Slashdot Mirror
Smart Rubber Promises Self-Mending Products
An anonymous reader writes "French scientists have developed a new rubber that can heal itself after being cut or broken. If two broken ends of the material are pushed together, and left for an hour, they join to become just as stretchy as before. There is even a video of the supposed creation in action. 'Regular rubber gets its strength from the fact that long chains of polymer molecules are coupled, or "crosslinked," in three different ways: through covalent, ionic, and hydrogen bonding between molecules. Of these three bond types, only the hydrogen bonds can be remade once a material is fractured, although normally there are not enough hydrogen bonds for the rubber to re-couple in this way. The solution devised by Leibler and colleagues is to simply get rid of the ionic and covalent bonds. They developed a transparent, yellowy-brown rubber in which crosslinking is performed only by hydrogen bonds.'"
Yes.
The article mentions that this rubber is weaker than most to begin with for just that reason.
It isn't just the number of bonds but the strength of those bonds.
Engineering is the art of compromise.
My guess would be "lots" since the H bonds don't "wear out". Normal polymers wear out by occasionally having covalent bonds break, which then don't repair.
On the flip side, this probably exhibits "cold flow" -- if you put it under tension, it will slowly and permanently deform. Over short time spans, it will be elastic, over long spans it will deform. For many applications that won't matter, but for some it will make it completely unusable.