Eventually the chemical reaction gets too hot, however. At about 93 F, the bottom fluid layer contracts, scrunching the bristles down and away from reactive top fluid. Without the bristles, the hot top fluid starts to cool. If the temperature drops below 88 F, the bottom fluid makes the bristles stand up again, starting the cycle over.
Most self-regulating systems now, such as home thermostat systems, have sensors to detect the temperature and a separate computing center that decides whether to blast hot or cold air in response. This new plastic changes temperature all by itself, without using electricity. "This senses the temperature and dynamically fixes it. It cuts out the middleman," Balazs said. "This is incredibly more energy efficient."
He said she and her colleagues now plan to try to make SMARTS materials that can maintain other characteristics, such as pH, pressure or glucose levels. The creators think they should be able to change what SMARTS responds to — or adjust SMARTS' temperature range — simply by changing the lower fluid in the material, which controls whether the bristles stand up or lie down.
"It's a very broad-based platform we have created that could basically be the blueprint for a broad range of other self-regulatory devices or materials," He said.
He, Balazs, Kuksenok and their colleagues' paper about SMARTS was published today (July 11) in the journal Nature.