Preparation and properties of polyamides containing p-terphenyl units

Novel polyamides that contained p-terphenyl units were prepared with inherent viscosities in the range of 0.4–1.7 dL/g by the polycondensation of 4,4″-dichloroformyl-p-terphenyl with aromatic diamines and 4,4″-diamino-p-terphenyl with aromatic dicarbonyl chlorides. Polyamides composed of only paraoriented phenylene units were insoluble in all solvents and showed a high degree of crystallinity. A series of polyamides that contained p-terphenyl units were more thermostable than corresponding polymers with p-phenylene or biphenylene linkages.     

Preparation and properties of polyamides containing thianthrene units

New polyamides containing thianthrene tetraoxide were synthesized from 2,7-dichloroformylthianthrene-5,5′,10,10′-tetraoxide (A) and various diamines by the low temperature solution polycondensation technique. The resulting polyamides were characterized by i.r. and ¹H-NMR spectra and elemental analysis. The polyamides had inherent viscosities of 0.56–1.21 dl/g in DMA at 30°. All the polymers dissolved readily at room temperature in polar aprotic solvents. Density, crystallinity and thermal stability of these polyamides have been determined. In order to characterize the polymers, a model compound was also prepared from A and p-toluidine.     

Preparation and properties of polyamides and polyimides containing phenoxathiin units

Novel polyimides and polyimides having phenoxathiin units have been prepared. Polyamides with inherent viscosities in the range of 0.5–2.9 were readily prepared by the polycondensations of phenoxathiin diamines with aromatic diacyl chlorides and of aromatic diamines with new phenoxathiin diacyl chlorides. The polyimides were synthesized from phenoxathiin diamines and pyromellitic dianhydride by using a two-step procedure. The polyamic acids which formed in the first step had inherent viscosities ranging from 1.0 to 1.6, and they were converted to the polyimides by thermal cyclodehydration. Some of the phenoxanthiin-containing polyamides were highly soluble in polar amide solvents and dimethyl sulfoxide. A series of novel polymers containing phenoxathiin units were much more thermostable than the corresponding polymers having open-chain diphenyl ether linkages.     

Preparation and properties of silicon containing copolyamides

Copolyamides containing siloxane moieties in main chain were prepared by a melt polycondensation with 1,3-bis(3-aminopropyl)tetramethyldisiloxane (E), hexamethylenediamine (N6), and adipic acid (6). Glass transition temperature (T_g), cold crystallization temperature (T_cc), and melting temperature (T_m) were measured by differential thermal analysis (DTA). The depression of T_m for copolyamide was fitted by the Flory curve. Melting peak remarkably broadens with increasing E6 component in copolyamide. The change of T_g was fitted by the Gibbs and Dimarzio's equation in which the number of flexible bond is considered. The difference between T_g and T_cc increased with increasing E6 component. These DTA studies suggest that the crystallization of N66 component in copolyamide is hindered by the bulky siloxane moiety, while the micro-Brownian motion of amorphous segment is promoted by the flexible siloxane bond. Tensile strength and Young's modulus decreased with increasing E6 component. The solubility in various solvents increased with increasing E6 component. Permeability of oxygen and nitrogen increased with an increase of temperature and E6 component. The separation coefficient of oxygen to nitrogen rapidly increased near 50 mol% of E6 concentration and then leveled out above 70 mol%. The contact angle with water and methylene iodide increased with an introduction of the siloxane moiety into polymer chain.     

Synthesis and thermal properties of soluble silicon containing phenylated aromatic–aliphatic polyamides

Journal of Thermal Analysis and Calorimetry - Aromatic polyamides find many applications in diverse and critical areas due to their high thermal stability coupled with high mechanical properties....     

