Subject: Double bonds in carbon

Yesterday I asked a teacher at my school (not mine, but teacher) about a 
polymer that would look like ~C=C=C=C~, because I thougt that such stuff 
would be made pretty strong by the double bonds, compared to polyethylene. 
(I have a book that says that molecules are easier to split than to move 
away from other molecules in polymers, because of their [molecules'] high 
mass.) Well, he said that such stuff can't be, because you can't have more 
than a pair of carbons linked by double bonds. I can't see why that would 
be the case. Is it true? If yes, why? If no, does such a polymer exist? 
What's it called, and what's it like?

Re: Double bonds in carbon