Synthesis and characterization of soluble polyimides based on trifluoromethylated aromatic dianhydride and substitutional diaminetriphenylmethanes

A series of novel and soluble polyimides containing fluorine were synthesized by the polycondensation of fluorine-containing aromatic dianhydride TFDA with substitutional diaminetriphenylmethanes TDPT, FTDPT and 3FTDPT. The composition, structure and properties of the resulting polyimides were studied by means of FT-IR, DSC, TGA and elemental analysis methods, as well as general characterization methods that test solubility or viscosity. The results show that all the novel polyimides were obtained in quantitative yields with inherent viscosities of 0.70-0.76 dL/g, and showed excellent solubility in common organic solvents, such as NMP, DMAc, DMF, DMSO, THF, m-cresol, chloroform and 4-butyrolactone. Meanwhile, their T_g values from DSC are in the range of 265-293 °C, the temperature of 5 and 10% weight loss from TGA are in the range of 460-465 and 513-524 °C in N₂, respectively.     

Synthesis and characterization of novel polyimides derived from pyridine-bridged aromatic dianhydride and various diamines

A new kind of pyridine-bridged aromatic dianhydride monomer, 4-phenyl-2,6-bis[4-(3,4-dicarboxyphenoxy)phenyl]-pyridine dianhydride (PPDA), was successfully synthesized by modified Chichibabin reaction of benzaldehyde and substituted acetophenone, 4-(3,4-dicyanophenoxy)-acetophenone (DCAP), followed by acidic hydrolysis of the intermediate tetranitrile and cyclodehydration of the resulting tetraacid. The pyridine-bridged aromatic dianhydride was employed to synthesized a series of new pyridine-containing polyimides by polycondensation with various aromatic diamines in N-methyl-2-pyrrolidone (NMP) via the conventional two-step method, i.e. ring-opening polycondensation forming the poly(amic acid)s and further thermal or chemical imidization forming polyimides. The inherent viscosities of the resulting polyimides were in the range of 0.49-0.63 dL/g, and most of them were soluble in aprotic amide solvents and cresols, such as N,N-dimethylacetamide (DMAc), NMP, and m-cresol, etc. Meanwhile, strong and flexible polyimide films were obtained, which have good thermal stability with the glass transition temperatures (T_g) of 223-256 °C, the temperature at 5% weight loss of 523-569 °C, and the residue at 700 °C of 52.1-62.7% in nitrogen, as well as have outstanding mechanical properties with the tensile strengths of 70.7-97.6 MPa and elongations at breakage of 7.9-9.7%. Wide-angle X-ray diffraction measurements revealed that these polyimides were predominantly amorphous.     

Synthesis and characterization of novel polyimides based on thiazole-containing diamine

A new kind of aromatic diamine monomer containing thiazole unit,2-amino-5-(4-aminophenyl)-thiazole (AAPT),was synthesized in three steps,starting from 4-nitroacetophenone.A novel thiazole-containing polyimide was prepared via the polycondensation of AAPT with 6FDA by one-step method.The resulting polyimide exhibits excellent solubility,film-forming capability and high thermal resistance.     

Synthesis and characterization of polyimides based on novel isomeric perfluorinated naphthylenediamines

Novel highly fluorinated polyimides containing hexafluoronaphthylene fragment in the main chain were prepared by the two-stage polymerization of 2,7- and 2,6-diaminohexafluoronaphthalenes with 4,4′-oxydiphthalic anhydride: polycondensation in a solution at 80 °C followed by high-temperature solid-state chain extension. The influence of hexafluoronaphthylene fragment isomerism on the key polyimide features - molecular weight, thermal stability, solubility, optical properties - was characterized. Polyimides based on 2,7-diaminohexafluoronaphthalene or easily accessible mixture of isomeric diamines formed the flexible, transparent, and thermostable films.     