Synthesis and properties of polyamides containing imidazoline rings

The novel polyamide containing an imidazoline ring(PAI) was synthesized by a two-stage melt polymerization of dimethyl terephthalate (DMT) with diethylenetriamine (DETA) or triethylenetetramine (TETA). The heat resistance of PAI was superior to that of polyamide which was synthesized only in the first-stage reaction and didn't contain imidazoline ring. Their chemical structures were identified by infrared spectroscopy and NMR. The optimum condition for production was studied by varying several reaction factors, including the contents of H₂O and H₃PO₄, the reaction temperature and the reaction time at second-stage reaction under vacuum. According to study of the characteristics of solution behavior of PAI, both the viscosity and the degree of cyclization could be described by equation of in m-cresol at 30°C.     

Preparation and properties of polyamides and polymides containing bibenzyl,stilbene, and tolan structures

Polyisophthalamides and polyterephthalamides were prepared by the solution polycondensation of the corresponding diacyl chlorides with 4,4′-diaminobibenzyl, trans-4,4′-diaminostilbene, and 4,4′-diaminotolan in N,N-dimethylacetamide (DMAc). Polypyromellitimides were synthesized in two steps by the ring-opening polyaddition of pyromellitic dianhydride with the aromatic diamines in DMAc, followed by thermal cyclodehydration. The amorphous polyisophthalamides were soluble in some amide solvents containing lithium chloride, while the polyterephthalamides having fair degree of crystallinity were insoluble in these solvents. The thermal stability of these aromatic polymers decreased in the order of the tolan-containing polymers > the stilbene-containing polymers > the bibenzyl-containing polymers, both in air and under nitrogen.     

Synthesis and properties of aromatic polyamides containing the cyclohexane structure

1,1-Bis[4-(4-carboxyphenoxy)phenyl]cyclohexane (III) and 1,1-bis[4-(4-aminophenoxy)phenyl]cyclohexane (V) were prepared in two main steps starting from the aromatic nucleophilic substitution of p-fluorobenzonitrile and p-chloronitrobenzene, respectively, with 1,1-bis(4-hydroxyphenyl)cyclohexane in the presence of potassium carbonate in N,N-dimethylformamide (DMF). Using triphenyl phosphite and pyridine as condensing agents, two series of polyamides with cyclohexylidene cardo groups were directly polycondensated from dicarboxylic acid III with various aromatic diamines or from diamine V with various aromatic dicarboxylic acids in an N-methyl-2-pyrrolidone (NMP) solution containing dissolved calcium chloride. The polyamides exhibited inherent viscosities in the range of 0.45 to 1.78 dL/g. Almost all of the polymers were readily soluble in polar aprotic solvents such as NMP and N,N-dimethylacetamide (DMAc) and could afford transparent, flexible, and tough films by solution casting. The glass transition temperatures (T_g) of these aromatic polyamides were in the range of 180–243°C by DSC, and the 10% weight loss temperatures in nitrogen and air were all above 450°C. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 3575–3583, 1999     

Preparation of phosphorus-containing polymers—XVII. Preparation of polyamides containing phenoxaphosphine rings

New phenoxaphosphine-containing polyamides were prepared from 2,8-dichloroformyl-10-phenylphenoxaphosphine 10-oxide (III) and aromatic diamines in DMA by low-temperature solution polycondensation in the presence of triethylamine as acid acceptor. (III) was synthesized by the chlorination of 2,8-dicarboxy-10-phenylphenoxaphosphine 10-oxide derived from 2,8-dimethyl-10-phenylphenoxaphosphine 10-oxide by pyridine-permanganate oxidation. The resulting polyamides had a reduced viscosity of 0.14–0.40 dl/g in DMA or conc. H₂SO₄ at 30°. They were soluble in conc. H₂SO₄ and some of them dissolved in DMA, DMF and DMSO, but all were insoluble in benzene and formic acid, etc. They had good thermal stability, hardly degrading until a temperature of about 400° was reached; they showed resistance to ignition.     

