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Various Aromatic Dianhydrides (various + aromatic_dianhydride)
Selected AbstractsSynthesis and properties of fluorinated polyimides based on 1,4-bis(4-amino-2-trifluoromethylphenoxy)-2,5-di- tert -butylbenzene and various aromatic dianhydridesJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 9 2004Chin-Ping Yang Abstract A novel fluorinated diamine monomer, 1,4-bis(4-amino-2-trifluoromethylphenoxy)-2,5-di- tert -butylbenzene (2), was prepared through the nucleophilic substitution reaction of 2-chloro-5-nitrobenzotrifluoride and 2,5-di- tert -butylhydroquinone in the presence of potassium carbonate, followed by catalytic reduction with hydrazine and Pd/C. Fluorinated polyimides (5a,5f) were synthesized from diamine 2 and various aromatic dianhydrides (3a,3f) via thermal or chemical imidization. These polymers had inherent viscosities of 0.77,1.01 dL/g. The 5 series polyimides were soluble in N -methyl-2-pyrrolidone, N,N -dimethylacetamide, and N,N -dimethylformamide and were even soluble in dioxane, tetrahydrofuran, and dichloromethane. 5(C) showed cutoff wavelengths between 363 and 404 nm and yellowness index (b*) values of 6.5,40.2. The polyimide films had tensile strengths of 93,114 MPa, elongations to break of 9,12%, and initial moduli of 1.7,2.1 GPa. The glass-transition temperatures were 255,288 °C. The temperatures of 10% weight loss were all above 460 °C in air or nitrogen atmospheres. In comparison with a nonfluorinated polyimide series based on 1,4-bis(4-aminophenoxy)-2,5-di- tert -butylbenzene, the 5 series showed better solubility and lower color intensity, dielectric constants, and moisture absorption. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2272,2284, 2004 [source] Synthesis and characterization of new polybenzimidazopyrrolones derived from pyridine-bridged aromatic tetraamines and dianhydridesJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 8 2004Jin-Gang Liu Abstract A series of new polybenzimidazopyrrolones (polypyrrolone, PPy) were synthesized by polycondensation of pyridine-bridged aromatic tetraamines, including 2,6-bis (3,,4,-diaminophenyl)-4-phenylpyridine and 2,6-bis(3,,4,- diaminophenyl)-4-(3,-trifluoromethyl)phenyl pyridine, with various aromatic dianhydrides. Experimental results indicated that the PPys, multiaromatic conjugated and semiladder polymers, showed good thermal stabilities with thermal-decomposition temperatures of about 500 °C and residual weight retention at 750 °C as high as 84%. PPy films could be obtained by casting the precursor solution, poly(amide amino acid) on glass substrate, followed by thermal dehydrating at elevated temperatures. The polymer films exhibited excellent alkaline hydrolysis resistance, which retained their original shapes and toughness after boiling 7 days in 10% sodium hydroxide solution. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1845,1856, 2004 [source] Effects of diamines and their fluorinated groups on the color lightness and preparation of organosoluble aromatic polyimides from 2,2-bis[4-(4-amino-2-trifluoromethylphenoxy)phenyl]-hexafluoropropaneJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 7 2003Chin-Ping Yang Abstract To investigate the position and amount of the CF3 group affecting the coloration of polyimides (PIs), we prepared 2,2-bis[4-(4-amino-2-trifluoromethylphenoxy)phenyl]hexafluoropropane (2) with four CF3 groups with 2-chloro-5-nitrobenzotrifluoride and 2,2-bis(4-hydroxyphenol)hexafluoropropane. A series of soluble and light-colored fluorinated PIs (5) were synthesized from 2 and various aromatic dianhydrides (3a,3f). 5a,5f had inherent viscosities ranging from 0.80 to 1.19 dL/g and were soluble in amide polar solvents and even in less polar solvents. The glass-transition temperatures of 5 were 221,265 °C, and the 10% weight-loss temperatures were above 493 °C. Their films had cutoff wavelengths between 343 and 390 nm, b* values (a yellowness index) ranging from 5 to 41, dielectric constants of 2.68,3.01 (1 MHz), and moisture absorptions of 0.03,0.29 wt %. In a comparison of the PI series 6,8 based on 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane, 2,2-bis[4-(4-amino-2-trifluoromethylphenoxy)phenyl]propane, and 2,2-bis[4-(4-aminophenoxy)phenyl]propane, we found that the CF3 group close to the imide group was more effective in lowering the color; this means that CF3 of 5, 7, and 8f was more effective than that of 6c. The color intensity of the four PI series was lowered in the following order: 5 > 7 > 6 > 8. The PI 5f, synthesized from diamine 2 and 4,4,-hexafluoroisopropylidenediphthalic anhydride, had six CF3 groups in a repeated segment, so it exhibited the lightest color among the four series. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 922,938, 2003 [source] New organosoluble polyimides with low dielectric constants derived from bis[4-(2-trifluoromethyl-4-aminophenoxy)phenyl] diphenylmethyleneMACROMOLECULAR SYMPOSIA, Issue 1 2003Der-Jang Liaw Abstract A new kink diamine with trifluoromethyl group on either side, bis[4-(2-trifluoromethyl-4-aminophenoxy)phenyl]diphenylmethane(BTFAPDM), was reacted with various aromatic dianhydrides to prepare polyimides via poly (amic acid) precursors followed by thermal or chemical imidization. Polyimides were prepared using 3,3,, 4,4,-biphenyltetracarboxylic dianhydride(1), 4,4,-oxydiphthalic anhydride(2), 3,3,,4,4,-benzophenonetetracarboxylic dianhydride (3), 4,4,-sulfonyldiphthalic anhydride(4), and 4,4,-hexafluoroisopropylidene-diphathalic anhydride(5). The fluoro-polyimides exhibited low dielectric constants between 2.46 and 2.98, light color, and excellent high solubility. They exhibited glass transition temperatures between 227 and 253°C, and possessed a coefficient of thermal expansion (CTE) of 60-88 ppm/°C. Polymers PI-2, PI-3, PI-4, PI-5 showed excellent solubility in the organic solvents: N -methyl-2-pyrrolidinone (NMP), N,N -dimethylacetamide (DMAc), N,N -dimethylformamide (DMF), dimethyl sulfoxide (DMSO), pyridkie and tetrahydrofuran (THF). Inherent viscosity of the polyimides were found to range between 0.58 and 0.72 dLg-1. Thermogravimetric analysis of the polyimides revealed a high thermal stability decomposition temperature in excess of 500°C in nitrogen. Temperature at 10 % weight loss was found to be in the range 506-563°C and 498-557°C in nitrogen and air, respectively. The polyimide films had a tensile strength in the range 75-87 MPa; tensile modulus, 1.5-2.2 GPa; and elongation at break, 6-7%. [source] | ||||||||||