Preparation and Nonlinear Optical Property of Polydiacetylenes from Dialkyltetraacetylene Compounds

Abstract To obtain polydiacetylenes with π-conjugation between polymer backbone and side chains, diacetylene monomers with acetylenic substituents, i.e., dialkyltetraacetylene compounds, were synthesized. It has been found that they were highly polymerizable on UV or γ-ray irradiation and became deeply blue-colored polymers. It was confirmed that the polymerization proceed topochemically via 1,4-addition to give polydiacetylenes with acetylenic substituents. Third order nonlinear optical susceptibility of these polymers, evaluated from third harmonic generation by Maker fringe method, were larger than that of the corresponding dialkyldiacetylene polymer.