Synthesis of photoreactive polyimide having indan structure

Polyimide containing an indan unit and alkyl moiety with a high molecular weight was prepared from 5,7‐diamino‐1,1,4,6‐tetramethylindan and 3,3′,4,4′‐benzophenone tetracarboxylic dianhydride. This polyimide was amorphous and soluble in common organic solvents, such as tetrahydrofuran, chloroform, and cyclopentanone. Thermogravimetry of the polyimide showed good thermal stability, indicating that a 10% weight loss of the polyimide was observed at 500 °C in nitrogen. The glass‐transition temperature of the polyimide was not observed by DSC measurement between room temperature and 400 °C at a heating rate of 10 °C/min (Apparatus: DSC3100 MAC Science Co., Ltd.). Transparency of the polyimide at 365 nm was 80%. The polyimide acted as a photosensitive resist of negative type by UV radiation. The resist had a sensitivity of 31 mJ/cm² and a contrast of 2.3 when it was developed with cyclopentanone at room temperature. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 40: 423–428, 2002     

Aromatic poly(sulfone sulfide amide imide)s as new types of soluble thermally stable polymers

A new diamine monomer containing flexible sulfone, sulfide, and amide units was prepared via three steps. Nucleophilic chloro displacement reaction of 4‐aminothiophenol with 4‐nitrobenzoyl chloride in the presence of propylene oxide afforded N‐(4‐mercapto‐phenyl)‐4‐nitrobenzamide and subsequent reduction of the nitro intermediate led to 4‐amino‐N‐(4‐mercapto‐phenyl)benzamide. Two moles of this amino thiophenol compound was reacted with bis‐(4‐chloro phenyl)sulfone to provide a novel diamine monomer. The diamine was reacted with aromatic dianhydrides to form polyimides via a two‐step polycondensation method, formation of poly(amic acid)s, followed by chemical imidization. The resulting polymers were characterized and their physical properties including thermal behavior, thermal stability, solubility and inherent viscosity were studied. Copyright © 2007 John Wiley & Sons, Ltd.     

Synthesis and crosslinking of cyano-substituted polyamides and polyimides prepared from 1-(2,2-dicyano-1-hydroxyviyl)-3,5-diaminobenzene,sodium salt

3,5-Dinitrobenzoyl chloide was condensed with malononitrile in the presence of sodium hydroxide under phase-transfer conditions to afford 1-(2,2-dicyano-1-hydroxyvinyl)-3,5-dinitrobenzene, sodium salt, which was catalytically hydrogenated to the corresponding diamine. The latter was used as starting material for the preparation of unsaturated cyanosubstituted polyamides and polyimides. The polymers were soluble in polar aprotic solvents, dilute sodium hydroxide, and certain strong inorganic and organic acids. Upon curing at 300°C for 65 h, crosslinked polymers were obtained that were stable up to 392–404°C in N₂ or air and afforded an anaerobic char yield of 60–71% at 800°C. Their glass transition temperatures as determined by thermal mechanical analysis (TMA) were 221–275°C. © 1995 John Wiley & Sons, Inc.     

Synthesis and Characterization of Novel Polyimides Based on Pyridine-containing Diamine

A new aromatic diamine monomer containing pyridine unit, 2,6-bis （4-aminophenoxy- 4＇-benzoyl）pyridine（BABP）, was synthesized in three steps, starting from 2,6-pyridinedicarboxyl chloride. A series of novel pyridine-containing polyimides were prepared v/a the polycondensation of BABP with various aromatic dianhydrides through poly（amic acid） precursors, and thermal or chemical imidization of the precursors. The polyimides exhibit desirable properties, e.g., good solubility in N-methyl-2-pyrrolidone and m-cresol, excellent thermal stability and film-forming capability, as well as high inherent viscosity, indicating high molecular weight.     

