Synthesis and characterization of some Schiff-base-containing polyimides

The diamine, 4-aminophenyloxy-N-4-[(4-amiophenyloxy)benzylidene]aniline, was prepared via the nucleophilic substitution reaction and was polymerized with different dianhydrides either by one-step solution polymerization reaction or two-step procedure. The latter includes ring-opening polyaddition to give poly(amic acid), followed by cyclodehydration to polyimides. The inherent viscosity ranges from 0.61–0.79 dl/g. Some of the polymers were soluble in most of the organic solvents such as DMSO, DMF, DMAc, NMP, and m-cresol even at room temperature. The degradation temperature of the resultant polymers falls in the ranges from 240–500 °C in nitrogen with only 10% weight loss. Specific heat capacity at 200 °C ranges from 1.0929–2.6275 J g⁻¹ k⁻¹. The temperature at which the maximum degradation of the polymer occurs ranges from 600–630 °C. The glass transition temperature (Tg) values of the polyimides ranged from 185 to 272 °C. The activation energy and enthalpy of the polyimides ranged from 47.5–55.0 kJ/mole and 45.7–53.0 kJ/mole and the moisture absorption in the range of 0.23–0.72%.     

Synthesis and characterization of organosoluble polyamides from quinoxaline based diamine

<正>Aromatic/aliphatic polyamides were synthesized from a diamine monomer,2,3-bis-p-aminophenylquinoxaline (Ⅳ),based on quinoxaline and various dicarboxylic acids of aliphatic,aromatic and heterocyclic.The diamine and polyamides were characterized by elemental analysis,FTIR and ~1H-NMR.The solubility of the polyamides was affected by the quinoxaline and heterocyclic groups in the polymer chain.They were all soluble in common organic solvents such as dimethylsulfoxide(DMSO),N,N-dimethylformamide(DMF) and N-methylpyrolidone(NMP).The polyamides showed inherent viscosity in the range of 0.25-0.3 dL/g in DMSO at 25℃and good thermal stability with the char yields in the range of 65%-82%at 600℃in nitrogen.     

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.     

Synthesis and characterization of polyamides derived from (4-(4-(2, 6-diphenylpyridin-4yl)phenoxy)phenyl)-3, 5-diaminobezamide

New types of polyamides containing pendent triaryl pyridine groups were successfully synthesized by direct polycondensation of a symmetry diamine,（4-（4-（2,6-diphenylpyridin-4yl）phenoxy）phenyl）-3,5-diaminobezamide（DPDAB）, and various aromatic and aliphatic dicarboxylic diacids in NMP using triphenyl phosphate（TPP） and pyridine as catalyst. The diamine and all the prepared polyamides were fully characterized by using FT-IR,¹H-NMR,UV-Vis spectroscopy, fluorimetry and elemental analysis.The inherent viscosity of polyamides ranged from 0.45 dL/g to 0.68 dL/g.All the polymers exhibited solubility in common polar aprotic solvents such as NMP,DMAc,DMF,DMSO,pyridine,HMPA,and even in less polar solvents such as THF and m-cresol at room temperature.Thermal properties of polyamides were evaluated by means of DSC,DMTA and TGA.These polymers showed glass transition temperatures（T_g） in the range of 138-210℃. Their initial decomposition temperature（T_i） varied from 265℃to 310℃under N₂.The dilute solution（0.2 g/dL） of polyamides in DMF exhibited fluorescence emission withλ_max in the range of 470-550 nm.     

Synthesis and characterization of novel aromatic polyamides derived from two heterocyclic diamines

Two diamines were synthesized as new aromatic monomers. A series of novel aromatic polyamides (aramids) were also synthesized by direct and indirect polycondensation of these diamines with various aromatic dicarboxylic acids. These aramids have inherent viscosities of 0.43-0.84 dl/g and were obtained in quantitative yield.     