Preparation and properties of polyamides and polyimides derived from 1,3-diaminoadamantane

1,3-Diaminoadamantane (I) was used as a monomer with various aromatic dicarboxylic acyl chlorides and dianhydrides to synthesize polyamides and polyimides, respectively. Polyamides having inherent viscosities of 0.10–0.27 dL/g were prepared by low-temperature solution polycondensation. The polyamides were soluble in a variety of solvents such as N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), N-methyl-2-pyrrolidone (NMP), pyridine, dioxane, and nitrobenzene. These polyamides had glass transition temperatures in the 179–187°C range and 5% weight loss temperatures occurred at up to 354°C. Polyimides based on diamine I and various aromatic dianhydrides were synthesized by the two-stage procedure that included ring-opening to form polyamic acids, followed by thermal conversion to polyimides. The polyamic acids had inherent viscosities of 0.14–0.38 dL/g. The glass transition temperature of these polyimides were in the 245–303°C range and showed almost no weight loss up to 350°C under air and nitrogen atmosphere. © 1996 John Wiley & Sons, Inc.     

Thermal properties of polyamides containing 1,3–cyclohexane rings

The effect of the 1,3–cyclohexane rings in the chain backbone on thermal properties of polyamides, especially the glass-transition temperature, has been studied using polyamides based on 1,3–cyclohexanebis(methylamine). The increase in glass-transition temperature was far greater than that obtained with the analogous polymers containing m–benzene rings. However, the effects of 1,4–cyclohexane and p-benzene rings are nearly equal. Several possible causes for this difference are examined. It is concluded that restricted chain mobility due to steric hindrance of the cis-1,3–cyclohexane ring, the predominant isomer, is the most likely cause of the difference.     

Synthesis and catalytic properties of tetraorganodistannoxanes containing silicon

Three tetraorganodistannoxanes containing silicon were synthesized and their catalytic properties in esterification and acetalization were observed via the reactions of acetic acid with isoamyl alcohol and butyraldehyde with glycol. The factors affecting the reaction, such as the catalyst dosage, reaction time and solvent, etc. were discussed. The results show that the three tetraorganodistannoxanes displayed similar good catalytic activities compared to dichlorotetrabutyldistannoxane in esterification and acetalization. When the dosage of [ClBu₂SnOSn-(CH₂SiMe₃)₂Cl]₂ was 1.5% based on the mass of reactant, the yield of isoamyl acetate was 91.8% and the yield of butyraldehyde glycol acetal 94.2%. The different alkyl and bridging groups on Sn sites in the structure of tetraorganodistannoxanes showed some influence on the catalytic activities of these compounds. __________ Translated from Chinese Journal of Applied Chemistry, 2007, 24 (11): 1265–1272     

Crystallinity and thermal properties of polyamides containing cis- and trans-1,3-cyclohexane rings

The cyclohexane ring-containing polyamide 1,3-CBMA-6 was synthesized from 1,3-cyclohexane-bismethylamine (1,3-CBMA) and adipic acid (6), and effects of cis/trans isomers of the ring on crystallinity and thermal properties were studied. Polymers with high cis and high trans contents, respectively, were made by polymerizing the 1,3-CBMA-6 salts of 98% cis and 93% trans derived from the salt of 75/25 (cis/trans) by fractional crystallization. A polymer with 97% cis content was highly crystalline, with a melting temperature of 253°C, while one with 93% trans contents was amorphous. In contrast to this, little difference was found in the glass transition temperature of 97 and 84°C. These results indicate that the isomers affect the conformation of the molecular chains, which determines the crystallinity and melting temperature, but they do not much affect the mobility of the chains as manifested by the glass transition.     

Thermal properties and solubility of ordered aromatic polyamides containing a methyl-substituted phenylene linkage

Ordered aromatic polyamides and copolyamides were prepared by the polycondensation of terephthaloyl and isophthaloyl dichlorides with symmetrical diamines containing preformed amide linkages derived from unsymmetrical methyl—substituted aromatic diamines at low temperature. Thermal properties and solubilities of the ordered polyamides were compared with those of the corresponding random polyamides. There was little difference between thermal stabilities of the ordered polyamide and the corresponding random one, while the former was less soluble in organic solvents than the latter, depending on the extent of hydrogen bonding of the amide groups. The thermal stability of the alternating copolyamides containing both terephthaloyl and isophthaloyl groups as acid components was less than that of the corresponding homopolymers having either a terephthaloyl or an isophthaloyl group, and the solubility of the former resembled that of the corresponding ordered homopolysiophthalamides in accord with the extent of hydrogen bonding of the amide groups in both polymers.     

