Trifluoromethyl)-4,4′-diaminobiphenyl Research Articles

Synthesis and characterization of colorless polyimide nanocomposite films containing pendant trifluoromethyl groups

A series of colorless polyimide (PI) nanocomposite films were synthesized from 2,2′-bis(3,4-dicarboxyphenyl) hexafluoropropane dianhydride (6FDA) and 2,2′-bis(trifluoromethyl)-4,4′-diaminobiphenyl (TFDB) with various organoclay contents by solution intercalation polymerization to poly(amic acid)s, followed by thermal imidization. The variation with the organoclay content of the thermomechanical properties, morphology, and optical transparency of the hybrids was examined at organoclay loadings ranging from 0 to 1.0 wt%. The hybrid films showed high optical transparency and almost no color, with cut-off wavelengths ranging from 352 and 356 nm and very low b* values of 1.19–1.77. The hybrid PI films showed good thermal properties with a glass transition temperature of 280–287 °C. Most films did not show any significant thermal decomposition below 490 °C. The addition of only a small amount of organoclay was sufficient to improve the tensile properties of the PI films with maximum enhancement being observed at 0.25 wt% organoclay. Moreover, these PI hybrids also had low coefficients of thermal expansion (CTE).

Transparent Flexible Substrates Based on Polyimides with Aluminum Doped Zinc Oxide (AZO) Thin Films

In this paper, transparent flexible substrates based on polyimides (PIs) with aluminum doped zinc oxide (AZO) thin films for organic electroluminescent devices have been prepared. PI film based on 2,2'-bis-(3,4-dicarboxyphenyl) hexafluoropropanedianhydride (6FDA) and 2,2'-bis-(trifluoromethyl)-4,4'-diaminobiphenyl (TFDB) were used for transparent flexible substrates. AZO thin films were prepared at two substrate deposition temperatures of 100/spl deg/C and 200/spl deg/C with a typical radio-frequency (r.f.) planar magnetron sputtering system. The sheet resistance and the optical transmission properties for AZO films on the fluorinated PI substrate were comparable with those for the AZO films on a glass substrate. The substrate properties were better when the deposition temperature was higher.

Polyimide as a Plastic Substrate for the Flexible Organic Electroluminescent Device

AbstractIn this work, transparent flexible substrates based on polyimides(PI) with indium tin oxide (ITO) thin films for organic electroluminescent devices have been prepared. 2,2'-bis-(3,4- dicarboxyphenyl) hexafluoropropanedianhydride (6FDA) and 2,2'-bis-(trifluoromethyl)-4,4'- diaminobiphenyl (TFDB) PI films were used for transparent flexible substrates. ITO thin films were prepared at two substrate deposition temperatures of 25°C and 150°C with a typical radio- frequency (r.f.) planar magnetron sputtering system. The sheet resistance and the optical transmission properties of the fluorinated PI substrate were comparable with those for the slide glass substrate. The substrate properties are better when the deposition temperature is higher. SiO2 coating onto the fluorinated PI substrate by sol-gel reaction was also attempted to improve the optical transmission of the ITO/PI substrate. It was found that the coating of SiO2 affected on the morphology of the PI substrates.

Soluble Polyimides Containing Benzimidazole Rings for Interlevel Dielectrics

New soluble polyimides with improved adhesion to copper were synthesized from 6,4‘-diamino-2-phenylbenzimidazole (BIA) and 2,2‘-bis(trifluoromethyl)-4,4‘-diaminobiphenyl (TFDB) with 3,3‘,4,4‘-benzophenone tetracarboxylic dianhydride (BTDA) via one-pot synthetic method using N-methylpyrrolidone (NMP) as a solvent. Precipitation or gelation did not occur during imidization, and the synthesized polyimides having inherent viscosity values of 0.86−1.74 dL/g were dissolved well in polar aprotic solvents and phenolic solvents. Flexible and fingernail-creasable films were formed on casting. Tg values of the polyimides were in the range of 320−351 °C and 5% weight loss in nitrogen occurred above 540 °C in all cases. The polyimides containing an equimolar amount of BIA and TFDB showed good adhesion to copper without any adhesion promoters. Water absorption and dielectric constant of the polyimides were in the ranges of 0.57−1.18% and 2.74−2.94, respectively. The polyimides containing a higher content of benzimidazo...

Surface characterization of fluorinated polyimide films grown by vapor deposition polymerization

Vapor deposition polymerization (VDP) was used to prepare fluorinated polyimide films. The process utilizes the coevaporation of 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6FDA) and 2,2′-bis(trifluoromethyl)-4,4′-diaminobiphenyl (TFDB) monomers. We characterized the surface by x-ray photoelectron spectroscopy (XPS), scanning electron microscopy, atomic force microscopy (AFM), and scanning tunneling microscopy (STM). The XPS analysis showed that the film stoichiometry greatly depended on the ratio of source effusion rates, and that a 6FDA/TFDB pressure ratio of 1:10 was best for obtaining stoichiometric 6FDA/TFDB polyimide. The surface structure image obtained by AFM was clearly different from that of spin-cast films. The surface morphology of the VDP films was characterized by an accumulation of parallel rod shaped structures, whereas that of the spin-cast one was a rough structure. The surface morphology of the VDP grown films at the initial growth state was also found to be a vertical stripe structure according to STM results.

Property Control Of New Fluorinated Copolyimides And Their Applications

ABSTRACTNew fluorinated copolyimides are synthesized with 2,2′-bis(trifluoromethyl)-4,4′- diaminobiphenyl (TFDB) and a mixture of 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6FDA) and pyromellitic dianhydride (PMDA). The thermal expansion coefficient decreases with decreasing 6FDA content, because the hexafluoroisopropylidene group makes the main chain flexible. The refractive index decreases with increasing 6FDA content, because the fluorine content increases. The thermal expansion coefficient can be controlled between -0.5 × 10−5 and 8×10−5 /°C, and the refractive index can be controlled between 1.556 and 1.647 at 589.3 nm, by changing the 6FDA content. The polyimides and copolyimides from TFDB can be used in optical filters because of their high optical transparency and low thermal expansion coefficient. They are expected to be used in optical waveguides because of their high optical transparency and refractive index control.

Organo-Soluble, Segmented Rigid-Rod Polyimides: Synthesis and Properties

ABSTRACTSeveral segmented, rigid-rod polyimides have been prepared that are soluble in organic solvents in their fully imidized form. The polymers were prepared from commercial dianhydrides and 2,2′-bis(trifluoromethyl)-4,4′-diaminobiphenyl (TFMB). Their intrinsic viscosities ranged from 1.0 to 4.9 dL/g. Tough, colorless films could be cast from m-cresol solutions at 100°C. The polymers had glass transition temperatures (Tgs) above 275°C and displayed outstanding thermal and thermo-oxidative stability. Fibers were prepared from the 3,3′,4,4′-tetracarboxybiphenyl dianhydride (BPDA) based polymers that had moduli of 130 GPa and tensile strengths of 3.2 GPa. The thermal expansion coefficients and dielectric constants of thin films (20–25 μm) of the polymers were as low as −2.40×10−6 and 2.5, respectively.