Transparent polyamide-imide films with high Tg and low coefficient of thermal expansion: Design and synthesis. (7th October 2020)

• Record Type: Journal Article
• Authors: Lao, Haoji; Mushtaq, Nafeesa; Chen, Guofei; Jiang, Hongyu; Jiao, Yang; Zhang, Anjiang; Fang, Xingzhong
• Is Part Of: Polymer. Volume 206(2020)
• Publication Date: 2020-10-07
• Subjects: Polyamide-imides -- Coefficient of thermal expansion -- Transparency; Polymers -- Periodicals; Polymerization -- Periodicals; Polymères -- Périodiques; Polymérisation -- Périodiques; 547.7
• DOI: 10.1016/j.polymer.2020.122889
• Languages: English
• ISSNs: 0032-3861

Abstract

Abstract: Two series of optically transparent polyamide-imides (PAIs) were prepared by copolymerization of trimelletic acid chloride (TMAc), p -phthaloyl chloride (TPC), 2, 2′-bis(trifluoromethyl)-[1, 1′-biphenyl]-4, 4′-diamine (TFDB) and 4, 4'-(9-fluorenylidene) diamine (FDA). These series of PAIs displayed high glass transition temperatures ( T g s) ranging from 340 to 441 °C, 5% weight loss temperatures ( T 5% s) in nitrogen with 459–505 °C, and low coefficient of thermal expansion (CTE) of 21–56 ppm/K, which greatly affected by the feed ratio of rigid TPC units and cardo diamine in the polymer main chain. The transmittances at 500 nm (T500nm ) of the PAI films were found in the range of 70.0–87.7%, All polymers demonstrated good organosolubility and mechanical properties with tensile strengths of 77–146 MPa, tensile moduli of 2.9–5.8 GPa and elongations at break of 2.9–8.2%. PAI-7-8 presented the best combination of high T g of 401 °C and high tensile modulus of 5.0 GPa, low CTE value of 24 ppm/K, and high transparency (T500nm ) of 87.2%. Graphical abstract: Image 1 Highlights: Two series of PAIs were synthesized for transparent films with high T g and low CTE. The effect of FDA and TPC monomer ratios on the properties was investigated. PAI-7-8 showed excellent properties with high T g, transparency, modulus, and low CTE.