| Content:Part A:The seven different molecular weight of hyperbranched azo polyesters (HBPAZO), prepared by condensation polymerization of the AB2 monomer diethyl5-(4-hydroxyethoxyphenylazo)isophthalate in the presence of either a B3 core (triethyl1,3,5-benzenetricarboxylate), was controlled by varying the core to monomer ratio. The structures of monomer and HBPAZO were confirmed by UV-vis, IR, 1H NMR, 13C NMR. The Degree of Branching (DB) of polymers were calculated by the 13C NMR, The DB is 0.43, 0.50, 0.51, 0.50, 0.48, 0.50 and 0.47, respectively. The DB was increased when the B3 core was added. The molecular weights and their distributions of the polymers were determined by gel permeation chromatography (GPC), The Mw is 14950, 12554, 16708, 15637, 15694, 11471, 15716g/mol and PD is 3.74, 3.13, 3.79, 3.38, 3.64, 2.83, 3.19, respectively. The polymers are soluble in common organic solvents such as chloroform and tetrahydrofuran, and solutions have characteristically low intrinsic viscosities between 1.0924 and 0.1862 dL/g.Tg is between 88.0 and 121.6℃,which determined by DSC. And all polymers are shown as amorphous. The thermal stability of polymers are characterized by DTA- TG, the decomposed temperatures are between 333.8 and 356℃,and all have well thermal stability. Below the radiation of 365nm UV light, both of monomer and polymer show trans-cis photoisomerization, monomer and polymer are photic stability after the irradiation of 8 and 9 minutes, respectively. The content of cis- isomer (cis%) and the rate constant of photoisomerization (Kp ) are calculated, which are 73.5%, 61.3%, 64.3%, 65.0%, 62.2%, 62.2%, 64.0%, 62.8% and 0.5956, 0.5494, 0.5228, 0.5105, 0.48, 0.4894, 0.4704, 0.4709s-1,respectively. The photostationary state time of monomer is less than the polymers, both of the monomer's cis% and Kp are more than the polymer's, and the Kp of HBPAZO-G0 is more than other polymers'. which was attributed to the increased steric hindrance in the hyperbranched polymer. Due to the good solubility and photo absorption property, HBPAZO may be applied in photo-induced holographic gratings, reversible optical storage systems and other optical switch devices.Part B:A new conjugated polymer containing azobenzene and 1 ,3 ,4 -oxadiazole unit(LPOXD) was synthesized by a two step polycondensation reaction with 5-(4-hexadecyloxy phenylazo) isophthaloyl dichloride and p-phthaloyl hydrazide. The structures of LPOXD were confirmed by UV-vis, IR and 1H NMR. The polymer is soluble in common organic solvents such as chloroform and tetrahydrofuran, and the intrinsic viscosity is 0.2860 dL/g. The thermal stability of polymers are characterized by DTA- TG, the decomposed temperature is 338.5℃. The molecular weights and its distribution of the polymer were determined by gel permeation chromatography (GPC), The Mw is 8501g/mol and PD is 1.55, respectively. Below the radiation of 365nm UV light, LPOXD show a trans-cis photoisomerization. The maximal wavelength was blue-shift to 329nm with the increase of cis- isomer. The band gap energy of the polymer was estimated by the optical method (Eg=2.31 eV). The HOMO and LUMO energies of the polymer were estimated to be 5.60 and 2.66 eV by cyclic voltammetric investigation. The electrical conductivity of LPOXD is 3.2×10-1s/m by Four-probe measurement, the LPOXD has property of semiconductor. LPOXD contains azobenzene and long side chain of alkyl, and shows photo absorption property, good solubility and high electron affinity, which can be used in the filed of optics, and as electron-transport and electroluminescent material. |
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