Nanoparticle Coating For Glass Could Keep Car Cabins Cool | Chemical & Engineering News
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Web Date: September 24, 2013

Nanoparticle Coating For Glass Could Keep Car Cabins Cool

Materials Science: A new thin film containing indium tin oxide particles absorbs infrared light but is 80% transparent to visible light
Department: Science & Technology
News Channels: Materials SCENE, Nano SCENE
Keywords: glass coating, indium tin oxide nanoparticles, ITO, infrared light
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Sun Shield
A transparent silica film containing nanoparticles of indium tin oxide prevents infrared light from shining through glass. The percentages of tin in the films are shown above each piece of glass. Particles containing 10% tin absorb the most IR light.
Credit: ACS Appl. Mater. Interfaces
Photo of glass pieces coated in a silica film that absorbs infrared light
 
Sun Shield
A transparent silica film containing nanoparticles of indium tin oxide prevents infrared light from shining through glass. The percentages of tin in the films are shown above each piece of glass. Particles containing 10% tin absorb the most IR light.
Credit: ACS Appl. Mater. Interfaces

Sunlight streaming through a car’s windows can make the temperature inside the cabin unbearable without air conditioning. A new transparent coating for glass made from metallic nanoparticles could help save energy used to keep car interiors cool by absorbing infrared light hitting the windows (ACS Appl. Mater. Interfaces 2013, DOI: 10.1021/am403011t).

Materials scientists have experimented with several types of coatings to block infrared light, each with a drawback that prevents them from reaching commercialization. Thin films of indium tin oxide (ITO) are transparent to visible light but absorb infrared radiation. Unfortunately, ITO films also block radio waves that carry calls and data to cellphones, making the materials impractical for car windows. To let radio waves in, some researchers turned to coatings with nanoparticles of ITO embedded in organic polymers. However, these coatings are not hard enough to withstand the wear and tear produced by car power windows. A silica-based coating containing ITO nanoparticles is stronger, but it requires high temperatures to manufacture.

Kiyofumi Katagiri of Hiroshima University, in Japan, and his colleagues wanted to develop a strong nanoparticle-based material that could be made at a lower temperature. They first coated indium tin oxide nanoparticles containing 10% tin in octanoic acid. The researchers then suspended the hydrophobic nanoparticles in a silicon-containing polymer, perhydropolysilazane (PHPS). They spin-coated 10 layers of this mixture onto a glass surface and exposed the glass to ammonia vapor at 50° C to convert the PHPS into a silica polymer. The ITO nanoparticles end up embedded in the silica.

The resulting 0.75-μm-thick material is 80% transparent to visible light and absorbs 100% of infrared light at wavelengths longer than 1,400 nm. A silica-based coating containing ITO nanoparticles made by another group was thicker—about 2 μm—and blocked only infrared wavelengths longer than 1,600 nm. Absorbing a wider range of infrared light should keep a car cabin cooler, Katagiri says. The new material’s hardness is comparable to silica films without nanoparticles, so it should withstand the repeated forces created by power windows. Katagiri says one of his material’s limitations is that PHPS is expensive.

Hiromitsu Kozuka, a materials scientist at Kansai University, in Japan, says the straightforward processing at low temperatures and ambient pressure could make this coating practical for car windshields. But he points out that although exposing small pieces of glass to ammonia vapor is simple on a lab scale, on a large scale, it may be difficult to produce reproducible coatings.

 
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Comments
Lewis Goudy (January 5, 2014 4:17 PM)
Unfortunately, ITO films also block radio waves that carry calls and data to cellphones, making the materials impractical for car windows.

"The DoT is evaluating tech that would disable cell phones by drivers to reduce the number of distracted driving deaths.
- Roughly 5,500 people died from distracted driving last year.
- The Department of Transportation is considering disabling cell phones inside cars.
- Laws are unlikely to change behavior, contend some experts.

In addition to its efforts to educate drivers about the dangers of distracted driving, the U.S. Department of Transportation is evaluating technology that would disable cell phones in automobiles. The move is a response to the growing number of deaths and injuries related to distracted driving.

"There's a lot of technology out there now that can disable phones and we're looking at that," Raymond LaHood, the Secretary of Transportation said during a discussion during MSNBC's "Morning Joe."

LaHood said that nearly 5,500 people died from distracted driving last year, and that about half a million were injured. That's a low estimate, according to Paul Atchley, a scientist at the University of Kansas who studies distracted driving.
LaHood's figures only account for known deaths or injuries -- suspected deaths or injuries aren't included. The real numbers, said Atchley, are likely far higher, and will only get higher.

http://news.discovery.com/autos/cell-phones-driving-texting.htm



Kash (November 29, 2014 2:52 PM)
Use it for solar panels? Solar panels lose 20-30% of there yield from heat loses. A solar panel operating in ambient temperature of 30 deg c, has a cell temp of over 60 deg c. Would this coating work on keeping the temperature down? If so you could potentially increase profits from solar panels by 20%!!!!!!!!!
OSAMA ELBAYOUMI (January 9, 2014 6:18 PM)
1-prepare borosilicate glasses containing certain crystalizing agent. Expose the glass under certain conditions like temperature and proper atmosphere for a specific time schedule to produce nano particles.pant
the choice of the crystalizing agent will depend on the desired properties e.g. solar storage, electrochromic and/ or photochromic.

2- To use the glass as cured pant sol gel technology can be used to prepare the glass matrix with its crystallizing dopants

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