Synthesis and properties of novel aromatic poly(ester-imide)s bearing 1,5-bis(benzoyloxy)naphthalene units

Design and synthesis of high heat-resistant, soluble, and hydrophobic fluorinated polyimides containing pyridine and trifluoromethylthiophenyl units

In this study, a novel diamine monomer, 4-(4-trifluoromethylthiophenyl)-2,6-bis(4-aminophenyl)pyridine (FTPAP) was synthesized through two-step reaction from 4-trifluoromethylthiobenzaldehyde and 4-nitroacetophenone as raw materials, and then the structure of FTPAP was characterized by Fourier transform infrared (FTIR) spectroscopy, nuclear magnetic resonance, and mass spectrometry. A series of fluorinated polyimides were prepared from FTPAP with five commercial dianhydrides, namely, pyromellitic dianhydride, biphenyl tetracarboxylic dianhydride, oxydiphtahalic anhydride, benzophenone tetracarboxylic dianhydride, and 4,4′-(hexafluoroisopropylidene) diphthalic anhydride. The structure and performance of the fluorinated polymers were fully characterized by FTIR, differential scanning calorimetry, thermogravimetric analysis, and wide-angle X-ray diffraction (WAXD). The inherent viscosity of polymers ranged from 0.41 to 1.45 dL g−1. These polymers displayed good solubility in polar aprotic solvents, such as N, N-dimethylformamide, N, N-dimethylacetamide, dimethyl sulfoxide, and N-methyl-2-pyrrolidone, at room temperature or on heating. Furthermore, they exhibited outstanding thermal stability with glass transition temperatures beyond 305°C, and the temperature of 10% weight loss was in the range of 514–573°C with more than 56% residue at 800°C under nitrogen. Moreover, they showed high optical transparency with the cutoff wavelengths in the range of 385–457 nm and excellent hydrophobic property with contact angle in the range of 82.8–97.6°. In addition, the results of WAXD indicated that all of the polymers presented amorphous structure.

New organosoluble aromatic poly(esterimide)s containing pendent pentadecyl chains

A new diimide dicarboxylic acid, namely 2,2′-(4-pentadecyl-1,3-phenylene)bis(1,3-dioxoisoindoline-5-carboxylic acid), containing preformed imide rings and pentadecyl chain, was synthesized by the reaction of 4-pentadecylbenzene-1,3-diamine with trimellitic anhydride. A series of new aromatic poly(esterimide)s (PEIs) was synthesized using diphenylchlorophosphate-activated direct polycondensation of 2,2′-(4-pentadecyl-1,3-phenylene)bis(1,3-dioxoisoindoline-5-carboxylic acid), with five commercially available bisphenols, namely 4,4′-isopropylidenediphenol (I), 4,4′-(hexafluoroisopropylidene)diphenol (II), 4,4′-oxydiphenol (III), 4,4′-biphenol (IV), and 4,4′-(9-fluorenylidene)diphenol (V) in the presence of pyridine and lithium chloride. Inherent viscosities of PEIs were in the range 0.54–0.83 dL g−1 in chloroform (CHCl3) at 30 ± 0.1°C. PEIs containing pendent pentadecyl chains were soluble in organic solvents such as CHCl3, m-cresol, N, N-dimethylacetamide, 1-methyl-2-pyrrolidinone, pyridine, and nitrobenzene. Tough, transparent, and flexible films of PEIs could be cast from their CHCl3 solutions. PEIs exhibited glass transition temperature in the range 145–198°C. The temperature at 10% weight loss of PEIs, determined by thermogravimetric analysis under the nitrogen atmosphere, was in the range of 450–470°C indicating good thermal stability.

