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New blue repels heat, won’t fade
A brilliant new blue pigment – discovered almost by accident by Oregon State University (OSU)chemists in 2009 – is now reaching the marketplace, where it will be used in a wide range of coatings and plastics.
The commercial development has solved a quest that began thousands of years ago, and captured the imagination of ancient Egyptians, the Han dynasty in China, Mayan cultures and others – to develop a near-perfect blue pigment.
But now it has happened, in a process that has been described as accidental. OSU chemist Mas Subramanian and his team were experimenting with new materials that could be used in electronics applications and they mixed manganese oxide – which is black in colour – with other chemicals and heated them in a furnace to nearly 2 000 degrees Fahrenheit.
One of their samples turned out to be a vivid blue. Oregon State graduate student Andrew Smith initially made these samples to study their electrical properties.
“It was serendipity, actually; a happy, accidental discovery,” Subramanian says.
The new pigment is formed by a unique crystal structure that allows the manganese ions to absorb red and green wavelengths of light, while only reflecting blue. The vibrant blue is so durable, and its compounds are so stable – even in oil and water – that the color does not fade.
These characteristics make the new pigment versatile for a variety of commercial products. Used in paints, for example, they can help keep buildings cool by reflecting infrared light. Better yet, Subramanian says, none of the pigment’s ingredients are toxic.
OSU has reached an exclusive licensing agreement for the pigment, which is known as “YInMn” blue, with The Shepherd Color Company. It will be used in a wide range of coatings and plastics.
“This new blue pigment is a sign that there are new pigments to be discovered in the inorganic pigments family,” says Geoffrey Peake, research and development manager for The Shepherd Color Company. Commercial quantities of the pigment will be available later this year, he adds.
The lack of toxic materials is critical, Subramanian points out, and a hallmark of the new pigment.
“The basic crystal structure we’re using for these pigments was known before, but no one had ever considered using it for any commercial purpose, including pigments,” Subramanian says. “Ever since the early Egyptians developed some of the first blue pigments, the pigment industry has been struggling to address problems with safety, toxicity and durability.”
Another commercial use of the product – in addition to coatings and plastics, may be in roofing materials. The new pigment is a “cool blue” compound that has infrared reflectivity of about 4% – much high than other blue pigments – and could be used in the blue roofing movement.
“The more we discover about the pigment, the more interesting it gets,” says Subramanian, who is the Milton Harris Professor of Materials Science in the OSU College of Science. “We already knew it had advantages of being more durable, safe and fairly easy to produce. Now it also appears to be a new candidate for energy efficiency.”
In addition to testing the blue pigment for other applications, Subramanian is attempting to discover new pigments by creating intentional laboratory “accidents”. “Who knows what we may find,” he says.
His original work was funded by the National Science Foundation.