Synthesis and properties of novel polyimides from sulfonated binaphthalene dianhydride for proton exchange membranes

A sulfonated dianhydride monomer, 6,6′‐disulfonic‐4,4′‐binaphthyl‐1,1′,8,8′‐tetracarboxylic dianhydride (SBTDA), was successfully synthesized by direct sulfonation of the parent dianhydride, 4,4′‐binaphthyl‐1,1′,8,8′‐tetracarboxylic dianhydride (BTDA), using fuming sulfuric acid as the sulfonating reagent. A series of sulfonated homopolyimides were prepared from SBTDA and various common nonsulfonated diamines. The resulting polymer electrolytes, which contain ion conductivity sites on the deactivated positions of the aryl backbone rings, displayed high proton conductivities of 0.25–0.31 S cm^?1 at 80 °C. The oxidative stability test indicated that the attachment of the ? SO₃H groups onto the dianhydride units did not deteriorate the oxidative stability of the SPI membranes. The better membranes were achieved by the copolymerization of nonsulfonated diamine, SBTDA, and BTDA. Copolymer membrane synthesized from hexane‐1,6‐diamine, SBTDA, and BTDA displayed excellent water stability of more than 1000 h at 90 °C, while its proton conductivity was still at a high level (comparable to that of Nafion 117). Furthermore, the novel block copolymer ( II‐b ) displayed higher proton conductivity compared with the random one ( II‐r ) obviously, probably due to the slightly higher water uptake and better microphase separated morphology. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 2820–2832, 2008     

Synthesis and characterization of some novel aromatic polyimides

Three new diamines 1,2-di(p-aminophenyloxy)ethylene, 2-(4-aminophenoxy)methyl-5-aminobenzimidazole and 4,4-(aminopheyloxy) phenyl-4-aminobenzamide were synthesized and polymerized with 3,3′,4,4′-benzophenone tetracarboxylic acid dianhydride (BP), 4,4′-(hexafluoroisopropyledene)diphthalic anhydride (HF) and 3,4,9,10-perylene tetracarboxylic acid dianhydride (PD) either by one step solution polymerization reaction or by two step procedure. The later includes ring opening poly-addition to give poly(amic acid), followed by cyclodehydration to polyimides with the inherent viscosities 0.62-0.97 dl/g. Majority of polymers are found to be soluble in most of the organic solvents such as DMSO, DMF, DMAc, m-cresol even at room temperature and few becomes soluble on heating. The degradation temperature of the resultant polymers falls in the ranges from 240 °C to 550 °C in nitrogen (with only 10% weight loss). Specific heat capacity at 300 °C ranges from 1.1899 to 5.2541 J g⁻¹ k⁻¹. The maximum degradation temperature ranges from 250 to 620 °C. T_g values of the polyimides ranged from 168 to 254 °C.     

Synthesis of tricyclo[6.2.2.0]dpdecane and tricyclo[6.3.1.0]dodecane ring systems involving intramolecular cyclisation of diazomethyl ketones

2,8-Dimethyltricyclo[6.2.2.0^1,6]dodeca-2,5-diene-4,9-dione ( ), 2,9-dimethyltricyclo [6.3.1.0^1,6]dodeca-2,5-diene-4,10-dione ( ) and 2-methyltricyclo[6.3.1.0^1,6]dodeca-2,5-diene-4,10-dione ( ) have been synthesised for entry into the ring systems of a few tetracyclic diterpenes.     

Synthesis and characterization of polyimides from imidazole-blocked 2,5-bis[(n-alkyloxy)methyl]-1,4-benzene diisocyanates and pyromellitic dianhydride

From imidazole-blocked 2,5-bis[(n-alkyloxy)methyl]-1,4-benzene diisocyanates and pyromellitic dianhydride a series of new rigid-rod polyimides (C_n-PY-PI; n = 4, 6, 8) having linear and flexible (alkyloxy)methyl ((SINGLE BOND)CH₂OC_nH_{2n + 1}; n = 4, 6, 8) side chains were prepared and characterized and their properties were measured and discussed with regard to effects of side chains. Incorporation of the side chains onto the rigid main chain greatly enhanced the solubility and fusibility of the polymers, and melting point of C₈-PY-PI was determined to be 277°C. The UV-VIS absorption behavior was independent of side-chain length. TGA thermograms revealed a two-step pyrolysis behavior, in which the side chains split off separately at lower temperatures. X-ray diffractograms showed that all the polyimides are crystalline at room temperature. Sharp reflections in small-angle region obviously indicated the presence of a layered crystal structure. © 1996 John Wiley & Sons, Inc.     

