A new series of diacetylenes, 9-(arylamino)-5,7-nonadiynyl-N-(alkoxycarbonylmethyl)urethanes was synthesized based on three design paradigms: (1) the polydiacetylene (PDA) conjugated backbone, (2) one side group as a chromophore, and (3) the remaining side group with components to promote solubility and processability. After exposure to 60Co γ-radiation, the resulting polydiacetylenes were highly soluble in many common organic solvents. These diacetylene monomers can be functionalized with ease not only before but after polymerization as well. Tricyanovinylation of diacetylene monomers followed by polymerization gave insoluble polymers, possibly due to strong interactions involving tricyanovinyl groups. However, tricyanovinylation after polymerization gave polymers soluble in common organic solvents with 45−55% degree of functionalization. The diazonium coupling reaction could also be carried out at the phenyl ring of the diacetylene monomer both before and after polymerization. In contrast to the intrac...