| Phenylindane monomers 5(6)-amino-1-(4-aminophenyl)-1,3,3-trimethylindane (DAPI), 5,6-diamino-1-(4-aminophenyl)-1,3,3-trimethylindane (TAPI) and 6-hydroxy-1-(4-hydroxyphenyl)-1,3,3-trimethylindane (DHPI) were synthesized and characterized. DAPI, as well as other diamines, were then utilized in solution step polycondensation with a number of commercially available dianhydrides using either the two-step ester-acid solution imidization or the high temperature solution imidization routes. High molecular weight soluble fully cyclized polyimides were successfully synthesized using a 1:1 molar ratio of dianhydride to diamine. The polyimides were film forming and were characterized by size exclusion chromatography (SEC), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and selective gas permeation methods.; The series of polyimides were found to have high glass transition temperatures (247°C–368°C) and very good short-term thermal stability as shown by TGA, despite the partially aliphatic character of DAPI. The 5,5 ′-[2,2,2-trifluoro-1-(trifluoromethyl)ethylidene]bis-1,3-isobenzen efurandione (6FDA)/DAPI system also exhibited low weight loss under nitrogen at 400°C.; The rigid, bulky and isomeric structure of DAPI in the repeat unit imparted film forming characteristics that allowed production of solvent cast membranes which displayed a range of O2 permeability and O2/N 2 selectivity characteristics. High O2 permeabilities were observed for polyimides in which the DAPI structure predominated in relation to the overall polymer repeat unit. The more flexible dianhydrides were thought to result in a more tightly packed polymer conformation which decreased the rate of gas penetration through thin films. The DAPI/3,3′,4,4 ′-benzophenonetetracarboxylic dianhydride (BTDA) system showed the best combination of O2 permeability and O2/N 2 selectivity values.; High molecular weight polyimides based on DAPI and BTDA were synthesized by three different routes. The ester-acid and thermal imidization methods produced polyimides with the highest Tgs and best thermal stability in air, as compared to the chemical imidization procedure.; Polyimides derived from 6FDA were synthesized by the high temperature solution imidization method. Thin films, cast from NMP, were tough and creasable and afforded high Tg (>295°C) systems with good thermal stability. When combined with rigid diamines, 6FDA contributed to high O2 permeation and moderate O2/N2 selectivity.; Polyimide systems containing hydroxyl moieties in the repeat unit were also investigated. Incorporation of hydroxyl moieties in the repeat unit enhanced chain stiffness via intermolecular hydrogen bonding and showed Tg increases of 30°C. Hydroxyl moieties also decreased the thermal stability values typically observed for polyimides. High O2/N2 selectivity was achieved with all of the 4,4′-diaminobiphenyl-3,3 ′-diol (HAB) containing polymers. However, these materials also had low O2 permeabilities. (Abstract shortened by UMI.)... |
