Synthesis of Diacetylene-Substituted Polydiacetylenes with Alkoxycarbonylurethane Substtuents and Their Optical Properties

Abstract Octatetrayne monomers with urethane groups, i.e. R-C≡C-C≡C-C≡C-C≡C-R in which R˭‒(CH2)m-OCONH-CH2-COO-(CH2)n-H (5ECMU-4A: m=5, n=2; 3BCMU-4A: m=3, n=4), were synthesized, and their polymerization behavior and optical properties were investigated. The polymer structures were confirmed to be diacetylene-substituted polydiacetylenes like polymers from octatetraynes studied previously. Though both of thin film polymers obtained by γ-ray and UV irradiation showed excitonic absorption around 680 nm, absorbance of γ-ray irradiated one was three times larger than that of UV-irradiated one. Thus, it was found that UV-irradiation caused not only polymerization but also deterioration of the produced polymers, and γ-ray irradiation is superior to UV irradiation for polymerization. The third-order nonlinear optical susceptibilities (χ(3)(-3ω) s) of these polymers were (0.56–3.7)×10−11 esu, and roughly proportional relation between χ(3) s in three-photon resonant region and absorbance were found in this series...