含异丙基及三氟甲基可溶性聚酰胺的合成及性能研究

以含异丙基和三氟甲基结构二胺单体3,3′-二异丙基-4,4′-二胺基苯基-4″-三氟甲基甲苯(PATFT)与萘-1,4-二甲酸、间苯二甲酸和4,4-二苯醚二甲酸3种二酸通过膦酰化反应制备一系列新型可溶性聚酰胺,其相对分子量在3.8×104~9.6×104之间.结果表明,该聚合物具有优异的溶解性能,常温不仅能溶解于N-甲基吡咯烷酮(NMP)、N,N-二甲基乙酰胺(DMAc)、N,N-二甲基甲酰胺(DMF)等高沸点有机溶剂,在加热条件下甚至能较好的溶解在四氢呋喃、氯仿、二氯甲烷等低沸点溶剂中;突出的光学性能,截止波长范围在322~350 nm,80%的透过率波长范围为378~403 nm;良好的热学性能,玻璃化转变温度(Tg)范围在213~220?C,氮气氛围下5%和10%热失重温度范围分别为453~458?C和470~482?C.聚合物薄膜具有优异的机械性能,拉伸强度、杨氏模量、断裂伸长率分别对应为68~97 MPa,1.9~2.9 GPa,14.8%~16.7%.广角X-射线图谱表明聚合物为无定形态结构.     

Synthesis of organosoluble polyamides with bulky triaryl imidazole pendent group

New unsymmetrical diamine monomer containing triaryl imidazole pendent group,4-[4-(4,5-diphenyl-1H-imidazol-2-yl)phenoxy] -1,3-benzenediamine,was synthesized via aromatic substitution reaction of 1-chloro-2,4-dinitrobenzene with 4-(4,5- diphenyl-1H-imidazol-2-yl)phenol,followed by palladium-catalyzed hydrazine reduction.This new monomer was further confirmed by FT-IR,~1H NMR and ~(13)C NMR.Novel polyamides having pendant triaryl imidazole group were prepared by the phosphorylation polycondensation of fou...     

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.     

Synthesis and characterization of some new Schiff base polymers

Seven Schiff base polymers poly 5,5^′-methylenebis(2-hydroxyacetophenone)semicarbazone (PHASC), poly-5,5^′-methylenebis(2-hydroxyacetophenone)thiosemicarbazone (PHATS), poly 6,6^′-methylenebis(2-hydroxynaphthaldehyde)1,2-propylenediimine (PHNPn), poly 6,6^′-methylenebis (2-hydroxynaphthaldehyde)1,3-propylenediimine (PHNPR), poly 6,6^′-methylenebis (2-hydroxy-naphthaldehyde)thiosemicarbazone (PHNTS), poly 6,6^′-methylenebis(2-hydroxy-naphthaldehyde)urea (PHNU) and poly-6,6^′-methylenebis(2-hydroxynaphthaldehyde)semicarbazone (PHNSC) were prepared by polycondensation of 5,5^′-methylenebis(2-hydroxyacetophenone) (MHA) or 6,6^′-methylenebis(2-hydroxynaphthaldehyde) (MHN) with semicarbazide, thiosemicarbazide, 1,2-propylenediamine, 1,3-propylenediamine or urea. The polymers were characterized by elemental micro-analysis, infrared and ultraviolet spectroscopy and viscosity measurements. The reduced viscosity of the polymers measured in dimethylformamide (DMF) was observed in the range 0.32-0.63 dl/g.     

Synthesis and characterization of new polyphenols derived from o-dianisidine: The effect of substituent on solubility, thermal stability, and electrical conductivity, optical and electrochemical properties

In this study, we proposed to synthesize soluble polyphenol derivatives containing azomethine bond. For this reason, o-dianisidine was chosen to synthesize Schiff base monomers due to containing dimethoxy groups. Four phenolic Schiff bases were synthesized by condensation reaction of o-dianisidine with salicylaldehyde (2-HBADIAN), 4-hydroxybenzaldehyde (4-HBADIAN), vanillin (MHBADIAN) and 3-ethoxy-4-hydroxybenzaldehyde (EHBADIAN). These monomers were converted to their polyphenol derivatives via oxidative polycondensation reaction (OP). The structures of the obtained compounds were confirmed by FT-IR, UV-vis, ¹H NMR and ¹³C NMR techniques. Progressing of OP was also followed by a time-controlled spectrum mode of a UV-vis spectrophotometer. The molecular weight distribution parameters of the synthesized polyphenols were determined by the size exclusion chromatography (SEC). The synthesized compounds were also characterized by solubility tests, TG-DTA and DSC. Cyclic voltammetry (CV) measurements were carried out and HOMO-LUMO energy levels and electrochemical band gaps () were calculated. Additionally, optical band gaps (E_g) were determined by using UV-vis spectra of the materials. Electrical conductivities of both doped and undoped states of the synthesized materials were measured by four-point probe technique using a Keithley 2400 electrometer showing that P-2-HBADIAN has approximately 130 times higher electrical conductivity than the others. Also, it was stressed that the synthesized polyphenols are semiconductors which have a potential for electronic and optoelectronic applications, with fairly low band gaps.     

