The model above is an image of the pdb model you can view
by clicking here or you can just click on the image itself.
Either way, be sure to close the new window that opens up
with the 3D model in it when you are ready to come back here.
Another nifty thing about PVDF is that it's a piezoelectric material. What does that mean? That means that when it's placed in an electric field it changes its shape.
Because fluorine is so much more electronegative than carbon, the fluorine atoms will pull electrons away from the carbon atoms to which they are attached. This means the -CF2- groups in the chain will be very polar, with a partial negative charge on the fluorine atoms and a partial positive charge on the carbon atoms. So when they're placed in an electrical field, they align. This causes the polymer sample to deform, all those -CF2- groups trying to align.
Now here's the fun part:
If you put it in an alternating electrical field, it'll vibrate, deforming in one direction, and then in the opposite direction. This vibration can be used to produce sound. This is how piezoelectric tweeters work.
PVDF is made by free radical vinyl polymerization of the monomer vinylidene fluoride, like this:
Here's what that monomer vinylidene fluoride looks like in 3-D:
Want to see some more halogenated polymers? Check out these:
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