Synthesis,thermal and optical properties of nanosized polyamides containing N-phenyl- and N-naphthyl-s-triazine rings: Structure-properties correlation

We prepared two series of nanosized polymers containing s-triazine moiety by reactions of newly prepared substituted diacids chlorides derived from 2-anilino-4,6-di-(phenoxy)- and 2-(N-1-naphthylamine)-4,6-di-(phenoxy)-s-triazines with a number of commercial diamines. The polymers were carefully characterized by different techniques including infrared, ultraviolet, fluorescent emission, elemental and thermal analyses and scanning electron microscopy (SEM). The SEM images indicated that most of the polyamides were organized as well defined nano sized spheres, but in certain derivatives small amount of aggregated nanospheres was also observed. Structure-property correlations based on a single or more interchange proved to be feasible. The polymers exhibited high thermal behavior and, based on the produced char yields, the limiting oxygen index (LOI) indicated that a dozen polymers were classified as “slow burning polymers” while the other dozen polymers were “self-extinguishing polymers.” Polymers derived from symmetric diamine exhibited better thermal stability than those containing asymmetric diamines. Interestingly, while the naphthyl/phenyl interchange has no influence on the thermal properties in some cases, however, dramatic improvements were noticed in many other cases. Obviously, the pyridine/phenylene interchange has no influence on the thermal properties of the addressed polymers. The polymers exhibited emissions ranging from blue to orange wavelength depending on the nature of the signaling unit. While the introduction of a naphthyl moiety has no significant influence on the electronic properties in some cases, however, the interchange led to either appreciable red-shifted absorptions or disrupt the conjugation and thus blue-shifted absorptions in other analogues. This result enables such polymers as good candidates in different technological applications.     

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.     

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.     

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,characterization and corrosion inhibitive properties of new thiazole based polyamides containing diarylidenecyclohexanone moiety

The present work aimed to synthesize a new interesting series of thiazole based polyamides containing diarylidenecyclohexanone moiety 5a-5f using low temperature solution polycondensation technique. The new polymers were synthesized by the reaction of thiazole based monomer namely, bis(2-aminothiazol-4-ylbenzylidene)cyclohexanone 3 with different aliphatic and aromatic diacid chlorides using NMP, and in the presence of anhydrous Li Cl as catalyst. Adipoyl, sebacoyl, oxaloyl, terephthaloyl, isophthaloyl dichlorides and biphenyl dicarbonyl dichloride were used as diacid chlorides. The structure of the model compound 4 as well as the new polymers was confirmed by correct elemental and spectral analyses. The thermal properties of those polymers were evaluated by TGA and DTG measurements and correlated to their structural units, beside X-ray diffraction analysis, solubility and viscometry measurements. The inherent viscosities for the synthesized polymers were in the range 0.6–1.03 d L/g. On the other hand the corrosion inhibitive properties of monomer 3 as well as polyamides 5d and 5f as selected examples were carried out on carbon-steel in 0.5 mol/L H2SO4 at 40 °C. The calculated inhibition efficiency(IE%) for polymer 5d was in the range(82 ± 6)% in all selected concentrations. The best value of IE% was obtained at 1 mg/L to reach 98.24% for polymer 5d and at 0.5 mg/L to reach 87.75% for polymer 5f.     

Synthesis and thermal properties of a new class of high-temperature polyamides from hexahydrobenzodipyrrole

A series of polyamides was synthesized by the interfacial polycondensation of 1,2,3,5,6,7-hexahydrobenzo [1,2-c:4,5-c′] dipyrrole with isophthalic, terephthalic, oxydibenzoic, sebacic and adipic acid chlorides. High molecular weight polymers with inherent viscosities ranging from 0.4 to 2.3 dl/g were obtained. Polymerization with isophthaloyl chloride gave the highest molecular weight polymer in this series. These polyamides melt between 350°C and 475°C, depending on structural differences as determined by differential scanning calorimetry (DSC). Rapid weight loss in these polymers was observed in the range of 350–400°C under thermogravimetric analysis in a nitrogen atmosphere. All these polyamides are susceptible to photooxidative degradation. The results were compared with Nomex polymer poly(1,3-phenylene isophthalamide).     

Synthesis,characterization, and water sorption properties of new aromatic polyamides containing benzimidazole and ethylene oxide moieties

New polyamides, containing a benzimidazole side group and ethylene oxide moieties in the structural repeat unit, were synthesized by low‐temperature polycondensation. The aim of this design was to obtain polyamides that were more soluble in common organic solvents and hence had better processability than benzimidazole polyamides while maintaining the water sorption properties characteristic of the latter. The results showed that the number of ether linkages of the repeat unit played an important role in the glass‐transition temperature and in the water sorption properties, the polyamides with one or two ethylene oxide units being more hydrophilic than benzimidazole polyamides. However, the length of the ethylene oxide chain played a minor role in the solubility because the second member of the series, with two ether linkages (i.e., one ethylene oxide unit), reached the same level of solubility as those polyamides with more ethylene oxide moieties. No crystallinity was observed by X‐ray and calorimetric measurements for the new polymers. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 112–121, 2005     

