Electroactive aromatic polyamides and polyimides with adamantylphenoxy-substituted triphenylamine units

A new triphenylamine-containing aromatic diamine monomer, 4-[4-(1-adamantyl)phenoxy]-4′,4″-diaminotriphenylamine, was synthesized from cesium fluoride-mediated N,N-diarylation of 4-(1-adamantyl)-4′-aminodiphenyl ether with 4-fluoronitrobenzene and subsequent reduction of the resultant dinitro compound. Novel electroactive aromatic polyamides and polyimides with adamantylphenoxy-substituted triphenylamine moieties were prepared from the newly synthesized diamine monomer with aromatic dicarboxylic acids and tetracarboxylic dianhydrides, respectively. All the resulting polymers were amorphous and most of them were readily soluble in polar solvents such as N-methyl-2-pyrrolidone (NMP) and N,N-dimethylacetamide (DMAc) and could be solution-cast into transparent and strong films with good mechanical properties. These polymers exhibited glass-transition temperatures between 254 and 310 °C, and they were fairly stable up to a temperature above 450 °C for the polyamides and above 500 °C for the polyimides. These polymers exhibited strong UV-vis absorption maxima at 293-346 nm in solution, and the photoluminescence spectra of polyamides showed maximum bands around 408-452 nm in the blue region. Cyclic voltammograms of the polyamide and polyimide films on an indium-tin oxide (ITO)-coated glass substrate exhibited one pair of reversible redox couples at half-wave oxidation potentials (E_1/2) around 0.83-0.86 V and 1.12-1.13 V, respectively, versus Ag/AgCl in an acetonitrile solution. All the polymer films revealed good electrochemical and electrochromic stability by repeatedly switching electrode voltages between 0.0 V and 1.1-1.4 V, with coloration change from the pale yellowish neutral state to the green or blue oxidized state.     

Synthesis and characterization of polyamides containing pendant pentadecyl chains

A new aromatic diacid monomer viz., 4-(4′-carboxyphenoxy)-2-pentadecylbenzoic acid was synthesized starting from cardanol and was characterized by FTIR, ¹H- and ¹³C NMR spectroscopy. A series of new aromatic polyamides containing ether linkages and pendant pentadecyl chains was prepared by phosphorylation polycondensation of 4-(4′-carboxyphenoxy)-2-pentadecylbenzoic acid with five commercially available aromatic diamines viz., 1,4-phenylenediamine, 4,4′-oxydianiline, 4,4′-methylenedianiline, 1,3-phenylenediamine, and 4,4′-(hexafluoroisopropylidene)dianiline. Inherent viscosities of the polyamides were in the range 0.45-0.66 dL/g in N,N-dimethylacetamide at 30 ± 0.1 °C. The introduction of ether linkages and pendant pentadecyl chains into polyamides led to an enhanced solubility in N,N-dimethylacetamide and 1-methyl-2-pyrrolidinone at room temperature or upon heating. The polyamides could be solution-cast into tough, flexible and transparent films from their N,N-dimethylacetamide solution. Wide angle X-ray diffraction patterns exhibited broad halo indicating that the polymers were essentially amorphous in nature. X-Ray diffractograms also displayed a diffuse to sharp reflection in the small-angle region (2θ = ∼2-5°) for the polyamides characteristics of formation of loosely to well-developed layered structure arising from packing of flexible pentadecyl chains. The glass transition temperature observed for the polyamides was in range 139-189 °C. The temperature at 10% weight loss (T₁₀), determined by TGA in nitrogen atmosphere, of the polyamides was in the range 425-453 °C indicating their good thermal stability.     

Aromatic polyamides with pendent acetoxybenzamide groups and thin films made therefrom

New aromatic polyamides containing 1,3,4-oxadiazole or benzonitrile units in the main chain and 5-(4-acetoxybenzamido) groups in the side chain have been synthesized and their properties have been characterized and compared with those of related polyamides and polyoxadiazole-amides. These polymers show good thermal stability, with initial decomposition temperature being at about 300 °C and glass transition temperature in the range of 260-280 °C. They are easily soluble in certain solvents such as N-methylpyrrolidinone (NMP), N,N^′-dimethylacetamide (DMA) and N,N^′-dimethylformamide (DMF) and can be cast from solutions into thin flexible films. The polymer films had tensile strengths in the range of 77-97 MPa, tensile moduli in the range of 2.3-2.6 GPa and elongation at break values ranging from 6% to 24%. One of the polymers containing the 1,3,4-oxadiazole ring exhibited blue fluorescence.     

