Forming Nanostructures with EntropyCategory: Science & Technology
Posted: August 1, 2012 01:41PM
Though it has been several years at this point, I can still remember the lesson on entropy in my high school chemistry class. Entropy, often associated with disorder and lost energy, is an important thing when trying to determine if some event will occur because, by the laws of thermodynamics, entropy must never decrease when something to happens. An example of energy lost as entropy would be the movement of the air particles displaced as I type this on my keyboard. The particles take that energy and bounce off each other in a chaotic pattern and it will never be possible to harvest all of that energy again.
Despite this tendency towards an increase of chaos though, researchers at the University of Michigan have found a way to actually use entropy to create well-ordered structures. The researchers were studying the behaviors of different nanoparticle shapes and discovered that he chaotic motion of these particles can be used to fit them together into a crystal-like structure. The key is to squeeze the particles together essentially. Throw enough dice into a rectangular box and start shaking it. Eventually the shaking will cause the dice to align their faces and form an ordered structure, despite the chaotic motion from the shaking.
Like those dice though, these particles do not bond with each other. If they did the entropy of the system would have to decrease, which the laws of thermodynamics forbid. This spontaneous structure formation is still useful though, as it allows for an efficient way to make nanostructures by controlling the shape of the nanoparticles creating it.