Synthesis and characterization of aromatic polyamides containing S-triazine rings in the main chain

Ten new aromatic polyamides containing s-triazine rings in the main chain were synthesized by the low temperature interfacial polycondensation technique involving the reactions of each of the two s-triazine containing diacylchlorides, viz., 2,4-bis (4-chlorocarbonylphenoxy)-6-methoxy-s-triazine and 2,4-bis(3-chlorocarbonylphenoxy)-6-methoxy-s-triazine, with five aromatic diamines namely, 4,4′-bis(4-aminophenoxy)diphenyl sulfone, 4,4′-bis(3-aminophenoxy)diphenyl sulfone, 2,2-bis[4(4-aminophenoxy) phenyl] propane, 1,4 bis (4-amino-phenoxy) benzene, and 1,3-bis (4-aminophenoxy)benzene. The resulting polyamides were characterized by viscosity measurements, IR and ¹H-NMR spectroscopy, solubility tests, x-ray diffraction, and thermogravimetry. The polyamides had inherent viscosities in the range of 0.16–1.06 dL/g in N,N-dimethylacetamide at 30°C. Most of the s-triazine containing polyamides dissolved readily at room temperature in polar solvents. Except for the polyamide PA-2, the polyamides did not lose weight below 350°C under a nitrogen atmosphere. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 1077–1085, 1997     

Synthesis and mesomorphic properties of some new chiral thiobenzoates containing three rings

Six new compounds with chiral terminal chains and three rings bridged via the -COS- and -COO- groups have been synthesized. Three of them belong to series A and have two benzene rings and one bicyclo[2,2,2]octane, while the remaining three come from series B, where all three are benzene rings. Series A compounds share a characteristic feature of two smectic phases: SmA* and SmB*, whereas mesogens from the B series exhibit only the one SmA* phase.     

Synthesis,characterization, and properties of semifluorinated organo‐soluble new aromatic polyamides

A series of organo‐soluble new polyamides were synthesized by the direct polycondensation of different semifluorinated aromatic diamines, namely 4,4‐bis[3'‐trifluoromethyl‐4'(4“‐amino benzoxy)benzyl]biphenyl; 4,4”‐bis(aminophenoxy)‐3'3“‐trifluoromethyl terphenyl; 1,3‐bis[3'‐trifluoromethyl‐4'(4”‐amino benzoxy)benzyl]benzene; 2,6‐bis(3'‐trifluoromethyl‐p‐aminobiphenyl ether)pyridine; and 2,5‐bis(3'‐trifluoromethyl‐p‐aminobiphenyl ether)thiophene with 5‐t‐butyl‐isophthalic acid. The polymers were fully characterized by elemental analysis and IR, NMR spectroscopies. The synthesized polyamides were soluble in several organic solvents such as 1‐methyl‐2‐pyrrolidone, N,N‐dimethylformamide, N,N‐dimethylacetamide, tetrahydrofuran, and dimethyl sulfoxide at room temperature. They showed inherent viscosities of 0.42–0.63 dl/g. The polyamides exhibited weight‐average molecular weights of up to 233,000, which depended on the exact repeating unit structure. The polyamides synthesized from 4,4‐bis[3'‐trifluoromethyl‐4'(4”‐amino benzoxy)benzyl]biphenyl and 5‐t‐butyl isophthalic acid exhibited highest glass‐transition temperatures 261°C (evaluated by differential scanning calorimetry) in nitrogen. These polyamides showed good thermal stability up to 475°C for a 10% weight loss in air. The polyamides films were clear and flexible in nature with tensile strengths of up to 88 MPa, modulus of elasticity of up to 1.81 GPa, and elongations at break of up to 25%, which depended on the exact repeating unit structure. X‐ray diffraction measurements indicated that these polyamides were amorphous in nature. Copyright © 2010 John Wiley & Sons, Ltd.     

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     

Synthesis and properties of disulfide-bond containing eight-membered rings

The cyclocystine ring structure (CRS, 3), which results from a disulfide-bond between adjacent cysteine residues, is a rare motif in protein structures and is functionally important to those few proteins that posses it. This letter will focus on the construction of CRS mimics and the determination of their respective redox potentials.     

Synthesis and characterization of organo‐soluble polyamides containing triaryl imidazole pendant and ether linkage moieties: thermal,photophysical, and chemiluminescent properties

A new symmetrical diamine monomer containing a triaryl imidazole pendant group was successfully synthesized by the nucleophilic substitution of hydroquinone with the synthesized 2‐(2‐chloro‐5‐nitrophenyl)‐4, 5‐diphenyl‐1H‐imidazole (I). A series of novel polyamides were prepared from the diamine monomer and various aliphatic and aromatic dicarboxylic acids via phosphorylation polyamidation. These polyamides are readily soluble in many organic solvents; their inherent viscosities ranged from 0.68 to 0.89 dl/g and gave tough and flexible films by solution‐casting. They had useful levels of thermal stability associated with relatively high T_gs (186–278°C), 10% weight loss temperatures in the range of 355–482°C, and char yields at 600°C in air up to 67%. All the polyamides have fluorescence emission in dilute (0.2 g/dl) DMAc solution with maxima at 425–495 nm and with the quantum yields in the range 14–28%. The chemiluminescence activity of polyamides was also studied in the presence of peroxyoxalate. Copyright © 2010 John Wiley & Sons, Ltd.     

