Synthesis of Diacetylene-Substituted Polydiacetylenes with Alkoxycarbonylurethane Substituents and their Optical Properties

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 y-ray and UV irradiation showed excitonic absorption around 680 nm, absorbance of y-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 y-ray irradiation is superior to UV irradiation for polymerization. The third-order nonlinear optical susceptibilities (x(3)(-3ω) s) of these polymers were (0.56-3.7)x10-11 esu, and roughly proportional relation between x(3) s in three-photon resonant region and absorbance were found in this series of polymers.