Synthesis and characterization of novel fused porphyrinoids based on cyclic carbazole[2]indolones

The carbazole- and indolone-based porphyrinoids 3 and 4 were synthesized by stepwise transition-metal-catalyzed coupling reactions. Palladium metalation of 4 produced 4Pd, which exhibits near-infrared absorption.     

Synthesis and characterization of new soluble cardo polyamides containing the tricyclo[5.2.1.02,6]decane group

A new cardo dicarboxylic acid, 8,8‐bis[4‐(4‐carboxyphenoxy)phenyl]tricyclo[5.2.1.0^2,6]decane (BCPTD), was synthesized from 4,4′‐(octahydro‐4,7‐methano‐5H‐inden‐5‐ylidene)bisphenol and p‐fluorobenzonitrile via aromatic nucleophilic substitution followed by hydrolysis. A series of new cardo polyamides was prepared by the direct polycondensation of BCPTD and various aromatic diamines in N‐methyl‐2‐pyrrolidinone (NMP) with triphenyl phosphite and pyridine as the condensing agents. Polymers were produced with moderate to high inherent viscosities of 0.65 to 1.08 dL g⁻¹. The polymers, except for polymer PA1 , exhibited number‐average molecular weights and weight‐average molecular weights in the range of 38,400 to 86,300 and 57,800 to 148,000, respectively. Nearly all of the polymers were readily soluble in polar solvents such as NMP, N,N‐dimethylacetamide, N,N‐dimethylformamide, and dimethyl sulfoxide as well as in less polar solvents such as pyridine, γ‐butyrolactone, and tetrahydrofuran. All of the polymers were amorphous, and the polyamide films had a tensile‐strength range of 75 to 128 MPa and a tensile‐modulus range of 2.0 to 2.8 GPa. These polyamides had glass‐transition temperatures between 240 and 269°C and 10% weight‐loss temperatures in the range of 477 to 508°C and 471 to 518°C in nitrogen and air atmospheres, respectively. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 74–79, 2000     

Synthesis and characterization of organosoluble aliphatic-aromatic copolyimides based on cycloaliphatic dianhydride

A series of aliphatic-aromatic polyimides have been synthesized. These polyimides were prepared by high-temperature polycondensation of the aliphatic diamines: 1,4-diaminobutane, 1,6-diaminohexane, 1,7-diaminoheptane, 1,9-diaminononane, 1,10-diaminodecane, 1,12-diaminododecane and 4,4^′-methylenebis(2,6-dimethylaniline) with 1,2,3,4-cyclopentanetetracarboxylic dianhydride. Various ratios of diamines (aromatic:aliphatic) have been applied for preparation of copolyimides. Polycondensation proceeded at 190 °C and produced copolyimides with reduced viscosities up to 0.92 dl/g. The polyimides were soluble in a wide range of organic, common solvents and showed high-thermal stability. In most cases these polymers formed flexible films which presented excellent transparency.     

Synthesis and characterization of novel polyimides with bulky pendant groups

New dianhydrides containing t‐butyl and phenyl pendant groups have been synthesized and used as monomers, together with commercial diamines, to prepare novel polyimides. The influence of the chemical structure of the monomers on their reactivity has been studied by quantum semiempirical methods. The polyimides have been characterized by FTIR and by NMR in the case of soluble polymers. The presence of pendant groups and the method used to imidize polyimide precursors greatly affected polymer properties such as solubility, glass transition temperature, thermal stability, and mechanical properties. As a rule, the novel polyimides showed better solubility in organic solvents than the parent polyimides. Glass transition temperatures in the range 250–270°C and decomposition temperatures over 520°C were observed for the set of current polymers. Tensile strengths up to 135 MPa and mechanical moduli up to 3.0 GPa were measured on films of the current polyimides. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 805–814, 1999     

