April 2, 2007 1 Comment
…is what I came across during tonight’s post-midnightly journey through the wild wild web. When searching for the keyword polymer in YouTube, I found a short animation about polymer reptation. I had to chuckle, because I had seen this movie before when someone taught me about the reptation model in a very elegant and wonderfully entertaining way.
The reptation model was developed by de Gennes and explains some of the behaviour of high molecular weight polymers in the melt. Consider a polymer chain, surrounded by other chains. Now the movements of such a polymer chain are constrained by the presence of other chains surrounding it and therefore the chain is only free to move within what is essentially a topological tube. Within that tube, it can carry out snake like motions (hence reptation) and only advance by diffusing it’s stored lengths.
de Gennes, by the way, is a polymath. A physicist by training, he made substantive contributions to such diverse areas as magnetism, liquid crystals, superconductivity and polymer physics. Though he formally retired in 2002, at the moment he is working on the comprehension of living systems and cellular mechanisms. Go and look him up, he is a fascinating character.