We have determined the gas transport properties of He, H 2 , O 2 , N 2 , and CO 2 for 6FDA-durene homopolymer and 6FDA-durene/pPDA copolyimides. The 6FDAdurene exhibits the highest permeability with the lowest selectivity. Permeability of copolymers decreases with increasing 6FDA-pPDA content, while permselectivity increases with an increase in 6FDA-pPDA content. 6FDA-durene/pPDA (50/50) and 6FDA-durene/pPDA (20/80) materials have O 2 and CO 2 permeabilities greater than those calculated from the addition rule of the semilogarithmic equation. These higher deviations from the additional rule of the semilogarithmic equation are mainly attributed to the fact that these copolyimides have higher solubility coefficients than those calculated from the additive rule. The T g s of 6FDA-durene/pPDA copolyimides decrease with an increase in 6FDA-pPDA content. T g s predicted from the Fox equation are lower than the experimental data, and the their difference increases with an increase in pPDA content, implying the copolyimides of 6FDA-durene/pPDA may have greater interstitial space among chains because of the conformation difference, and thus create more fraction free volume compared with the ideal case of simple volume addition. Density measurements also suggest these two copolymers have greater free volumes and the fractions of free volume, which supporting the gas transport results. The thermal stability and ␤-relaxation temperature have also been studied for these copolymers.

We have determined the gas transport properties of He, H2, O2, N2, and CO2 for 6FDA‐durene homopolymer and 6FDA‐durene/pPDA copolyimides. The 6FDA‐durene exhibits the highest permeability with the lowest selectivity. Permeability of copolymers decreases with increasing 6FDA–pPDA content, while permselectivity increases with an increase in 6FDA–pPDA content. 6FDA‐durene/pPDA (50/50) and 6FDA‐durene/pPDA (20/80) materials have O2 and CO2 permeabilities greater than those calculated from the addition rule of the semilogarithmic equation. These higher deviations from the additional rule of the semilogarithmic equation are mainly attributed to the fact that these copolyimides have higher solubility coefficients than those calculated from the additive rule. The Tg s of 6FDA‐durene/pPDA copolyimides decrease with an increase in 6FDA–pPDA content. Tg s predicted from the Fox equation are lower than the experimental data, and the their difference increases with an increase in pPDA content, implying the copolyimides of 6FDA‐durene/pPDA may have greater interstitial space among chains because of the conformation difference, and thus create more fraction free volume compared with the ideal case of simple volume addition. Density measurements also suggest these two copolymers have greater free volumes and the fractions of free volume, which supporting the gas transport results. The thermal stability and β‐relaxation temperature have also been studied for these copolymers. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 2703–2713, 2000

ExperimentalMaterials: The PLED configuration used in this work was ITO/ PEDOT:MPS(50 nm)/polyfluorene:plystyrene(PS)(80 nm)/Ca(30 nm)/ Ag(250 nm). The ITO glass substrate was a product of Samsung Corning Co. and had a sheet resistance of 10 X/square. MPS used as a PE-DOT modifier was purchased from Dow Corning Co. PEDOT/polystyrenesulfonate (Bayer Co. Ltd.) was used as a HTL, and polyfluorene-based green copolymer (Green K2, Dow Chemical Co.):PS (1:1) blend was used as an LEP. A Ca and Ag double layer was used as a cathode for the devices.Device Fabrication: ITO glass substrates were cleaned with acetone and isopropyl alcohol in an ultrasonic bath for 15 min, respectively, and were dried at 120 C for 2 h before use. The ITO glass substrates were exposed to ultraviolet(UV)/ozone for 15 min and were spin coated with an aqueous PEDOT:MPS solution. The PEDOT:MPS solution was prepared by dissolving MPS in PEDOT solution at concentrations of 0, 0.1, 0.2, and 0.5 wt.-%. The mixed solution was stirred for 60 min to hydrolyze MPS. The hydrolyzed PEDOT:MPS solution was spin-coated on a UV/ozone-treated ITO substrate at a spin speed of 2000 rpm (rpm = revolutions per minute) to get a 500 nm thick HTL layer. After that, the PEDOT:MPS coated substrate was baked at 200 C for 10 min to remove residual solvent. The I±V±L characteristics and lifetime of PEDOT:MPS devices were measured with spin-coated devices. Spin coating of the LEP dissolved in toluene was carried out at a spin speed of 3000 rpm and 80 nm LEP thin film was obtained. The substrates were baked at 90 C for 60 min before cathode deposition. For LITI devices, LEP was spin coated on a poly(ethyleneterephthalate) donor film with a light to heat conversion layer at a thickness of 80 nm. The transfer of the LEP to the HTL layer was performed with a Nd:YAG laser with a total power of 8 W. The LEP-coated donor film was placed on the HTL-coated substrates and was closely adhered to the substrates using vacuum chuck to remove the gap between the donor film and the substrates. The donor film was then exposed to the Nd:YAG laser beam and the exposed LEP was transferred to the substrates. After LITI transfer, the donor film was peeled off and the substrate was baked at 90 C for 60 min. After baking, Ca was deposited at a rate of 0.5 s ±1 followed by Ag evaporation at a rate of 5 s ±1 in a high vacuum chamber (» 10 ±7 torr) as a cathode for devices. The thickness of Ca and Ag was 30 nm and 230 nm, respectively. After cathode deposition, the devices were encapsulated with a metal can and barium oxide.Measurements: I±V±L characteristics of the devices were measured with a PR 650 spectrophotometer and lifetime results were obtained at a constant current mode at a brightness of 500 cd m ±2 . The indium diffusion in PEDOT:MPS devices was analyzed with XPS. The XPS measurements of the coated samples were carried out in ultra-high vacuum chamber ESCALAB 250(VG scientific) with a monochromated Al Ka source was used for analysis; etching of the samples was performed with Ar ion sputter...

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A series of amorphous fluoro-polyetherimides based on 2,2'-bis(3,4-dicarboxyphenyl) hexafluropropane dianhydride (6FDA) and di-ether-containing diamines 4,4'-bis(3-aminophenoxy)diphenyl sulfone (m-SED), 4,4'-bis(4-aminophenoxy)diphenyl sulfone (pSED), 4,4-bis(4-aminophenoxy)diphenyl propane (BPADE) were synthesized. These melt processable polyetherimide polymers from pSED and BPADE showed excellent electrical properties. The dielectric constants, 2.74 and 2.65 at 10 M H z respectively, are lower than commercially available polyetherimide ULTEM@ 1000, and polyimide Kapton@ H films. In addition, we found that trifluoromethyl groups-containing polyimides not only show extraordinaxy electrical properties, but they also exhibit excellent long-term thermo-oxidative stability and reduced water absorption relative to non-fluorinated polyimides. The weight retention of these fluoro-polyetherimides at 3 15°C for 300 h in air varies from 93% to 98%. Whereas, their moisture absorption at 100 RH at 50°C was in the range of 0.3% to 1.05%, which is much lower than those of Ultem 1000 and Kapton H. In the case of fluoro-polyetherimides from pSED and m-SED @ara and meta isomers) diamines with 'ether' and sulfonyl (-SO,-) spacer groups, the d-spacing and Tg values decreased from 4 . 7 d to 4.56A and 293°C to 244°C respectively. Similarly, the transparency of these polymer films (in the range of 80% to 90%) at 500 nm solar wavelength was higher than Ultem 1000 and Kapton H.