Comparative study on polyimides derived from isomeric diphenylsulfonetetracarboxylic dianhydrides

In this study, three diphenylsulfonetetracarboxylic dianhydride (DSDA) isomers namely 2,2′,3,3′-DSDA (3,3′-DSDA), 2,3,3′,4′-DSDA (3,4′-DSDA) and 3,3′,4,4′-DSDA (4,4′-DSDA) were prepared from the corresponding diphenylthioethertetracarboxylic dianhydride isomers. Based on the three DSDA isomers, a series of isomeric polyimides were prepared. The properties, such as film-forming ability, solubility, wide-angle x-ray diffraction, thermal and mechanical properties as well as rheological behavior, were compared among the isomeric polyimides. It was found that 4,4′-DSDA-based polyimides had much better film-forming ability than 3,3′-DSDA- and 3,4′-DSDA-based polyimides. 3,4′-DSDA-based polyimides had better solubility than 3,3′-DSDA- and 4,4′-DSDA-based polyimides. Furthermore, for a given diamine, the glass transition temperatures of the polyimides from the three DSDA isomers decreased in the order of 3,3′-DSDA > 3,4′-DSDA > 4,4′-DSDA, while the 5% weight loss temperatures in both air and nitrogen atmospheres of the polyimides mainly increased in the order of 3,3′-DSDA < 3,4′-DSDA < 4,4′-DSDA. Moreover, 3,4′-DSDA- and 4,4′-DSDA-based polyimides showed much better melt stability than 3,3′-DSDA-based polyimide.

Synthesis and characterization of highly soluble and optically transparent polyimides derived from novel fluorinated pyridine-containing aromatic diamine

A novel fluorinated pyridine-containing aromatic diamine monomer, 4-phenyl-2,6-bis[2-(4-amino-2-trifluoromethyphenoxy)phenyl]pyridine ( o, p-6FPAPP), was prepared in a three-step synthetic route. This aromatic diamine was then employed to synthesize a series of fluorinated pyridine-containing polyimides (PIs) by polycondensation with various aromatic dianhydrides via the conventional two-step method. The inherent viscosities of the resulting poly(amic acid)s (PAAs) and PIs were in the range of 0.71–0.89 and 0.62–0.84 dL/g; all the PIs obtained by chemical imidization were readily soluble in common organic solvents such as N, N-dimethylformamide (DMF), N, N-dimethylacetamide (DMAc), N-methyl-2-pyrrolidone (NMP), dimethyl sulfoxide (DMSO), tetrahydrofuran (THF) and so on. Meanwhile, transparent, strong and flexible PI films were obtained, which had good thermal stability, with the glass transition temperature ( Tg) of 195.2°C–232.7°C, the temperature at 10% weight loss of 530.2°C–546.0°C in nitrogen atmosphere, and good optical transparency with the cutoff wavelengths of 354–382 nm, as well as outstanding mechanical properties with tensile strengths of 96.4–105.8 MPa, tensile modulus of 1.57–1.88 GPa and elongations at break of 9.5%–13.4%. The PI films were also found to possess low water uptake of 0.52%–0.67%.

Design and preparation of novel fluorescent polyimides containing ortho-linked units and pyridine moieties

A novel pyridine-containing aromatic diamine monomer, 4-[4-hydroxyphenyl]-2,6-bis[4-(2-aminophenoxy)phenyl]pyridine (p,o-HAPP), was synthesized by a modified Chichibabin reaction of p-Hydroxybenzaldehyde and a substituted acetophenone, 4-(2-nitrophenoxy)acetophenone (p,o-NPAP), followed by a reduction of the resulting dinitro compound 4-[4-hydroxyphenyl]-2,6-bis[4-(2-nitrophenoxy)phenyl]pyridine with Pd/C and hydrazine monohydrate. The aromatic diamine was employed to prepare a series of pyridine-containing polyimides (PIs) by polycondensation with various aromatic dianhydrides in N,N-dimethylformamide (DMF) via the conventional two-step method. The inherent viscosities of the resulting poly(amic acids) and PIs were in range of 0.62-0.76 and 0.52-0.64 dL/g, respectively. The obtained novel PIs exhibited high solubility in common organic solvents, such as m-Cresol, DMF, N,N-dimethylacetamide, dimethylsulfoxide, N-methylpyrrolidone (NMP), tetrahydrofuran, and chloroform. Meanwhile, flexible PI films were obtained, which had excellent thermal stability, with the glass transition temperature (T g) of 259.8-323.4 °C and the temperature at 10% weight loss of 485.5-576.4 °C in nitrogen atmosphere. The protonated polymer showed UV-vis absorption in the region 200-400 nm and displayed strong fluorescence intensity (470 nm) in NMP solution.