Synthesis and liquid‐crystal‐aligning properties of novel aromatic poly(amide imide)s bearing n‐alkyloxy side chains |
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| Authors: | Anjana Sarkar Arvind S More Prakash P Wadgaonkar Gyo Jic Shin Jin Chul Jung |
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| Affiliation: | 1. Polymer Science and Engineering Division, National Chemical Laboratory, Pune 411008, India;2. Polymer Research Institute/Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH), San 31, Hyoja‐dong, Pohang 790‐784, Korea |
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| Abstract: | Novel aromatic poly(amide imide)s (m‐PAIs, m = 8, 12, 16) containing preformed isophthalamide unit and pendent n‐alkyloxy (‐O‐n‐CmH2m+1, m = 8, 12, 16) side chains were prepared in thin films by polymerization of pyromellitic dianhydride (PMDA) with N,N′‐bis(4‐aminophenyl)‐5‐(n‐alkyloxy)isophthalamides (m‐DAs) obtained from N,N′‐bis(4‐nitrophenyl)‐5‐(n‐alkyloxy)isophthalamides (m‐DNs). The m‐PAI films were tough, flexible and transparent with inherent viscosities in the 1.25–1.67 dL/g range in DMAc and soluble in DMAc and NMP on heating. In TGA m‐PAIs began to degrade around 440°C and in DSC no phase transitions were detected. In X‐ray diffractometry the m‐PAIs appeared amorphous with loosely developed layered crystalline structure. In liquid crystal (LC)‐aligning performance measured using 4‐n‐pentyl‐4′‐cyanobiphenyl (5CB) on thin film surfaces rubbed with standard velvet fibers, the m‐PAIs showed homogeneous LC alignment parallel to the rubbing direction with 2.5–17.5° pretilt angles, depending on the rubbing density and n‐alkyloxy side chain length. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007 |
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| Keywords: | poly(amide imide)s aromatic di(amide amine)s n‐alkyloxy side chains liquid crystal alignment Pretilt angle |
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