Synthesis and characterization of an aromatic diamine and its polyimides containing asymmetric large side groups
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Synthesis and characterization of an aromatic diamine and its polyimides containing asymmetric large side groups Chenyi Wang1 · Bin Yu1 · Cairong Jiang1 · Xiaoyan Zhao1 · Jian Li1 · Qiang Ren1 Received: 20 August 2019 / Revised: 14 November 2019 / Accepted: 19 December 2019 © Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract A novel aromatic diamine monomer with asymmetric large side group: 4-(2,4,6-trimethyl)phenoxy-1,3-diaminobenzene, was synthesized by a two-step organic reaction. The monomer was separately subjected to a one-step high-temperature polycondensation reaction with three commercial aromatic dianhydrides to obtain a series of polyimides. Their structures and properties were characterized and studied by FTIR, NMR, UV, TGA, DSC, etc. The obtained polyimides showed excellent solubility not only in high-boiling solvents such as NMP, DMAc, and DMF, but also in low-boiling solvents such as C HCl3 and C H2Cl2. Their tensile strength was in the range of 76.9–93.5 MPa, the elongation at break was between 4.8% and 7.3%, and the modulus of elasticity was in the range of 1.6–1.8 GPa. The obtained films exhibited good optical transparency, and the representative polyimide derived from 4,4′-oxydiphthalic dianhydride exhibited a light transmittance of more than 83% at a wavelength of 450 nm. Moreover, these polyimides also possessed good thermal properties. Their glass transition temperatures are between 285 °C and 345 °C, and the 10% weight loss temperature in air and nitrogen is above 463 °C, showing excellent thermal properties. Keywords Polyimides · Large side group · Solubility
Introduction Aromatic polyimides were a class of important heterocyclic polymers with imide ring structure in the main chain. They possessed excellent thermal stability, mechanical properties, electrical properties, chemical resistance and low thermal expansion, and * Chenyi Wang [email protected] * Xiaoyan Zhao [email protected] 1
Jiangsu Key Laboratory of Environmentally Friendly Polymeric Materials, School of Materials Science and Engineering, Changzhou University, Changzhou 213164, Jiangsu, China
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could be used as special engineering plastics, separation membrane materials, and high-temperature-resistant coatings in aerospace, petrochemical, microelectronics, gas separation and other fields [1–4]. However, for most aromatic polyimides, due to the rigid benzoimide rings in the main chain and the structural regularity, they showed poor solubility and were difficult to directly form membrane. In addition, such polyimides also had deeper colors and poor optical transparency, which limited their application in the field of optoelectronics to a certain extent [5–10]. Therefore, the design and development of polyimides with good film formation and high optical transparency had important research significance and practical application value. At present, it was found that the solubility and film formability for polyimides could be improved by reasonably designing
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