ZhengHua Yang

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Name: 杨正华; Yang, ZhengHua
Organization: The Changchun Institute of Applied Chemistry , China
Department:
Title: (PhD)

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Co-reporter:Zuolin Wu, Baochun Han, Chunhua Zhang, Danyang Zhu, Lianxun Gao, Mengxian Ding, Zhenghua Yang
Polymer 2012 Volume 53(Issue 25) pp:5706-5716
Publication Date(Web):30 November 2012
DOI:10.1016/j.polymer.2012.10.024
A new optically active spirobifluorene-based diamine monomer, (R)-2,2′-bis(4-amino-2-trifluorom-ethylphenoxy)-9,9′-spirobifluorene, was synthesized using (R)-2,2′-dihydroxy-9,9′-spirobifluorene as starting material. The absolute stereochemistry of the chiral diamine was determined by single crystal X-ray diffraction. A series of novel chiral polyimides were prepared from the diamine with various aromatic dianhydrides via a two-stage process with chemical imidization method. All these optically active polyimides were readily soluble in many organic solvents and could afford flexible, tough and transparent films with an UV–vis absorption cutoff wavelength at 351–375 nm. The glass transition temperatures of these polyimides were recorded between 262 and 281 °C by differential scanning calorimetry, and the 5% weight loss occurred at temperatures above 510 °C. The specific rotations of these chiral polyimides ranged from −48.5° to +73.0° depending on the structures of the aromatic dianhydrides. All the optically active polyimides exhibited high chiral stability in solid state or in DMAc solvent at high temperature due to introduction of chiral spirobifluorone group into polymer backbones. The circular dichroism (CD) spectroscopic properties of these chiral polyimides in tetrahydrofuran solutions were also studied.
Co-reporter:Zuolin Wu;Yanjiong Huang;Chunhua Zhang;Danyang Zhu;Zheng Bian;Mengxian Ding;Lianxun Gao
Journal of Applied Polymer Science 2010 Volume 117( Issue 6) pp:
Publication Date(Web):
DOI:10.1002/app.32264

Abstract

A series of optically active polyamides containing di-O-methyl-L-tartaryl moieties in the main chain were synthesized by polycondensation of di-O-methyl-L-tartaryl chloride 5 with diamines and characterized by gel permeation chromatography, UV–vis, circular dichroism (CD), IR, and NMR spectroscopies. The polycondensation reaction could be carried out under mild conditions and the reaction time was short (2–3 h). The key monomer 5 prepared from L-tartaric acid via esterification, etherification, hydrolysis, and chlorination was easily purified by vacuum sublimation. These polyamides with number average molecular weights ranging from 14,000 to 35,000, displayed large optical activity in dimethyl sulfoxide solution, and their specific optical rotations oscillated between 87.2° and 210.7° depending on the structures of the diamines. The glass transition temperatures of these polyamides were in the range of 106–191°C, and the 10% mass loss occurred at temperature above 300°C. The polyamides derived from aromatic diamines exhibited higher Tg and thermal stability than those derived from aliphatic diamines. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010