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Synthesis and photo-induced solution properties of new rigid-rod polyimides |
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| Authors: | Masao Tomikawa Frank W Harris Stephen Z D Cheng Edward Galentier |
| Affiliation: | a Electronic and Imaging Materials Research Laboratories, Toray Industries Otsu, Shiga 520, Japan b Institute of Polymer Science, The University of Akron, Akron, OH 44325-3909, USA c Department of Physics, Kent State University, Kent, OH 44242, USA |
| Abstract: | A series of new, substituted pyromellitic dianhydrides were synthesized from 1,2,4,5-tetramethylbenzene. New soluble rigid-rod polyimides were obtained from the dianhydrides and 2,2′-bis(trifluoromethyl)-4,4′-biphenyl (PFMB) in phenolic solvents in the presence of isoquinoline as a catalyst. The polyimides are soluble in N-methyl-2-pyrrolidone (NMP), N,N-dimethylacetamide (DMAc), m-cresol and other solvents, in spite of having no bending in their rigid structures. UV irradiation changed color of the polyimide solutions and also their viscosity. We observed new absorbance in the 700-nm region and an ESR signal by UV irradiation. The new visible absorbance and the ESR signal are derived from the same origin. They are attributed to the anion radical of the diimide moiety in the polyimide as deduced from the hyper fine structure of the ESR signal. In addition, UV irradiation diminishes the solution viscosity. |
| Keywords: | Rigid-rod polyimide Visible spectra Electronic spin resonance spectrometry Viscosity Anion radical |
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