University of Colorado at Boulder researchers have created a new, transparent insulating material that blocks heat while allowing light to pass through it.
Called MOCHI (Mesoporous Optically Clear Heat Insulator), the heat-blocking material could significantly reduce energy usage in building windows without compromising visibility. A transparent insulator could also replace “frozen smoke” aerogel insulators, which are typically cloudy rather than clear in industrial applications.
Although MOCHI is not yet commercially available, its CU Boulder developers said the ingredients used to make their transparent insulator are common and inexpensive. They also noted that its current complex manufacturing process could also be significantly optimized, raising the possibility that transparent insulators could be available sooner rather than later.
MOCHI Could Help Fill the Need for Transparent Insulators
In a statement detailing MOCHI’s development, Ivan Smalyukh, a CU Boulder professor of Physics, noted that a building’s walls, ceilings, and floors can be insulated to reduce heat exchange, thereby reducing the need for costly, carbon-intensive indoor environmental control systems. However, the professor notes, “windows need to be transparent.”
“Finding insulators that are transparent is really challenging,” he explained.
Still, the need for transparent insulators is continuing to grow. According to the team, the combined worldwide energy consumption of all buildings accounts for around 40% of total energy generated. Although some of that energy is used for lighting, wi-fi, data processing, and other applications, a significant portion of the overall usage comes from environmental control systems.
“No matter what the temperatures are outside, we want people to be able to have comfortable temperatures inside without having to waste energy,” said Smalyukh, who is also the senior author on a study detailing the team’s work.
Some semi-transparent insulators exist, with aerogels at the forefront of the industrial market. For example, NASA uses aerogels to keep electronics warm on several space missions. However, aerogel’s asymmetrical internal structure often renders it foggy rather than transparent, earning it the unofficial nickname “frozen smoke.”
Tiny Bubbles Give See-Through Material Its ‘Magical’ Properties
According to the team’s statement, the first step in creating MOCHI involved mixing surfactants into a liquid solution containing silicone particles. In this medium, surfactants bind together into strings, similarly to how oil does when separating from water. Next, the silicone particles attach to the threads’ surfaces. After the researchers put the surfactant threads through a chemical removal process, they are left with tiny tubes of silicone filled with air. The professor called this material, made up of tubes thinner than a human hair and more than 90% air, a “plumber’s nightmare.”
By fabricating the material into a thin sheet, they are left with a symmetrical array of tiny bubbles filled with gas that lets through about 98% of light. This level of transparency makes it significantly more versatile than aerogels filled with asymmetrical gas bubbles as window insulators.
During testing, the team found that their new material minimized heat transfer by preventing molecules from bouncing off one another and transferring energy. Professor Smalyukh said the key to MOCHI’s unique dual ability to allow light transfer while preventing heat transfer lies in its extremely tiny bubbles, which prevent these molecular collisions.
“The molecules don’t have a chance to collide freely with each other and exchange energy,” Smalyukh said. “Instead, they bump into the walls of the pores.”
Streamlining the Process and Theoretical Applications
The current process for producing the transparent insulator remains time-intensive, limiting its use to the lab setting. However, the research team noted, MOCHI’s ingredients are relatively inexpensive, and they also believe the complex manufacturing process “can be streamlined.” The professor said this combination “bodes well’ for MOCHI’s potential commercial uses.
When discussing the material’s possible commercial and industrial applications, the CU Boulder team noted that its superior heat-blocking ability allows it to be applied in sheets just 5 millimeters thick. In fact, the team said a sheet this thin has such a powerful insulating ability that you could “hold a flame in the palm of your hand” if MOCHI were to cover it.
In one extreme example, the researchers noted that their material is so good at blocking heat that you can use a MOCHI sheet just 5 millimeters thick to cover windows. They also note that MOCHI is long-lasting, making it well-suited for skyscrapers as well as residential homes.
Along with window-covering applications, the team suggested that their transparent insulator could be used in theoretical devices that trap sunlight’s heat and convert it into cheap, sustainable energy.
“Even when it’s a somewhat cloudy day, you could still harness a lot of energy and then use it to heat your water and your building interior,” Smalyukh suggested.
The study “Mesoporous optically clear heat insulators for sustainable building envelopes” was published in Science.
Christopher Plain is a Science Fiction and Fantasy novelist and Head Science Writer at The Debrief. Follow and connect with him on X, learn about his books at plainfiction.com, or email him directly at christopher@thedebrief.org.