On the weekend I did something I had not done for about 16 years. I went to the supermarket and bought a packet of disposable nappies (diapers). Why? It was all for science outreach!
This week I am doing a few demos at a kids club run by our church. Last year I did mentos and coke rockets. My glamorous assistant, my darling wife, found this video, which inspired us to increase our repertoire.
The key material is sodium polyacrylate which is a superabsorbent polymer. It is amazing that they can increase their volume by a factor of as much as 500. This is a phase transition analogous to a liquid-gas transition.
A nice follow up is to add salt which destroys the cross-linking and reduces the polymers ability to absorb water.
This is shown in the video below.
A nice mean-field theory of the salt induced volume-collapse is given in this PRL from 1980.
Subscribe to:
Post Comments (Atom)
Quantum states of matter and metrology
Two characteristics of states of matter are associated with them being referred to as quantum. One characteristic is the importance of quant...
-
Is it something to do with breakdown of the Born-Oppenheimer approximation? In molecular spectroscopy you occasionally hear this term thro... -
If you look on the arXiv and in Nature journals there is a continuing stream of people claiming to observe superconductivity in some new mat...
-
I welcome discussion on this point. I don't think it is as sensitive or as important a topic as the author order on papers. With rega...
No comments:
Post a Comment