Novel thermally stable and chiral poly(amide-imide)s bearing from N,N′-(4,4′-diphthaloyl)-bis-l-isoleucine diacid: Synthesis and characterization

Novel optically active aromatic poly(amide-imide)s (PAIs) were prepared from newly synthesized N,N′-(4,4′-diphthaloyl)-bis-l-isoleucine diacid (3) via polycondensation with various diamines. The diacid was synthesized by the condensation reaction of 3,3′,4,4′-biphenyltetracarboxylic dianhydride (1) with l-isoleucine (2) in a mixture of acetic acid and pyridine (3:2 v/v). All the polymers were obtained in quantitative yields with inherent viscosities of 0.20-0.43 dL g⁻¹. All the polymers were highly organosoluble in solvents like N-methyl-2-pyrrolidinone (NMP), N,N-dimethylacetamide (DMAc), N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), tetrahydrofuran, γ-butyrolactone, cyclohexanone and chloroform at room temperature or upon heating. These poly(amide-imide)s had glass transition temperatures between 198 and 231 °C, and their 10% weight-loss temperatures were ranging from 368 to 398 °C and 353 to 375 °C under nitrogen and air, respectively. The polyimide films had tensile strengths in the range of 63-88 MPa and tensile moduli in the range of 0.8-1.4 GPa. These poly(amide-imide)s possessed chiral properties and the specific rotations were in the range of −3.10° to −72.92°.     

Microwave-assisted clean synthesis of aromatic photoactive polyamides derived from 5-(3-acetoxynaphthoylamino)-isophthalic acid and aromatic diamines in ionic liquid

Dicarboxylic acid, 5-(3-acetoxynaphthoylamino)isophthalic acid was prepared in three steps. The direct polycondensation of this novel diacid with several aromatic diamines was studied in 1,3-diisopropylimidazolium bromide as an ionic liquid (IL) under microwave irradiation and conventional heating. The polymerization reaction was effectively preceded in IL, and triphenyl phosphite as an activating agent, and the resulting novel photoactive polyamides were obtained in high yields and moderate inherent viscosities in the range of 0.44-0.69 dL/g. Thermogravimetric analysis showed that polymers are thermally stable, 10% weight loss temperatures in excess of 390 and 470 °C, and char yields at 600 °C in nitrogen higher than 60%. These macromolecules exhibited maximum UV-vis absorption at 265 and 300 nm in N,N-dimethylformamide (DMF) solution. Their photoluminescence in DMF solution demonstrated fluorescence emission maxima around 361 and 427 nm for all of the polyamides. It is very important to note that, because of, high polarizability of ILs, they are very good solvents for absorbing microwaves.     

Electrochemical and electrochromic properties of novel aromatic poly(amine-amide)s derived from N,N′-bis(4-carboxyphenyl)-N,N′-diphenyl-1,4-phenylenediamine

A series of novel triphenylamine-containing aromatic poly(amine-amide)s were prepared from the dicarboxylic acid, N,N′-bis(4-carboxyphenyl)-N,N′-diphenyl-1,4-phenylenediamine, and various diamines by direct phosphorylation polycondensation. All the poly(amine-amide)s were amorphous, soluble in a variety of organic solvents, and could be solution cast into transparent, tough, and flexible films with good mechanical properties. They had useful levels of thermal stability associated with relatively high glass-transition temperatures (195-280 °C). These polymers exhibited strong UV-Vis absorption bands at 330-346 nm and their photoluminescence showed maximum bands around 516-535 nm in NMP solution. The hole-transporting and electrochromic properties are examined by electrochemical and spectroelectrochemical methods. Cyclic voltammograms of the poly(amine-amide)s prepared by casting polymer solution onto an indium-tin oxide (ITO)-coated glass substrate exhibited two reversible oxidative redox couples at potential 0.73-0.78 V and 1.12-1.18 V, respectively vs Ag/AgCl in acetonitrile solution. All the poly(amine-amide)s exhibited excellent reversibility of electrochromic characteristics by continuous ten cyclic scans between 0.0 and 1.40 V, with a color change from original pale yellowish neutral form to the green and then to blue oxidized forms.     

