Nam, Ki-Ho Kim, Hyeonil Choi, Hoi Kil Yeo, Hyeonuk Goh, Munju Yu, Jaesang Hahn, Jae Ryang Han, Haksoo Ku, Bon-Cheol You, Nam-Ho 2024-01-20T02:31:36Z 2024-01-20T02:31:36Z 2021-09-05 2017-01-13 0032-3861 https://pubs.kist.re.kr/handle/201004/123205 New diamines for high-performance poly(ester imide)s (PEsIs) containing dimethyl groups at the ortho-position of amino groups and ester derivatives have been developed to improve optical transparency and glass transition temperature (T-g) while maintaining a low coefficient of thermal expansion (CTE). Four kinds of PEsIs derived from bis(4-amino-3,5-dimethylphenyl) terephthalate (BADMT) and aromatic dianhydrides such as 1,2,4,5-benzenetetracarboxylic dianhydride (PMDA), 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA), 4,4'-oxydiphthalic anhydride (ODPA), and 4,4'-(hexafluoroisopropylidene)diphthalic (6FDA) were synthesized via a two-step polycondensation. All PEsIs exhibited outstanding properties, such as light color, a good transmittance of >90% at 550 nm, high Tg above 289 degrees C and 5% weight loss temperature (483-511 degrees C), and low CTE (11-68 ppm/degrees C). The effect of the substituent on molecular packing and properties, including optical and thermomechanical properties for the resulting PEsIs were examined in detail. The temperature-dependent CTE of the PEsIs was determined using molecular dynamics (MD) simulation. The molecular orbital (MO) calculation models support the discussions on the electronic substituent effect of the PEsl main chains. Our molecular architecture and systematic property studies with MD and MO promote a better understanding of the polyimides. (C) 2016 Elsevier Ltd. All rights reserved. English ELSEVIER SCI LTD HIGH REFRACTIVE-INDEX AROMATIC POLYIMIDES SOLUBLE POLYIMIDES HIGHLY TRANSPARENT FILMS IMIDE)S GAS Thermomechanical and optical properties of molecularly controlled polyimides derived from ester derivatives Article 10.1016/j.polymer.2016.11.062 1 POLYMER, v.108, pp.502 - 512 POLYMER 108 502 512 scie scopus 000392356900054 2-s2.0-85006792224 Polymer Science Polymer Science Article HIGH REFRACTIVE-INDEX AROMATIC POLYIMIDES SOLUBLE POLYIMIDES HIGHLY TRANSPARENT FILMS IMIDE)S GAS Poly(ester imide) Optical transparency Thermomechanical stability Molecular orbital Molecular dynamics