Synthesis,characterization and memory properties of novel organosoluble polyimides

Two novel series of aromatic polyimides were prepared from 2,2′‐bis(4‐amino‐3‐trifluoromethylthylphenoxy) biphenyl, 2,2′‐bis(4‐amino‐3‐methoxyphenoxy)biphenyl with 3,3′,4,4′‐benzophenonetetracarboxylic dianhydride (BTDA), 3,3′,4,4′‐diphenylsulfonetetracarboxylic dianhydride (DSDA) via a one‐step procedure. The resulting polymers were fully characterized, and they exhibited excellent organosolubility. These polyimides are thermally stable with 5% weight loss over 430°C, and glass transition temperatures of the polyimides were found to be 225–262°C. Resistive switching devices with the configuration of Al/polymer/indium‐tin oxide were constructed from these polyimides by using conventional solution coating process. Devices with all polyimides exhibited nonvolatile and rewritable flash type memory characteristics with turn‐on voltage at ?1.1 to ?2.8 V. The ON/OFF current ratio of these devices was larger than 10⁴, and the retention times can be as long as 10⁴ s. The theoretical simulation based on the density functional theory suggested that greater distinct charge separation between the ground and charge transfer states led to a highly stable memory behavior. Copyright © 2016 John Wiley & Sons, Ltd.     

Synthesis and characterization of spirobifluorene‐based polyimides

The synthesis and properties of organosoluble aromatic polyimides, containing spiro‐skeletal units in the polymer backbone on the basis of the spiro‐diamine monomer, 2,2′‐diamino‐9,9′‐spirobifluorene, are described. In the case of the spiro segment, the two fluorene rings are orthogonally arranged and connected through a tetrahedral bonding carbon atom, the spiro center. As a consequence, the polymer chain is periodically zigzagged with a 90° angle at each spiro center. This structural feature minimizes interchain interactions and restricts the close packing of the polymer chains, resulting in amorphous polyimides that have good solubility in organic solvents. Compared with their fluorene‐based cardo analogues, the spirobifluorene‐based polyimides have an improved solubility. Furthermore, the main‐chain rigidity of the polyimide appears to be preserved because of the presence of the spiro structure, which restricts the free segmental mobility. As a result, these polyimides exhibit a high glass‐transition temperature (T_g's) and good thermal stability. The T_g's of these polyimides were in the range of 287–374 °C, and the decomposition temperatures in nitrogen for a 10% weight loss occurred at temperatures above 570 °C. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3615–3621, 2002     

Synthesis and characterization of new polyimides containing calix[4]arenes in the polymer backbone

Two diaminocalix[4]arene monomers were synthesized from p-tert-butylcalix[4]arene through a 4-step reaction sequence. New copoly(amic acid)s containing calix[4]arene moieties on the polymer backbone were successfully synthesized in N-methyl-2-pyrrolidone by polycondensations of 4,4′-oxydiphthalic anhydride (ODPA) with the diaminocalix[4]arene monomers using 4,4′-oxydiphenylene diamine (ODA) as a comonomer. These copoly(amic acid)s were soluble in aprotic polar solvents, so that they can be processed in various ways. The copoly(amic acid) precursors were thermally converted to the corresponding copolyimides in films. The copolyimide films are amorphous, but insoluble in common solvents. They are thermally stable up to 366°C. The copolyimides exhibit relatively high TEC's, low T_g's, low refractive index, low dielectric constant, low optical anisotropy, low dielectric anisotropy, and low water uptake, compared to those of conventional ODPA-ODA polyimide. These property characteristics were interpreted in regard to bulky, cone-like calix[4]arene moieties and their effects on the chain conformation and morphological structure. The processability and property characteristics support that both of the copolyimides containing calix[4]arene moieties are potential candidate materials suitable for membranes, antioxidant additives, chemical sensor devices, and microelectronic devices. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 2013–2026, 1999     

Synthesis and characterization of novel calix[6]phyrin derivatives

Three novel calix[6]phyrin derivatives have been synthesized by reaction of corresponding tripyrrane with aromatic aldehyde. The reaction condition was optimized and the structures of these compounds have been characterized by NMR and MS.     

