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.'"

Comments

Odd

[geek]

Wouldn't removing the other two types of bonds make it naturally more likely to break to begin with? My chem background isnt great, maybe someone could break it down for me.

Re:Odd

[quanminoan]

From TFA:

The downside is that getting rid of covalent and ionic bonding means the material is weaker than regular rubber.

Regular polymers can be made very strong from covalent bonds (polycarbonates, polysulfones). Making a very strong polymer requires quite a lot of covalent bonds, and creates a very strong material that lacks tensile strength. The problem with almost all polymers in engineering applications is two things: creep and degradation. The "creep" part is when the polymer chains, loaded with some force, start to slip and rearrange themselves. This has to be taken into account in many applications, unless you're designing commodity applications such as trash bags, etc. The degradation problem is also largely unavoidable and occurs when these bonds are broken, whether it be from radiation (sunlight, UV, etc.), chemical attack (acids, ozone..). This material lacks these susceptible bonds creating a material that is much weaker, but also much more reliable in the long run. TFA states some potential applications:

The material could eventually make it a cinch to repair holes in shoes, snapped fan belts and punctured kitchen gloves. It might also make strange new products possible - for instance bags that can be ripped open and then resealed. "You don't need a zip when you can make a resealable hole in it," Leibler says.

I'm skeptical, yet hopeful...

[Will the Chill]

because if you watch the video they double the speed of the post-healing stretch, and it's still _really_ slow. With only the video to go on, it seems like this could just as easily be some silly putty or elmers glue + liquid starch.

Of course, if it's true that you can create self-healing rubber by removing the ionic and covalent bonds, leaving only the hydrogen bonds, my next question is obvious:

How many times can this material "heal" itself before suffering internal structure deficiencies?

If it could mend itself an infinite number of times and retain perfect structural integrity, that would truly be a modern miracle of science with untold practical applications.

Can you say self-mending tires, shoe soles, etc?

-WtC

*sig inserted by hand to frustrate sig purists*

Funny...

[raving griff]

...because recently, for a school project, I needed to find some print sources of chemistry in the news. All I had on-hand was an issue of Popular Science, and it had an article on this invention. The catch? The issue was from 2001.

Roads

[ewg]

Please tell me there's some way to incorporate this material into roadways that don't develop potholes. I'm tired of paying for them--in wear and tear on my car and in taxes.

Tires

[Jon Abbott]

Finally, we will all have tires that are invincible! This will be especially useful for road bike tires, which get sliced up rather easily compared to automobile tires...

I want an engineering sample.

[iansmith]

You would need to put some sort of skin over this to keep it from self-reparing in ways it wasn't meant to. If you accidently fold a sheet of this stuff it would adhere to itself. And you though trying to work with plastic wrap without getting it all stuck together was hard.

I bet it would be fun to sculpt with. Cut bits off, stick them back in in other places.. would be a really strange medium to work in.

Or the ultimate version of those pads to stick your cell phone to your dashboard. Except now it will NEVER come off until you slice it off with a razor.

What happens when it gets wet?

[Guppy]

I'm curious if the material material still works in wet or humid conditions. Since water forms a strong hydrogen bond, I'm wondering if having H2O present in the interface of two pieces will "cap" the polymer's bonds and slow or disrupt the self-repair.

In addition, I'm also wondering how permeable the material is to water or water vapor, and if there is any swelling when exposed.