Massachusetts Institute of Technology (MIT) researchers have recently identified a hydrogel material that could potentially be used for passive cooling and water harvesting in warmer climates. Commonly used in cosmetic creams, industrial coating and pharmaceutical capsules, Polyethylene glycol (PEG) can absorb moisture form the atmosphere even as temperatures climb. 
 
Due to PEG’s unique properties, researchers developed a model that can be used to engineer other water-absorbing, heat-resistant materials. The material could be incorporated into heat pumps and air conditioners to regulate temperature and humidity more efficiently. 
 
As temperatures rise from 25 to 50 degrees Celsius (77 to 122 degrees Fahrenheit), PEG doubles its water absorption. The resistance stems from a heat triggering transformation. As the hydrogel’s surroundings heat up, its microstructure morphs from a crystal to a less organized “amorphous” phase, enhancing PEG’s ability to capture water. 
 
“A huge amount of energy consumption in buildings is used for thermal regulation,” says Lanan Zhang, a research scientist at MIT. “This material could be a key component of passive climate-control systems.”