Soluble aromatic polyamides modified by incorporation of 1,2,4-triazole and pentadecyl units into the backbone of polymer

Abstract

A new series of soluble aromatic polyamides was synthesized by low temperature solution polycondensation of novel aromatic diamine namely 3,5-bis-(4′-amino phenyl)-4-(4″-methoxy-2″-pentadecyl phenyl) 1,2,4-triazole (VII) with aromatic diacid chlorides, viz. isophthaloyl chloride (IPC) and terephthaloyl chloride (TPC). The aromaticdiamine (VII) was characterized by elemental analysis, FT-IR, NMR (¹H, ¹³C), and mass spectrometry. Copolyamides were also synthesized by employing various mole proportions of IPC and TPC with diamine (VII). Inherent viscosities of these polyamides were in the range of 0.50–0.65 dL/g in DMAc, indicating formation of moderate to high molecular weight of polyamides. These polyamides showed good solubility in polar aprotic solvents such as N,N-Dimethyl acetamide (DMAc), N-Methyl 2-pyrrolidone (NMP), N, N, Dimethyl formamide (DMF), and Dimethyl sulphoxide (DMSO), which may be due to incorporation of pendant methoxyphenyl moiety with pentadecyl units. The amorphous morphology of polyamides as evidenced by XRD. These polyamides had lower glass transition temperatures; as determined by DSC, compared to the T_g of conventional aromatic polyamides due to internal plasticization effect of long alkyl pentadecyl group. Polymers showed good thermal stability, with initial decomposition temperature above 300?°C.     

Intramolecular excimer formation in polyamides with widely separated naphthyl groups in the backbone

The photophysical properties of a series of polyamides containing naphthalene groups in the backbone were investigated. The polyamides were synthesized by interfacial polycondensation involving 2,6-bis(N-methyl, methylamino)naphthalene and the following diacid chlorides: (x = 2, 4, 6, and 8). The polyers were designated P-2, P-4, P-6, and P-8. The monomer model compound (MC) was made by acylation of the diamine monomer wth acetyl chloride. The polyamides exhibited intramoleular excimer fluorescence in dilute solutions at room temperature. Excimer fluorescence quantum yields were in the following order: P-2 ≈ P-8 > P-4 ≈ P-6. This sequence was rationalized on the basis of neighboring and nonneighboring group excimeric interactions that are dependent on the length of the intervening methylee chain. Temperature measurements on P-2 revealed a small energy of actvation (1.8 kcal mole^?1) for the conformational transition involved in the formaton of the intramolecular excimer. Intramolecular excimer formation for a given polymer depended on the solvent. Nanosecond fluorescence depolarization measurements demonstrated the flexibility of the naphthalene moieties even though they were doubly bound in the polymer chain. Our results showed that intramolecular excimer formation could occur over long distances of separation (n > 3) between the nteracting chromophores provided that the connecting chain was sufficiently flexible.     

Linear A–B and AA–BB polyamides with backbone aryl,alkyl, and alkenyl units

High performance linear AA–BB and A–B polyamides were generated using polymerization schemes that gave polymers in higher yields and having better performance than previous methods. Polymers were characterized with FTIR, solution and solid-state ¹³C-NMR and showed the incorporation of aryl, alkyl, and alkenyl linkages in the polymer backbone. Thermal analysis showed that a significant weight percent of the polymers remained at 1000°C.     

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.     

Rigid rod polymers with regularly spaced silicon-centered phthalocyanine units in the backbone

We describe the synthesis of new rigid rod polymers possessing a backbone of silicon phthalo-cyanine units and stiff 4,4′-dioxybiphenyl or 2,6-dioxynaphthalene spacers. These modified phthalocyaninato-polysiloxane derivatives are characterised by mass, absorption and ¹³C-CPMAS spectroscopies, differential scanning calorimetry and X-ray powder diffractometry. UV/VIS spectra show only slight differences to the corresponding phthalocyanine monomers, which indicates the absence of excited state interactions between the chromophores within the polymer backbone.     