Synthesis, characterization and constitutional isomerism study of new aromatic polyamides containing pendant groups based on asymmetrically substituted meta-phenylene diamines

Four new aromatic polyamides containing pendant groups were synthesized by low temperature interfacial polycondensation of two asymmetrically substituted diamine monomers, namely, 4-[4-(1-methyl-1-phenylethyl) phenoxy]-1,3-diamino benzene and 4-{4-[(4-methylphenyl) sulphonyl]phenoxy}-1,3-diamino benzene with two aromatic diacid chlorides, namely isophthaloyl chloride and terephthaloyl chloride. Inherent viscosities of polyamides were in the range 0.64-0.72 dL/g indicating formation of medium molecular weight polymers. The weight average molecular weights and number average molecular weights, determined by gel permeation chromatography (polystyrene standard), were in the range 54,500-65,000 and 19,750-27,000, respectively. The constitutional isomerism of synthesized polyamides was investigated by ¹H and ¹³C NMR spectroscopy, where as the constitutional order was calculated from ¹H NMR spectroscopy and was found to be in the range 0.35-0.37. Polyamides containing pendant groups were essentially amorphous and were soluble in polar aprotic solvents such as N, N-dimethyl acetamide, N-methyl-2-pyrrolidone, N, N-dimethyl formamide and dimethyl sulfoxide. Polyamides exhibited glass-transition temperature in the range 237-254 °C. The initial decomposition temperature, determined by TGA in nitrogen atmosphere, of polyamides was in the range 371-410 °C indicating their good thermal stability.     

New soluble aromatic polyamides containing ether linkages and laterally attached p-terphenyls

Two series of new polyamides containing flexible ether linkages and laterally attached side rods (3a-i and 4a-i) were synthesized from 2^′,5^′-bis(4-aminophenoxy)-[1,1^′;4^′,1^″]terphenyl (1a) and 2^′,5^′-bis(4-amino-2-trifluoromethylphenoxy)-[1,1^′;4^′,1^″]terphenyl (1b), respectively, with various aromatic dicarboxylic acids by the direct phosphorylation polycondensation. The polymers were produced with high yields and moderate to high inherent viscosities (0.41-0.97 dl/g) that corresponded to weight-average molecular weights (by size exclusion chromatography) of 47,000-65,000. Except for some polyamides that derived from rigid diacids, the obtained polyamides were readily soluble in aprotic polar solvents, such as N-methyl-2-pyrrolidone (NMP) and N,N-dimethylacetamide (DMAc), and could afford flexible and tough films via solvent casting. The polymer films cast from DMAc solutions possessed tensile strengths of 85-106 MPa and initial moduli of 1.82-2.96 GPa. These polyamides showed glass-transition temperatures (T_g) in the range of 206-263 °C (by DSC) and softening temperatures (T_s) in the range of 211-253 °C (by TMA). Decomposition temperatures (T_d) for 10% weight loss all occurred above 400 °C (by TGA) in both nitrogen and air atmospheres. The polyamides 4a-i derived from trifluoromethyl-substituted diamine 1b generally showed a higher solubility, T_g and T_s but lower thermal stability as compared to the analogous polyamides 3a-i based on diamine 1a.     

