The star-like molecule, 2, 7-diamino-9,9-bis(4-aminophenyl)fluorene, was used to effectively control the orientation of linear polyimide chains so as to prepare star-like polyimide systems that are excellent candidates of improved compressive properties compared to the linear analogues. The synthesis of the central fluorene unit involved the reaction of 2,7-dinitro-9-fluorenone with aniline in the presence of aniline hydrochloride followed by the reduction of the nitro functionalities. The incorporation of this favorable geometric molecule by condensation with the C-terminus of the linear polyimides resulted in the synthesis of three-dimensional polyimides. Polyimide systems exhibiting improved solubility in organic solvents and strong acids, and transitions at lower temperatures were prepared by introducing hexafluoro groups (bis-4,4’-aminophenylhexafluoropropane and 4,4’-(hexafluoroisopropylidene)diphthalic anhydride), and by using a dianhydride (bicyclo[2.2.2]oct-7-ene-2,3,5,6-tetracarboxylic dianhydride) with reduced symmetry and decreased π-electron density relative to benzene tetracarboxylic dianhydride. An improvement in the solubility of the thermally stable three-dimensional polyimides was observed as a result of a decrease in linearity and an increase in free volume due to the star-like structure of the three-dimensional polyimides.
| Identifer | oai:union.ndltd.org:auctr.edu/oai:digitalcommons.auctr.edu:dissertations-4488 |
| Date | 01 December 1996 |
| Creators | Petzold, Odessa N. |
| Publisher | DigitalCommons@Robert W. Woodruff Library, Atlanta University Center |
| Source Sets | Atlanta University Center |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | ETD Collection for AUC Robert W. Woodruff Library |
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