Polymers containing hydrogen bonding rings. Synthesis and thermal properties of poly(enamine-ketones)

The synthetic route to poly(enamine-ketones) by vinylogous nucleophilic substitution of aromatic bis(1,3-diketones) with aromatic and aliphatic diamines is described. The preparation of aromatic bis(1,3-diketones), their polymerization, and thermal properties of the polymers are presented in detail. The polymers exhibited anisotropic melts and representative model compounds were shown to be thermotropic liquid crystals.     

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.     

Synthesis and characterization of new soluble polyamides containing phthalimide pendent group

A dicarboxylic acid monomer, 5-phthalimidoisophthalic acid, containing a phthalimide pendent group was prepared by the condensation of 5-aminoisophthalic acid and phthalic anhydride in glacial acetic anhydride. The monomer was reacted with various aromatic diamines to produce polyamides using triphenyl phosphite and pyridine as condensing agents. These polyamides were produced with inherent viscosities of 0.64–1.14 dL · g⁻¹. All the polymers, characterized by wide-angle X-ray diffraction, revealed an amorphous nature resulting from the presence of the bulky pendent group. These polyamides exhibited excellent solubility in a variety of solvents such as N- methyl-2-pyrrolidinone, N,N-dimethylacetamide (DMAc), N,N-dimethylformamide, dimethyl sulfoxide, pyridine, and cyclohexanone. These polyamides showed glass-transition temperatures (T_g's) between 247 and 273 °C (by DSC) and 248 and 337 °C (by a dynamic mechanical analyzer). The thermogravimetric analytic measurement revealed the decomposition temperature at 10% weight-loss temperatures (Td₁₀) ranging from 442 to 530 °C in nitrogen. The polyamides containing phthalimide groups exhibited higher T_g and Td₁₀ values than those having no phthalimide groups. Transparent, tough, and flexible films of these polyamides could be cast from the DMAc solutions. These casting films had tensile strengths ranging from 81 to 126 MPa, elongations at break ranging from 7 to 13%, and tensile moduli ranging from 2.0 to 2.9 GPa. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1557–1563, 2001     

Synthesis,characterization, and thermal properties of novel arylene sulfone ether polyimides and polyamides

A new aromatic sulfone ether diamine was synthesized by nucleophilic aromatic substitution reaction of 5‐amino‐1‐naphthol with bis(4‐chlorophenyl) sulfone in the presence of potassium carbonate in a polar aprotic solvent. Polycondensation reactions of the obtained diamine with pyromellitic dianhydride (PMDA), benzophenonetetracarboxylic dianhydride (BTDA), and hexafluoroisopropylidene diphthalic anhydride (6FDA) resulted in preparation of thermally stable poly(sulfone ether imide)s. Poly(sulfone ether amide)s also were prepared by reaction of the diamine with terephthaloyl chloride (TPC) and isophthaloyl chloride (IPC). The prepared monomer and polymers were characterized by conventional methods. Physical and mechanical properties of polymers, including thermal stability, thermal behavior, solution viscosity, solubility behavior, and modulus, also were studied. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 1487–1492, 2000     

Synthesis and properties of oligomers containing substituted bithiazole rings

A series of novel polyimide and poly(Schiff base) oligomers containing substituted bithiazole rings were designed and synthesized, for the first time, by polycondensation of 5,5^′-dimethyl-2,2^′- diamino-4,4^′-bithiazole (MDABT) with dianhydrides (pyromellitic dianhydride, 3,3^′-4,4^′-benzophenone tetracarboxylic dianhydride and bis (3,4-dicarboxyphenyl) ether dianhydride), and dialdehydes (oxalic aldehyde, isophthalaldehyde and terephthalaldehyde). The structure of the oligomers was determined by IR and ¹H NMR spectroscopy, and elemental analysis. The oligomers showed good thermal stability. The Fe²⁺ complex of poly(Schiff base), synthesized from MDABT with oxalic aldehyde (PMTOA), was prepared with 13.7% Fe content and found to be a ferromagnet at low temperature.     

Synthesis and second-order nonlinear optical properties of new chromophores containing benzimidazole, thiophene, and pyrrole heterocycles

A new series of thermally stable benzimidazole-based nonlinear optical (NLO) chromophores 4 and 5 have been developed. These chromophores possess a thienylpyrrolyl π-conjugated system attached to functionalized benzimidazole heterocycles. This feature leads to robust chromophores with excellent solvatochromic properties, high thermal stabilities and good molecular optical nonlinearities.