Synthesis and characterization of new aromatic poly(ether imide)s and their gas transport properties

A series of processable fluorinated poly(ether imide)s (PIs) were synthesized by reacting a diamine monomer, 1,4-bis-[{2′-trifluromethyl 4′-(4″-aminophenyl)phenoxy}] benzene (HQA) with six different aromatic dianhydrides e.g., BPADA, 6FDA, ODPA, BPDA, BTDA and PMDA. The polyimides showed reasonably high glass-transition temperature (T_g up to 280 °C) and high thermal stability (T_d,10 up to 558 °C). The membranes of these polymers showed tensile strength up to 107 MPa with elongation at break up to 15%, low water absorption (0.61–1.29%), low dielectric constant (2.10–3.13 at 1 MHz) and high optical transparency (λ_cut-off up to 466 nm). The PI membrane prepared from 6FDA exhibited high permeability and permselectivity for O₂/N₂ (P_O2 = 11.8 and P_O2/P_N2 = 9.44) gas pair which eventually surpassed the present upper boundary limit drawn by L.M. Robeson.     

Soluble and thermally stable polyamides bearing 1,1′-thiobis(2-naphthoxy) groups

A new-type of sulfide containing diacid (1,1′-thiobis(2-naphthoxy acetic acid)) was synthesized from 2-naphthol in three steps. Reaction of 2-naphthol with sulfur dichloride afforded 1,1′-thiobis(2-naphthol) (TBN). 1,1′-Thiobis(2-naphthoxy acetic ester) (TBNAE) was successfully synthesized by refluxing the TBN with methylcholoroacetate in the presence of potassium carbonate. The related diacid was synthesized by basic solution reduction of TBNAE. The obtained diacid was fully characterized and used to prepare novel thermally stable poly(sulfide ether amide)s via polyphosphorylation reaction with different aromatic diamines. The properties of these new polyamides were investigated and compared with similar polyamides. These polyamides showed inherent viscosities in the range of 0.39-0.87 dL g⁻¹ in N,N-dimethylacetamide (DMAc) at 30 °C and at a concentration of 0.5 g dL⁻¹. All the polyamides were readily soluble in a variety of polar solvents such as DMAc and tetrahydrofuran (THF). These polyamides showed glass transition temperature (T_g) between 241-268 °C. Thermogravimetric analysis measurement revealed the decomposition temperature at 10% weight loss (T₁₀) ranging from 441- 479 °C in argon atmosphere.     

A novel class of organosoluble and light-colored fluorinated polyamides derived from 2,2-bis(4-amino-2-trifluoromethylphenoxy)biphenyl or 2,2-bis(4-amino-2-trifluoromethylphenoxy)-1,1-binaphthyl

Two series of novel fluorinated aromatic polyamides were prepared from 2,2^′-bis(4-amino-2-trifluoromethylphenoxy)biphenyl (2) and 2,2^′-bis(4-amino-2-trifluoromethylphenoxy)-1,1^′-binaphthyl (4) with various aromatic dicarboxylic acids using the phosphorylation polycondensation technique. The polyamides had inherent viscosities ranging from 0.43 to 0.62 dl/g and 0.36 to 0.74 dl/g, respectively. All the fluorinated polyamides were soluble in many polar organic solvents such as N,N-dimethylacetamide (DMAc), N-methyl-2-pyrrolidinone, and afforded transparent, light-colored, and flexible films upon casting from DMAc solvent. These polyamides showed glass-transition temperatures in the ranges of 190-240 °C (for the 6 series from diamine 2) and 247-255 °C (for the 7 series from diamine 4) by differential scanning calorimetry, softening temperatures in the ranges of 196-230 °C (6 series) and 241-291 °C (7 series) by thermomechanical analysis, and decomposition temperatures for 10% weight loss above 420 °C in both nitrogen and air atmospheres.     

Synthesis and characterization of new aromatic polyesters containing cardo decahydronaphthalene groups

