PIDA, or poly(diiododiacetylene), is an organic polymer that has a polydiacetylene backbone. It is one of the simplest polydiacetylenes that has been synthesized, having only iodine atoms as side chains. It is created by 1,4 topochemical polymerization of diiodobutadiyne. It has many implications in the field of polymer chemistry as it can be viewed as a precursor to other polydiacetylenes by replacing iodine atoms with other side chains using organic synthesis, or as an iodinated form of the carbon allotrope carbyne.