Synthesis and characterization of new cardo poly(bisbenzothiazole-urea)s containing bulky pendant groups

A series of novel rigid poly(bisbenzothiazole-urea)s (PBTUs III) containing bulky pendant groups were synthesized from 2,2-diaminodibenzothiazoles and aromatic diisocyanates conveniently in the mild condition. The inherent viscosity, solubility, thermal stability, morphology, mechanical and photophysical properties of them were investigated and compared in detail. The inherent viscosities were in the range of 0.58-0.73 dL/g. All of the polymers exhibited excellent solubility in various polar organic solvents. They also showed good thermal stability and mechanical properties. The decomposition temperatures at 10% weight loss were in the range of 368-431 °C in nitrogen. All the PBTUs III were amorphous. Tensile strength of PBTUs III showed the range from 85 to 98 MPa. Compared with poly(benzothiazole)s, all the PBTUs III had the larger optical bandgap and lower photoluminescence quantum yields.     

Synthesis and characterization of dicationic ionic liquids that contain both hydrophilic and hydrophobic anions

A series of dicationic ionic liquids, in which each dication is associated with both a hydrophobic anion and a hydrophilic anion, are synthesized. The thermal properties and solubility in organic solvents of these ILs are characterized. The ionic liquids show interesting properties, which are different from those of dicationic ionic liquids, in which each dication is associated with two identical anions.     

Syntheses and characterization of poly(iminophenol)s derived from 4-bromobenzaldehyde: Thermal, optical, electrochemical and fluorescent properties

Schiff base monomers[2-（4-bromobenzylideneamino）phenol and 2-（4-bromobenzylideneamino）-5-methylphenol] were synthesized by the condensation reaction of 4-bromobenzaldehyde with aromatic aminophenols.Then,the monomers were converted to their polyphenol derivatives by oxidative polycondensation reactions（OP） in an aqueous alkaline medium. The structures of the synthesized compounds were characterized by solubility tests,FT-IR,NMR,TG-DTA,DSC and SEC techniques.The HOMO-LUMO energy levels and electrochemical（E_g ） and optical（E_g） band gaps were calculated from cyclic voltammetry（CV） and UV-Vis measurements,respectively.Cyclic voltammetry（CV） was used to determine the electrochemical oxidation-reduction characteristics.Optical properties were investigated by UV-Vis and fluorescence analyses.Solid state electrical conductivities were measured on polymer films by four point probe technique using a Keifhley 2400 electrometer.The effects of electron-donating（-CH₃） group at p-position of -NH₂ group in aminophenol on electrochemical and thermal properties were also discussed.Photoluminescence（PL） properties of the synthesized materials were determined in solution forms using different solvents.Fluorescence measurements were carried out in various concentrated solutions to determine the optimum concentrations to obtain the maximal PL intensities.     

Synthesis and characterization of processable polyamides containing polar quinoxaline unit in the main chain and evaluation of its hydrophilicity

Here we report a new five polyamides prepared via solution-phase polycondensation under Yamazaki-Higashi conditions to prove the suitability of this method. The synthesized polyamides were characterized by FTIR, ¹H-NMR, differential scanning calorimetry, thermogravimetric analysis, inherent viscosity, solubility and wettability tests. These polyamides were amorphous in nature and they are completely soluble in many organic solvents and they could easily be solution-cast into transparent, flexible films. The as-prepaired polymers showed excellent thermal properties. The glass transition temperatures of these polymers are in the range of 251–274?°C under nitrogen atmosphere. The decomposition temperature in nitrogen for a 10% weight-loss temperature is more than 744?°C, and char yield at 900?°C ranged from 43 to 56% in nitrogen. Water contact angles were also tested to know the hydrophilicity of the polyamide films. As-synthesized polyamides showed smallest quantact angles indicating hydrophilic surface.     

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.     