Three cardo bisphenols containing decahydronaphthalene group viz., 4,4′-(octahydro-2(1H)-naphthylidene)bisphenol, 4,4′-(octahydro-2(1H)-naphthylidene)bis-3-methylphenol and 4,4′-(octahydro-2(1H)-naphthylidene)bis-3,5-dimethylphenol were synthesized starting from commercially available 2-naphthol and were utilized for synthesis of new aromatic polyesters by phase transfer-catalyzed interfacial polycondensation with isophthaloyl chloride, terephthaloyl chloride and a mixture of isophthaloyl chloride and terephthaloyl chloride (50:50 mol %). Inherent viscosities and number average molecular weights (M_n) of polyesters were in the range 0.35-0.84 dL/g and 13,300-48,500 (Gel Permeation Chromatography, polystyrene standard), respectively. Polyesters were readily soluble in organic solvents such as dichloromethane, chloroform, tetrahydrofuran, meta-cresol, pyridine, N,N-dimethylformamide, N,N-dimethylacetamide, and 1-methyl-2-pyrrolidinone at room temperature and could be cast into tough, transparent and flexible films from their chloroform solutions. Wide-angle X-ray diffraction measurements revealed the amorphous nature of polyesters. The glass transition temperature of polyesters was in the range 207-287 °C. The temperature at 10% weight loss (T₁₀), determined from thermogravimetric analysis of polyesters, was in the range 425-460 °C indicating their good thermal stability.     

Synthesis and characterization of new polyimides containing pendent pentadecyl chains

A new unsymmetrical aromatic diamine, viz., 4-pentadecylbenzene-1,3-diamine was synthesized through a series of reaction steps starting from 3-pentadecylphenol. 4-Pentadecylbenzene-1,3-diamine was employed to synthesize a series of new polyimides by one-step polycondensation in m-cresol with four commercially available aromatic dianhydrides, viz., 3,3′,4,4′-biphenyltetracarboxylic dianhydride (BPDA), 3,3′,4,4′-benzophenonetetracarboxylic dianhydride (BTDA), 4,4′-oxydiphthalic anhydride (ODPA) and 4,4′-(hexafluoroisopropylidene)diphthalic anhydride (6-FDA). Inherent viscosities of resulting polyimides were in the range 0.33-0.67 dL/g and number average molecular weights were in the range 14,700-52,200 (GPC, polystyrene standard). Polyimides containing pendent pentadecyl chains were soluble in organic solvents such as chloroform, m-cresol, N,N-dimethylacetamide (DMAc), 1-methyl-2-pyrrolidinone (NMP), pyridine and nitrobenzene. Strong and flexible films of polyimides could be cast from their chloroform solutions. Polyimides exhibited glass transition temperature in the range 158-206 °C. The temperature at 10% wt. loss (T₁₀), determined by TGA in nitrogen atmosphere, of polyimides was in the range 470-480 °C indicating good thermal stability.     

Naphthalene-ring containing diamine and resulting thermally stable polyamides

A new naphthalene-ring containing diamine, bis-[4-(5-amino-naphthalene-1-yloxy)-phenyl]-methanone was prepared from reaction of 5-amino-1-naphthol with 4,4′-dichlorobenzophenone in the presence of K₂CO₃. A series of novel polyamides were prepared by direct polycondensation of the diamine with various commercially available diacid chlorides including terephthaloyl chloride, isophthaloyl chloride, adipoyl chloride, and sebacoyl chloride. All the synthesized polyamides showed good solubility in amide type solvents such as N-methyl-2-pyrrolidone, N,N-dimethylacetamide, and N,N-dimethylformamide and they exhibited inherent viscosities in the range of 0.44-0.52 dL/g. According to the DMTA analysis, the glass transition temperatures of the polyamides were found to be 131-187 °C. Thermogravimetric analysis indicated that the polymers were stable up to 190 °C and the 10% weight loss temperatures were recorded in the range of 350-418 °C in air atmosphere.     

High glass transitions of novel organosoluble polyamide-imides based on noncoplanar and rigid diimide-dicarboxylic acid

