Polyacetylene
Polyacetylene (PA) is conducting polymer of the rigid-rod polymer host family.
The polymerization of the acetylene (chemical fomula C2H2, structurally: HC≡CH) results in a long chain of carbon atoms with alternating single and double bonds between them, each with one hydrogen atom which could be replaced by a functional group. Schematically (with hydrogen atoms not shown) ...C=C-C=C-C...