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Telechelics by Polymer Chain Scission Reactions
Published in Eric J. Goethals, Telechelic Polymers: Synthesis and Applications, 2018
Ditelechelics of PVC-bearing peroxide functions are not prone to copolycondensation at temperatures equal or higher than 100°C due to poor thermal stability, but can be transformed into diacylchloride ditelechelics that allow the preparation of block copolycondensates.9 The chlorinating agent of choice is phosphorus pentachloride, since thionyl chloride induces a partial degradation of the polymeric substrate. This modification of the terminal functions can be done without significant change of the molecular weight. The diacylchloride telechelic can in turn be transformed into a dihydroxytelechelic by reaction with hydroxylamine.9 This compound can be used for further classical polycondensation. However, it is worth recalling here that the presence of peroxidized side groups due to the above synthesis greatly increases, after their reduction, the final functionality expressed as the number of hydroxylic functions per molecule. As a consequence, gelation instead of chain extension can be observed.
Self-assembling behaviour of new functional photosensitive cinnamoyl-based reactive mesogens
Published in Liquid Crystals, 2020
Alexej Bubnov, Martin Cigl, Nela Sedláčková, Damian Pociecha, Zuzana Böhmová, Věra Hamplová
4-hydroxybezoic acid (27.60 g, 0.20 mol) was dissolved in a mixture of sodium hydroxide (20.0 g, 0.50 mol) and water (300 ml) and cooled to 0°C. Then, methyl chloroformate (28.30 g, 0.30 mol) was added dropwise with stirring, keeping the temperature at 0°C. The reaction mixture was then stirred for ca. 2 h while a white precipitate was gradually formed. Resulting mixture was acidified by a small amount of hydrochloric acid (pH 4–5) and white solid was filtered off and washed with cold water. After drying, the solid was recrystallised from ethanol and dried under vacuum. Obtained 4-(methoxycarbonyloxy)benzoic acid was suspended in thionyl chloride (40 ml) and a catalytic amount of DMF was added. The reaction mixture was refluxed for 2 h. The excess of thionyl chloride was distilled off. Oily residue was diluted with toluene and the solvent removed on rotatory evaporator. Obtained benzoyl chloride 11 was used in the next synthetic step without further purification. 1H NMR (CDCl3): 8.18 (2H, d, J = 8.8, H-2, H-6), 7.37 (2H, d, J = 8.8, H-3, H-5), 3.96, (3H, s, OCH3).
Electric field assisted-unidirectional hybrid films of carbon nanotubes and liquid crystal polymer for light modulation
Published in Liquid Crystals, 2020
Weiwei Tie, Surjya Sarathi Bhattacharyya, Zhi Zheng, Kyung Jun Cho, Tae Hyung Kim, Young Jin Lim, Seung Hee Lee
Carboxylic CNTs were further modified to make them more compatible with the reactive mesogeon monomer mixture. A mixture of the abovementioned carboxylic CNTs (0.2 g) and thionyl chloride (80 ml) was refluxed for 24 h and then excess thionyl chloride was evaporated at reduced pressure. Next, the above-mentioned CNTs were carefully dried in vacuo, flushed with argon, and then treated with a mixture of dry pyridine (1 ml) and DMAP (3 mg) in dry dichloromethane (25 ml). After refluxing for 24 h, the mixture was filtered through PTFE filters and washed with water and chloroform. Finally, the product was dried in a vacuum oven at 60ºC to yield mesogenic CNTs (m-CNTs). Scanning electron microscopy images of the m-CNTs are shown in Fig. S1.
Main‐chain liquid‐crystalline polymers bearing different anion
Published in Liquid Crystals, 2023
Lu Bai, Jungang Zhang, Yi Teng, Zilu Gao, Jiwei Wang, Fanbao Meng
D-camphoric acid (20.02 g, 0.10 mol) and thionyl chloride (32.85 ml, 0.45 mol) were successively added to a three-neck flask containing an alcohol thermometer, a spherical condensing tube, and an agitator. Then 2 mL N, N-dimethylformamide was added as the catalyst. The mixed solution was stirred thoroughly at room temperature for an hour and then heated to 60 ℃ for 8 hours. Then, the temperature was raised to 80 ℃ for vacuum distillation to remove excess thionyl chloride, and finally, white liquid acyl chloride was obtained. The synthesis route is shown in Figure 1(a). Fourier transform infrared (FTIR) spectrum (KBr, cm−1): 2925, 2852 (C-H), 1786 (C=O).