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.     

Heat-resistant polymers with thianthrene analog units. II . Aromatic polyamides

A series of polyamides which contained thianthrene, phenoxatiin, and dibenzo-p-dioxin units was synthesized from tricyclic fused-ring diamines and aromatic diacid chlorides by solution polycondensations at a low temperature. The amorphous polyisophthalamides were highly soluble in polar organic solvents, whereas some of the polyterephthalamides with a fair degree of crystallinity were insoluble. The solubility of the series of polyamides increased in the order of the dibenzo-p-dioxin-containing polymers < phenoxatiin-containing polymers < thianthrene-containing polymers. The thermal stability increased in the reverse order and the dibenzo-p-dioxinpolyamides were more thermostable than the corresponding open-chain polymers with diphenyl ether linkages. The polyamides derived from 2,8-oriented tricyclic diamines showed somewhat lower glass transition temperatures than those from 2,7-oriented diamines.     

New photo- and electroluminescent conjugated copolyfluorenes with 7,8,10-triarylfluoranthene units in the backbone

A new monomer, the dibromo derivative of fluoranthene 1-[7,10-bis(4-bromophenyl)fluoranthen-8-yl]pyrene, is synthesized and used to prepare three new copolyfluorenes containing 3, 5, and 10 mol % 7,8,10-triarylfluoranthene groups via the Yamamoto reaction. The number-average molecular masses and polydispersities of the polymers vary in ranges 41900?C78900 and 2.7?C3.5, respectively. All polymers are soluble in common organic solvents, and their glass-transition temperatures are from 95 to 115°C. Temperatures corresponding to a 10% loss in weight during heating in argon and air are in the ranges 420?C435 and 405?C415°C, respectively. The photoluminescence spectra of the polymers exhibit strong blue emission with a maximum at 418 nm, whereas the absorption spectra show characteristic peaks at 351?C357 nm. All polymers possess reversible or partially reversible redox behavior owing to high electric activity and demonstrate redox pairs at 1.51 eV (oxidation) and ?2.09 eV (reduction).     

Synthesis and photophysical properties of polyphenylquinoxalines with thiophene and dibenzothiophene units in the backbone

New bis(α-diketones) containing thiophene and dibenzothiophene groups were synthesized. Via the reaction of these monomers with aromatic tetramines under high-temperature polycondensation conditions, a series of new polyphenylquinoxalines combining high thermal and mechanical characteristics with solubility in organic solvents were prepared. Polyphenylquinoxalines exhibit intense fluorescence in solution and in thin films with maxima in the region of 432–522 and 450–530 nm in the case of thiophene-containing and dibenzothiophene derivatives, respectively.     

Synthesis and characterization of polyamides containing heterocyclic thiaxanthone units

Novel polyamides containing heterocyclic thiaxanthone units were prepared by condensing 2,7-dichloroformylthiaxanthone-5,5′-dioxide and 2,8-dichloroformylthiaxanthone-5,5′-dioxide with various aromatic diamines, under low temperature solution polymerization conditions in DMAc. The model diamide, 2,8-ditolylcarbamylthiaxanthone-5,5′-dioxide was synthesised and characterized by spectroscopic methods. The polyamides were prepared in 70–80% yield and had inherent viscosity in the 0.36–0.73 dL/g range. The poyamides have decomposition temperatures in the 425–510°C range in nitrogen. The effect of thiaxanthone rings on polymer backbone on solubility, crystallinity, and thermal stability is also discussed.     