Synthesis, structural characterization, and skeletal rearrangement of dibenzo tricyclo[3.3.0.0]-1,2,5,6-tetrasubstituted octanes

Dibenzo tricyclo[3.3.0.0^2,6]-1,2,5,6-tetrasubstituted octanes, the ‘twisted’ highly strained valence isomers of substituted dibenzo[a,e]cyclooctatetraenes, were synthesized and their structure characterized by single-crystal X-ray analysis. Their skeletal rearrangement was experimentally observed.     

Synthesis and characterization of fluorinated polyimides derived from novel unsymmetrical diamines

Two kinds of aromatic, unsymmetrical diamines with ether-ketone group, 3-amino-4′-(4-amino-2-trifluoromethylphenoxy)-benzophenone and 4-amino-4′-(4-amino-2-trifluoromethylphenoxy)-benzophenone, were successfully synthesized with two different synthetic routes. Then, they were polymerized with 4,4′-oxydiphthalic anhydride, 3,3′,4,4′-benzophenone tetracarboxylic dianhydride, and 2,2′-bis(3,4-dicarboxyphenyl)-hexafluoropropane dianhydride to form a series of fluorinated polyimides via a conventional two-step thermal or chemical imidization method. The resulting polyimides were characterized by measuring their solubility, viscosity, mechanical properties, IR-FT, and thermal analysis. The results showed that the polyimides had inherent viscosities of 0.48-0.68 dl/g and were easily dissolved in bipolarity solvents and common, low-boiling point solvents. Meanwhile, the resulting strong and flexible polyimide films exhibited excellent thermal stability, e.g., decomposition temperatures (at 10% weight loss) are above 575 °C and glass-transition temperatures in the range of 218-242 °C. The polymer films also showed outstanding mechanical properties, such as tensile strengths of 86.5-132.8 MPa, elongations at break of 8-14%, and initial moduli of 1.32-1.97 GPa. These outstanding combined features ensure that the polymers are desirable candidate materials for advanced applications.     

Density functional study of tricyclo[3,3,1,13,7]decane and tricyclo[3,3,1,13,7]decsilane and their halogen derivatives

The B3LYP/3‐21G* ab initio molecular orbital method from the Gaussian 94 computer program package was applied to study tricyclo[3,3,1,1^3,7]decane and tricyclo[3,3,1,1^3,7]decsilane molecules and their halogen derivatives (1,3,5,7‐tetrahalotricyclo[3,3,1,1^3,7]decane and 1,3,5,7‐tetrahalotricyclo[3,3,1,1^3,7]decsilane, C₁₀H₁₂X₄, and Si₁₀H₁₂X₄). The optimized structures of these compounds were obtained. Ionization potentials, HOMO and LUMO energies, energy gaps, heats of formation, atomization energies, and vibration frequencies were calculated. These calculations indicate that these molecules are stable and have T_d symmetry. Tricyclo[3,3,1,1^3,7]decsilane and its halogen derivatives (Si₁₀H₁₂X₄) are found to have higher conductivity than that of tricyclo[3,3,1,1^3,7]decane and its halogen derivatives (C₁₀H₁₂X₄). 1,3,5,7‐Tetraflourotricyclo[3,3,1,1^3,7]decane (C₁₀H₁₂F₄) and 1,3,5,7‐tetraflourotricyclo[3,3,1,1^3,7]decsilane (Si₁₀H₁₂F₄) were found to be the easiest compounds to form and the most difficult to dissociate of all 1,3,5,7‐tetrahalotricyclo[3,3,1,1^3,7]decane and 1,3,5,7‐tetrahalotricyclo[3,3,1,1^3,7]decsilane compounds, respectively. ©1999 John Wiley & Sons, Inc. Int J Quant Chem 72: 189–198, 1999