A series of novel polyamide-imides (PAIs) with high glass transition temperature were prepared from diimide-dicarboxylic acid, 2,2′-bis(trifluoromethyl)-4,4′-bis(trimellitimidophenyl)biphenyl (BTFTB), by direct polycondensation with various diamines in N-methyl-2-pyrrolidinone using triphenyl phosphite and pyridine as condensing agents in the presence of dehydrating agent (CaCl₂). The yield of the polymers was obtained was high with moderate to high inherent viscosities (0.80-1.03 dL g⁻¹). Gel permeation chromatography (GPC) of the polymers showed number-average and weight-average molecular weights up to 8.6 × 10⁴ and 22 × 10⁴, respectively. The PAIs were amorphous in nature. Most of the polymers exhibited good solubility in various solvents such as N-methyl-2-pyrrolidinone (NMP), N,N-dimethylacetamide (DMAc), N,N-dimethylformamide (DMF), pyridine, cyclohexanone and tetrahydrofuran. The polymer films had tensile strength in the range of 79-103 MPa, an elongation at break in the range of 6-16%, and a tensile modulus in the range between 2.1 and 2.8 GPa. The glass transition temperatures of the polymers were determined by DMA method and they were in the range of 264-291 °C. The coefficients of thermal expansion (CTE) of PAIs were determined by TMA instrument and they were between 29 and 67 ppm °C⁻¹. These polymers were fairly thermally stable up to or above 438 °C, and lose 10% weight in the range of 446-505 °C and 438-496 °C, respectively, in nitrogen and air. These polymers had exhibited 80% transmission wavelengths which were in the range of 484-516 nm and their cutoff wavelengths were in between 418 and 434 nm. The PAIs with trifluoromethyl group have higher bulk density resulting in higher free volume and then lowering the dielectric constant.     

Synthesis and characterization of poly(amideimide)s containing pendent flexible alkoxy chains

A series of aromatic diacylhydrazides containing pendent flexible alkoxy chains, viz., 5-butyloxyisophthalicacid dihydrazide, 5-octyloxyisophthalicacid dihydrazide, 5-dodecyloxyisophthalicacid dihydrazide and 5-hexadecyloxyisophthalicacid dihydrazide were synthesized by the hydrazinolysis reaction of the corresponding aromatic esters with hydrazine hydrate. Diacylhydrazides were each polycondensed with aromatic dianhydrides, viz., 4,4′-oxydiphthalic anhydride (ODPA), 3,3′,4,4′-biphenyltetracarboxylic dianhydride (BPDA) and pyromellitic dianhydride (PMDA) to obtain new poly(amideimide)s. Poly(amideimide)s had inherent viscosity in the range 0.55-0.88 dL/g in N,N-dimethylacetamide (DMAc) at 30 ± 0.1 °C. Poly(amideimide)s were found to be soluble in DMAc, N,N-dimethylformamide (DMF), 1-methyl-2-pyrrolidinone (NMP) and pyridine and could be cast into tough, flexible and transparent films from a solution in DMAc. X-ray diffractograms revealed that poly(amideimide)s with longer alkoxy chains had layered structures. Glass transition temperature of poly(amideimide)s containing pendent flexible alkoxy chains were in the range 215-245 °C. Temperature at 10% weight loss was in the range 380-410 °C in nitrogen atmosphere indicating good thermal stability of poly(amideimide)s.     

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 soluble polyimides based on a new fluorinated diamine: 4-Phenyl-2,6-bis[3-(4′-amino-2′-trifluoromethyl-phenoxy) phenyl] pyridine

A new kind of pyridine-containing aromatic diamine monomer, 4-phenyl-2,6-bis[3-(4′-amino-2′-trifluoromethyl-phenoxy) phenyl] pyridine (m-PAFP), was successfully synthesized by a modified Chichibabin reaction of 3-(4′-nitro-2′-trifluoro-methyl-phenoxy)-acetophenone with benzaldehyde, followed by a catalytic reduction. A series of fluorinated pyridine-bridged aromatic poly(ether-imide)s were prepared from the resulting diamine monomer with various aromatic dianhydrides via a conventional two-step thermal or chemical imidization method. The inherent viscosities values of these polyimides were in the range of 0.56-1.02 dL/g, and they could be cast and thermally converted into transparent, flexible, and tough polyimide films. The polyimides displayed higher solubility in polar solvents such as NMP, DMSO and m-cresol. The polyimides had good thermal stability, with the glass transition temperatures (T_g) of 187-211 °C, the temperatures at 5% weight loss of 511-532 °C, and the residue at 800 °C in air was higher than 50%. These films also had dielectric constants of 2.64-2.74 at 10 MHz and low water uptake 0.53-0.66%. Wide-angle X-ray diffraction measurements revealed that these polyimides were predominantly amorphous. Moreover, the polymer films of these novel polyimides showed outstanding mechanical properties with the tensile strengths of 90.1-96.6 MPa, elongations at breakage of 8.9-10.7% and tensile modulus of 1.65-1.98 GPa.     

