- Solubility, thermal and photoluminescence properties of triphenyl imidazole-containing polyimides
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In this paper, three kinds of triphenyl imidazole-containing diamines including 2-phenyl-4,5-bis(4-(4-amino-2-trifluoromethylphenoxy)phenyl)imidazole (PBAI), 2-(4-methylphenyl)-4,5-bis(4-(4-amino-2-trifluoromethyl phenoxy)phenyl)imidazole (MPBAI) and 2-(4-trifluoromethylphenyl)-4,5-bis(4-(4-amino-2-trifluoromethylphenoxy)phenyl)imidazole (TFPBAI) were synthesized. Then, a series of polyimide (PI) films were prepared by the solution polymerization of the three diamines and various dianhydrides, such as 4,4′-(hexafluoroisopropylidene)diphthalic anhydride (6FDA), 1,2,4,5-pyromellitic dianhydride (PMDA) and 1,2,3,4-cyclobutanetetracarboxylic dianhydride (CBDA), followed by thermal imidization. The effects of chemical structures on the solubilities and thermal, optical and electrochemical properties of polyimides were explored. All the polyimides exhibited higher glass transition temperatures around 300 °C and excellent solubilities in common polar solvents. The polyimide films derived from CBDA or 6FDA showed better optical properties with light color and transparent characteristics. The fluorescence test showed that the photoluminescence color of CBDA-based polyimide films is in the blue range in the CIE 1931 spectrum, while the polyimide film based on PMDA and 6FDA presented black or weak yellow light. However, all these polyimides in solution exhibited similar blue luminescence. Electrochemical tests indicated that the HOMO and LUMO values of these films were around ?6.5 and ?3.6 eV, and the energy gap difference was about 3.0 eV. Therefore, the triphenyl imidazole-containing polyimides exhibit comprehensive performance, which will be expected as a new kind of functional material for certain application in the optical and optoelectronics fields.
- Bai, Wu,Hu, Zhizhi,Liu, Zhaobin,Lu, Yunhua,Xiao, Guoyong,Zhao, Hongbin,Zhu, Jianmin
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p. 23802 - 23814
(2021/07/13)
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- Novel para-linked and CF3-substituted poly(amide-ether- imidazole)s: Solubility, optical and thermal properties
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A new photoactive fluorinated diamine, 2-(4-trifluoromethylphenyl)-4,5- bis(4-(4-amino-2-trifluoromethylphenoxy)phenyl)imidazole (TFIA), was synthesized and used for preparation of novel fluorinated poly(amide-ether-imidazole)s (PAEIs) by using direct polycondensation of the diamine with various dicarboxylic acids. The resulting PAEIs were amorphous and had intrinsic viscosity [η] in the range of 0.68-0.80 dL/g. The weight average (M w) and number average (Mn) molecular weights of one of the polymer, measured by GPC, were 18,600 g/mol and 11,500 g/mol, respectively. These polymers were readily soluble in a variety of organic solvents and formed low-colored and flexible thin films via solution casting. Their values of cut-off wavelength (λ0) were in the range of 380-390 nm, and all PAEIs films exhibited high optical transparency. According to thermal analysis, these polymers exhibited glass transition temperatures (T g)s in the range of 160-250°C, initial decomposition temperature (Ti) from 295 to 400°C and temperature of 10% weight loss (T 10%) from 400 to 490°C in N2. These polymers exhibited strong UV-vis absorption at 310 nm in solution and in films and their fluorescence emission peaks appeared around 430-520 nm with the quantum yields in solution varied from 10% to 29%.
- Ghaemy, Mousa,Berenjestanaki, Farshad Rahimi
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