Novel polyamides with acyclic and cyclic bipyridinediyl diamino structures in the polymer backbone: Synthesis and complexation with transition metals

The synthesis of two novel polyamide ligands 3 and 4 , containing 2,17-diaza[3.3](6,6′)-2,2′-bipyridinophane or 6,6′-bis(2-picolylaminomethyl)-2,2′-bipyridine units as part of the polymer backbone, respectively, and of the appropriate diamide model compounds 1c and 2c is described. ¹H-NMR and IR spectral data support the ligand structures; furthermore, ¹H-VTNMR analysis on macrocyclic diamide 1c indicates a restricted rotation of the amide bonds at ambient temperature and suggests for this molecule a fixed syn conformation in solution, with a “face to face” arrangement of the dipyridinyl moieties. Model compound 2c and polyamide 4 form stable 1:1 complexes with transition metals Co(II), Ni(II), and Cu(II). Conversely, macrocyclic model 1c and polyamide 3 exhibit the unique property to specifically complex Cu(II), even in the presence of sizeable amounts of Co(II) and Ni(II). The IR spectral changes related to the ligands upon complexation are briefly discussed.     

Heat-resistant, pyridine-based polyamides containing ether and ester units with improved solubility

<正>A diamine containing ether and ester units,as basic monomer for the preparation of polyamides,was prepared via three consecutive reactions.Nucleophilic substitution reaction of 1,4-dihydroxy benzene with 4-nitrobenzoyl chloride produced 4-hydroxyphenyl 4-nitrobenzoate(HPNB).Reduction of nitro groups to amino groups using Fe and HC1 resulted in preparation of 4-hydroxyphenyl 4-aminobenzoate(HPAB).The diamine was synthesized through nucleophilic substitution reaction of HPAB with 2,6-dichloropyridine The precursors and diamine were fully characterized by common methods,and the diamine was polycondensed with different diacid chlorides in the presence of an acid scavenger to prepare new polyamides.The polyamides were characterized,and their physical properties including thermal stability and behavior, inherent viscosity and solubility were studied.     

Melt-processable oligoamides having internal acetylene groups in the backbone,and thermally stable polyamides therefrom

Aromatic oligoamides of DP = 5 and 11 that have all meta-phenylene linkages were prepared by controlling the ratio of isophthaloyl chloride and diamines [m-phenylenediamine and bis(3-aminophenyl)acetylene], and then end-capped with aniline or 2-aminobiphenylene. Aromatic oligoamides having para-phenylene linkages were also prepared similarly using terephthaloyl chloride as a monomer. The oligoamides that have all m-phenylene linkages were soluble in organic solvents such as N-methyl-2-pyrrolidone and N,N-dimethylacetamide, though the oligoamides having p-phenylene linkages were much less soluble. The oligoamides having acetylene units in the backbone showed exotherm due to crosslinking. The onset of the exotherm appeared at 310-340°C for the oligoamides having all m-phenylene linkages, and 330-370°C for the oligoamides having p-phenylene linkages. They were melt-processed at 350 or 380°C for 1 h, giving tough and insoluble films from oligoamides having all m-phenylene linkages and brittle films from oligoamides having p-phenylene linkages. The films showed excellent thermal properties. For example, viscoelastic analyses showed little decrease of mechanical property up to 370°C, and T_g was not observed below the temperature. Thermogravimetric analyses also showed that thermal stability of the melt-processed films were excellent. © 1992 John Wiley & Sons, Inc.     

N-Alkyl-substituted polyamides and copolyamides having long methylene chain units

N-Alkyl-substituted polyamides and copolyamides have been prepared from N,N′-dialkyl p-xylenediamine and N,N′-dialkyl hexamethylenediamine with long-chain aliphatic dicarboxylic acids. Crystalline N-alkyl polyamides were obtained by the use of dicarboxylic acids higher than C₁₆. The melting point versus composition curves for the crystalline N-alkyl copolyamides which were prepared from a mixture of diamine and the corresponding N-alkyl diamine with α,ω-octadecanedioic acid showed convex type plots. X-ray examination of N-alkyl copolyamides revealed that all the systems behaved in the same basic manner, the second component was always present without dissolving in the lattice of the first. Dilatometric curves showed two inflection points, corresponding to the melting points of the N-alkyl and unsubstituted polyamides respectively. From these results, a block copolymer structure was suggested for the N-alkyl copolyamides. The mechanisms for the formation of the block structure were also discussed.     

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.