New perylene polyimides containing p‐n diblocks for sensitization in TiO2 solar cells

Three novel perylene polyimides (PPIs) containing p‐n diblock units were designed and synthesized for use in dye‐sensitized mesoporous TiO₂ solar cells. They all dissolve in m‐cresol and N‐methyl‐2‐pyrrolidone (NMP). Their visible light absorption, electrochemical and photoelectrochemical properties were systematically studied. The polyimides have band gap energies of 2.16, 2.19 and 2.25 eV deduced from ultraviolet–visible absorption spectra, and electron affinity (E_a) and ionization potential (IP) of ?3.93 and 6.10 eV for PPI1, ?3.94 and 6.13 eV for PPI2, ?3.93 and 6.59 eV for PPI3, respectively, deduced from cyclic voltammogram. Experimental data show that introduction of 4,4′‐bisaminetriphenylamine cannot only greatly enhance optic‐electro conversion efficiency, but also enhance the dissolubility which in favorable for making the devices. The relationship of structure and properties of PPI is discussed and the mechanism of photocurrent generation is explained. Copyright © 2004 John Wiley & Sons, Ltd.     

Organosoluble and transparent polyimides derived from alicyclic dianhydride and aromatic diamines

Organosoluble polyimides were synthesized with the alicyclic dianhydride 1,8‐dimethylbicyclo[2,2,2]oct‐7‐ene‐2,3,5,6‐tetracarboxylic dianhydride and aromatic diamines. The polyimides possessed good solubility both in strong dipolar solvents and in common solvents; the thermal decomposition temperature of the polyimides exceeded 420 °C. Strong and flexible films of the polyimides, with the cutoff of ultraviolet–visible absorption lower than 310–320 nm, exhibited good features as the alignment layers for nematic liquid crystals with pretilt angles of 1.5–2.9°. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 40: 110–119, 2002     

Synthesis and Luminescence Property of 4,4＇-Bis（2,2-di（4-fluorophenyl）vinyl）biphenyl for Organic Blue-Light-Emitting Diodes

The novel fluorinated distyrylarylene, 4,4＇-bis（2,2-di（4-fluorophenyl）vinyl）biphenyl （DFPVBi）, was synthesized and fully characterized. The structure was confirmed with IR, 1↑H NMR, 13↑C NMR, 19↑F NMR and MS analyses. Its electronic and photoluminescence properties were investigated by UV-Vis absorption, cyclic voltammetry and fluorescence spectroscopy. The energy levels of the highest occupied molecular orbital （HOMO） and the lowest unoccupied molecular orbital （LUMO） are --5.77 and --2.75 eV, respectively. The electroluminescence proper- ties of the organic light-emitting diode fabricated by DFPVBi were also studied. The device exhibits a pure blue emission peaked at 454 nm, which indicates a maximum luminance of 5872 cd/m ^2 at 14.2 V and a maximum current efficiency of 2.82 cd/A at 10V, respectively.     

Pyrolysis study of fluorinated sol-gel silica

Fluorinated silica gels at various fluorine content were prepared via sol-gel by hydrolysis of 3,3,3-trifluoropropyltrimethoxysilane and tetraethoxysilane mixtures. The gels, of nominal stoichiometry Si(CH₂CH₂CF₃)_XO_(2-X/2)(X=0.1-1), were characterized by FT-IR, X-ray photoelectron spectroscopy (XPS) and N₂ adsorption analysis. The thermal stability of the fluorinated samples was investigated by coupling thermogravimetric measurements with mass spectrometric and gas chromatographic analyses of the evolved gaseous species. The chemical reactions occurring in the gel matrices during heating were siloxane chain rearrangements involving condensation between residual hydroxyl and ethoxyl groups in the 100-350°C temperature range, whereas the thermal decomposition of the fluoroalkyl groups were observed at higher temperatures (450-600°C). The release of the fluoroalkyl moieties also involved C-F/Si-O bond exchanges inside the siloxane chains, with gas-phase evolution of different fluorinated silicon units. This revised version was published online in July 2006 with corrections to the Cover Date.     

Fully imidized soluble polyimides based on a novel dianhydride: 2,2′-dichloro-4,4′,5,5′-benzophenone tetracarboxylic dianhydride

We have synthesized a novel dianhydride, 2,2′-dichloro-4,4′,5,5′-benzophenone tetracarboxylic dianhydride (DCBTDA). Polyimides were synthesized with DCBTDA or 3,3′,4,4′-benzophenone tetracarboxylic dianhydride (BTDA) and several relatively rigid meta- and para- substituted mononuclear diamines. The BTDA based systems were insoluble in dipolar, aprotic solvents whereas the DCBTDA based polymers displayed enhanced solubility in these solvents. The thermal stability of these polyimides was excellent as measured by 5% weight loss decomposition. The T_g's of the polymers were all above 290°C.