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    Let's see what one of these polymers looks like, next to a chain of good ol' polyethylene for comparison:

    PolyketonesReference of this text is: http://www.gif" /> It's not much different. You make carbon monoxide every time you burn wood, or a candle, or just about anything containing carbon.ws/macrog/images/ket02. This is not to be confused with a carillon, which is a musical instrument with differently pitched bells, which are often controlled with a piano-like keyboard.ws/macrog/images/ket08.pslc.ws/macrog/images/ket05. We've seen high performance before.pslc.pslc.

    Keep watching this page. This comes in handy should you want to make a car part out of this stuff. But that's no problem with polyketones!

This is all very nice, but really, now, what's the big deal? There are lots of high performance plastics out there. The only difference is that the polyketone has those carbonyl groups in it. A polyketone is of course a polymer with a ketone group in the backbone chain. The reaction is also easy to carry out.ws/macrog/images/ket03. This attraction is so strong that while polyethylene melts at a mere 140oC, the polyketone doesn't melt until 255 oC!

There was a problem with this polyketone when Shell first made it. Propylene reacts just like ethylene does, so we end up with a polymer that looks like this:


For polyketones at a glance, click here!

I would just love to tell you that many wonderful things are made of polyketones, but I can't. This makes the polyketones very strong, but the down side is that it also makes them very brittle. These polar carbonyl groups are attracted to each other, and very strongly at that. They won't dissolve in much of anything. What makes polyketones so special?

This is what makes polyketones so special. Ethylene is on the left and carbon monoxide is on the right. Cheap monomers, and easy chemistry make polyketones rather cheap, a whole lot cheaper than other high performance plastics. They can still pack, but not as well as before. But the good part is that the polymer is now a lot tougher and less brittle..

Here's some models of the monomers if you want to play with them.pslc.ws/macrog/images/ket06.ws/macrog/images/ket01. Carbon monoxide is dirt cheap, too.pslc. Shell has just put this family of polymers on the market and sells them under the name Carilon.gif" />

    These polyketones have another interesting property.

    One Last Detail

Every now and then you get an extra methyl group attached to one of the ethylene units. The bad part is that the melting temperature drops to about 220 oC, because the crystals aren't as strong.. But those carbonyls do a lot. To make polyketones, you take ethylene gas and carbon monoxide, and react them with a palladium(II) catalyst:

Ethylene is dirt cheap; it's the monomer for polyethylene. A car part is no good if it dissolves when you spill gasoline on it. The polyketones we're going to talk about on this page are based on the picture you see at the top of the page, where R' is an ethylene linkage, -CH2CH2-. They decided to throw a little bit of propylene in with the ethylene and the carbon monoxide when they make the polymer. This is because oxygen is electronegative and draws electrons away from the carbon atom.ws/macrog/images/ket07.pslc.ws/macrog/images/ket00.

So what's so great about polyketones? Let's find out by taking a look at them. You see, these polymers are very highly crystalline, that is, the polymer chains are packed together in a very orderly fashion.gif" />
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