Nerval's Lobster writes "From the annals of Really Important Science comes word that a research assistant who picked up his B.S. just seven months ago has invented a coffee mug designed to keep java at just the right piping-hot temperature for hours. Logan Maxwell, who got his undergraduate degree in chemical engineering from North Carolina State University in May, created the "Temperfect" mug as part of his senior design project for the College of Engineering. Most insulated mugs have two walls separated by a soft vacuum that insulates the temperature of a liquid inside from the temperature of the air outside. Maxwell's design has a third layer of insulation in a third wall wrapped around the inner basin of the mug. Inside is a chemical insulator that is solid at room temperature but melts into a liquid at 140 degrees Fahrenheit. The insulator – which Maxwell won't identify but swears is non-toxic – turns to liquid as it absorbs the extra heat of coffee poured into the mug at temperatures higher than 140 F, cooling it to a drinkable temperature quickly. As the heat of the coffee escapes, the insulating material releases heat through the inner wall of the mug to keep it hot as long as possible; a graph mapping the performance of a prototype shows it could keep a cup of coffee at between 128 F and 145 F for as long as 90 minutes. "Phase-change" coffee-mug insulation was patented during the 1960s, but has never been marketed because they are difficult and expensive to manufacture compared to simpler forms of insulation. While working on the Temperfect design, Maxwell met Belgian-born industrial designer Dean Verhoeven, president of consulting form Ancona Research, Inc., who had been working on a similar design and had already worked out how to manufacture a three-walled insulated mug cost effectively. The two co-founded a company called Joevo to manufacture the mugs."
According to the Joevo Kickstarter page
, you can get one starting at $40. For that much, I'd like a clever lid like this Contigo has