Exotic Materials were materials that were out of this world. They had never been seen on Earth or anywhere before.
(Note: The background section of this page uses most of the same words as Terra Futura's page on metastable allotropes to save time.)
For a long time, it was thought that there were only 92 elements on the periodic table. But in the 1940s, a scientist named Glenn Seaborg discovered neptunium and plutonium while working for the Manhattan Project. Overtime, he extended the Periodic Table to 106 elements. The last of these was Seaborgium, named after the scientist himself. In the 1970s and beyond, the periodic table was extended even further by Seaborg's student Ken Moody. New elements would continue to be discovered for years. But they were all unstable for a time. With the advent of picotechnology, however, the island of stability which Ken Moody predicted in the 1970s was found. The Island of Stability was a revolution. Transuranic elements became useful for the first time. Especially elements 114-126. Because the isotopes were stable, they could be used. This made them useful for reactors, medicine, fuel, etc. Creating more stable isotopes of heavy elements was possible, but picotechnology also allowed for metastable allotropes to be created. Metastable Allotropes started being created in the laboratory in the late 21st century. This was only possible with picotechnology. These new forms of atoms were useful. The most notable was fuel. Metastable fuels had the power of a nuclear rocket. Some space programs used metastable fuels instead of nuclear propulsion because of that. Metastable elements could be used for anything. However, with the advent of femtotechnology, even more exotic materials became possible.
Tech Level: 13-15
With femtotechnology, materials became more exotic. Metals were being produced with very high tensile strength and very high toughness. These were useful in exploring hostile environments like the Sun and the Earth's core. Eventually, this helped bring about faster-than-light space travel. There were other more exotic materials, too. These included metals that were entirely transparent, metals that were luminous, surfaces that were frictionless, and even structures that were ultradense but lightweight. New materials were being made every day as far as anyone knew.