Regularly alternating poly(amideimide)s containing pendent pentadecyl chains: Synthesis and characterization

Two new aromatic diamines containing preformed amide linkages, viz., N,N′-(4-pentadecyl-1,3-phenylene)bis(4-aminobenzamide) I and N,N′-(4-pentadecyl-1,3-phenylene)bis(3-aminobenzamide) II, were synthesized by reaction of 4-pentadecylbenzene-1,3-diamine with 4-nitrobenzoylchloride and 3-nitrobenzoylchloride, followed by reduction of the respective dinitro derivatives. A series of new poly(amideimide)s was synthesized by polycondensation of I and II with four commercially available aromatic dianhydrides, viz., pyromellitic dianhydride (PMDA), 4,4′-biphenyltetracarboxylic dianhydride (BPDA), 4,4′-oxydiphthalic anhydride (ODPA), and 4,4′-(hexafluoroisopropylidene)diphthalic anhydride (6-FDA) in N,N-dimethylacetamide (DMAc) employing conventional two step method via poly(amic acid) intermediate followed by thermal imidization. Reference poly(amideimide)s were synthesized by polycondensation of N,N′-(1,3-phenylene)bis(4-aminobenzamide) and N,N′-(1,3-phenylene)bis(3-aminobenzamide) with the same aromatic dianhydrides. Inherent viscosities of poly(amideimide)s containing pendent pentadecyl chains were in the range 0.37-1.23 dL/g in N,N-dimethylacetamide at 30 ± 0.1 °C indicating the formation of medium to high molecular weight polymers. The poly(amideimide)s containing pendent pentadecyl chains were found to be soluble in N,N-dimethylacetamide, N,N-dimethylformamide, 1-methyl-2-pyrrolidinone and pyridine and could be cast into transparent, flexible and tough films from their N,N-dimethylacetamide solution. Wide angle X-ray diffraction patterns exhibited broad halo indicating that the polymers were essentially amorphous in nature. X-ray diffractograms also displayed sharp reflection in the small angle region (2θ ≈ 3°) for poly(amideimide)s containing pentadecyl chains indicating the formation of layered structure arising from packing of flexible pentadecyl chains. The glass transition temperatures observed for reference poly(amideimide)s were in the range 331-275 °C and those for poly(amideimide)s containing pendent pentadecyl chains were in the range 185-286 °C indicating a large drop in T_g owing to the “internal plasticization” effect of pentadecyl chains. The temperature at 10% weight loss (T₁₀), determined by TGA in nitrogen atmosphere, were in the range 460-480 °C indicating their good thermal stability.     

Electrochromic properties of novel strictly alternating poly(amine-amide-imide)s with electroactive triphenylamine moieties

A series of novel triphenylamine-containing aromatic poly(amine-amide-imide)s (PAAIs) were prepared by the phosphorylation polyamidation reactions from the diamine, N,N′-bis(4-aminophenyl)-N,N′-diphenyl-1,4-phenylenediamine, and various imide ring-preformed dicarboxylic acids. All the PAAIs were amorphous, had good solubility in many polar aprotic solvents, and exhibited excellent thin film forming capability with good mechanical properties. They displayed relatively high glass-transition temperatures (220-306 °C) and good thermal stability, with 10% weight-loss temperatures in excess of 522 °C in air or nitrogen and char yields at 800 °C in nitrogen higher than 66%. The solutions of polymers in NMP exhibited strong UV-vis absorption bands with a maximum around 315 nm. The hole-transporting and electrochromic properties were examined by electrochemical and spectroelectrochemical methods. Cyclic voltammograms of the PAAIs prepared by casting polymer solution onto an indium-tin oxide (ITO)-coated glass substrate exhibited two reversible oxidation redox couples at 0.63 and 1.01 V vs. Ag/AgCl in acetonitrile solution. All the PAAIs revealed very stable electrochromic characteristics, changing color from original pale brownish to green, and then to blue at 0.67 and 1.08 V, respectively.