Synthesis and liquid-crystalline properties of thermotropic polyamides containing flexible rodlike units and aliphatic spacers

New polyamides with high molecular weights consisting of flexible rod-like mesogenic units (4,4'-diphenyl and 3,4'-diphenyl moieties having bent linkages in the central parts) and aliphatic spacers were synthesized and the thermotropic liquid-crystalline properties were investigated. Differential scanning calorimetry, texture observations by polarizing microscopy, miscibility tests and X-ray analysis suggested that the polymers showed well-defined thermotropic smectic mesophases. The polyamides containing 4,4'-diphenyl moieties had higher transition temperatures and formed more stable liquid-crystalline phases than the polyamide composed of the 3,4'-diphenyl unit with a kinked bond.     

Aromatic polyamides containing keto-benzocyclobutene pendants

A series of novel benzocyclobutene (BCB)-pendanted polyamides (inherent viscosities: 0.20–0.69 dL/g) was synthesized from 3,5-diaminophenyl-4-benzocyclobutenyl ketone, and terephthaloyl, isophthaloyl, 4,4′-oxydibenzoyl chlorides, as well as 4,4′-(o-phenylenedioxy)dibenzoyl chloride. The DSC studies demonstrated that the BCB crosslinking exothermic transition occurred at nearly the same temperature (max. ∼︁ 275°C) for all the four polyamides, and they were thermally stable up to 380°C in helium, where the weight loss started to occur. TGA and DSC studies in air indicated that the polymers, in contrast to the model compound, showed evidence of oxidation just prior to or occurring simultaneously with the BCB crosslinking reaction. This could be attributed to the oxidation of the reactive diene generated from the ring-opening of the BCB competing with the process of two BCB pendant units approaching each other for crosslinking reaction. Preliminary examination of the BCB-pendanted polyamide regenerated from a methanesulfonic acid solution indicates that the BCB ring is quite stable (DSC evidence) in the strong acid medium. © 1996 John Wiley & Sons, Inc.     

Heterocyclic polyamides containing hexafluoroisopropylidene groups

New heterocyclic polyamides have been synthesized by solution polycondensation of aromatic diamines containing phenylquinoxaline units with diacid chlorides having both imide and hexafluoroisopropylidene (6F) groups. These polymers are soluble in polar aprotic solvents, such as N-methylpyrrolidone (NMP) or N, N-dimethylformamide (DMF), and can be cast into flexible thin films from solutions. They show high thermooxidative stability with decomposition temperatures above 400°C and glass transition temperatures in the range of 225-300°C. The polymer films exhibit good chemical resistance towards diluted acids and good electrical insulating properties with dielectric constants in the range of 3.2–3.7.     

Synthesis,characterization and properties of novel polyamides containing ferrocene unit and flexible spacers

Synthesis and characterization of ferrocene‐containing main‐chain polyamides are reported in this article. A new, interesting type of organometallic monomer (FDADO) based on ferrocene was prepared by interfacial condensation of 1,1′‐dichlorocarbonyl ferrocene with 2 mol 1,8‐diamino‐3,6‐dioxaoctane (DADO). A series of ferrocene‐based polyamides was prepared via polycondensation of the ferrocenyl diamine (FDADO) with different diacid chlorides using two different methods. The monomer and polymers were characterized by elemental analysis, infrared and NMR spectroscopy. The thermal stability and behavior of the synthesized polymers were evaluated by thermal gravimetric analysis (TGA), dynamic mechanical thermal analysis (DMTA), and differential scanning calorimetry (DSC). The crystallinity of polymers was examined by X‐ray diffraction analysis. Inherent viscosity, solubility and flame‐retardancy of the polymers were also studied. The obtained polymers showed good heat‐resistance and flame‐retardancy, and improved solubility vs generally reported polyamides in some common organic solvents. Copyright © 2007 John Wiley & Sons, Ltd.