Organo-soluble and transparent polyimides containing phenylphosphine oxide and trifluoromethyl moiety: Synthesis and characterization

A series of aromatic polyimides (PI-II_a-d) containing lateral phenylphosphine oxide (PPO) and trifluoromethyl (-CF₃) moiety were prepared from an aromatic diamine, 2,5-bis[(4-amino-2-trifluoromethylphenoxy)phenyl]diphenyl-phosphine oxide (BATFDPO) and various aromatic dianhydrides via a two-step chemical imidization procedure. In parallel, for comparison, another series of polyimides (PI-I_a-d) without trifluoromethyl were synthesized from a diamine, 2,5-bis[(4-aminophenoxy)-phenyl]diphenylphosphine oxide (BADPO) and the same dianhydrides. It was found that both of the two series of polyimides (PIs) were soluble in polar aprotic solvents, such as N-methyl-2-pyrrolidinone (NMP) and the solubility of PI-II_a-d was highly enhanced by the introduction of the bulky -CF₃ group. Flexible and tough PI films with tensile strengths higher than 70 MPa were cast from the PI solution. The introduction of -CF₃ moiety slightly sacrificed the thermal stability and mechanical properties of the PI films. For example, PI-II_a-d showed 5% weight loss at 472-476 ^°C, which was about 50 ^°C lower than those of their PI-I_a-d analogues. However, -CF₃ group apparently improved the optical transparency and decreased the refractive indices of the PI films. PI-II_d derived from BATFDPO and 4,4’-hexafluoroisopropylidenediphthalic anhydride (6FDA) exhibited the highest optical transparency with the transmittance of 90% at 400 nm and the refractive index as low as 1.5511 at 1310 nm.     

Wholly aromatic chiral polyamides bearing pendant phthalimido and L-isoleucine moities

<正>A potential biodegradable and optically active bulky chiral aromatic amide-imidic diacid monomer,(2S,3S)-5-(3- methyl-2-phthalimidylpentanoylarnino)isophthalic acid(7),containing a rigid phthalimide and flexible L-isoleucine pendant group was synthesized in three steps.New aromatic polyamides including pendant phthalimido groups and flexible side spacers have been synthesized by direct polycondensation reaction of equimolar amounts of different aromatic diamines with an optically active diacid 7,using N-methyl-2-pyrrolidone(NMP) as a solvent and triphenyl phosphite/CaCl_2/pyridine as a condensing agent.These polyamides were characterized by FTIR,~1H-NMR spectroscopy,specific rotation, thermogravimetric and elemental analysis.The resulting polymers have inherent viscosities in the range of 0.21-0.45 dL/g. Amino acid existence in this backbone results in optically active polymers.Due to introduction of bulky and flexible groups in these polyamides,they show improved solubility in polar aprotic solvents such as NMP and dimethylacetamide and also good thermal stability(10%weight loss temperatures in excess of 330℃,and char yields at 600℃in nitrogen higher than 62%).     

Synthesis and properties of a novel polyester containing bithiazole

A novel Schiff base type polyester containing 2,2’-diamino-4,4’-bithiazole(DABT) was prepared by low-temperature interface polycondensation of 1,4-benzenedicarbonyl dichloride with 4,4’-(4,4’-bithiazole-2,2’-diylbis(imine-2,1-diyl)diphenol(BDDP), which is derived from a 2,2’-diamino-4,4’-bithiazole(DABT) Schiff base reacted with a 4-hydroxybenzaldehyde monomer.The newly generated polyester was evaluated based on characterization of its solubility,FTIR spectroscopy,elemental analysis,X-ray diffraction measurements and thermogravimetric analysis(TGA) studies.     

左旋多巴胺Schiff碱的合成,表征和抗菌活性

近来,资料表明Schiff碱作为相转移催化烷基化的良好中间体,在药物合成、催化、分析化学等领域有着重要应用。Schiff碱及其衍生物与金属形成的配合物具有抑菌、杀菌、抗肿瘤、抗病毒等多方面的生物活性,在医学领域有广泛的应用前景[1,2]。本文利用广西丰富的天然资源左旋多巴为原料,与芳香醛酮反应,合成并表征了8种左旋多巴胺Schiff碱(其中4-硝基苯甲醛、香兰醛、4-氯苯甲醛、肉桂醛、大茴香醛及水杨醛缩多巴胺Schiff碱未见文献报道),并研究它们对金黄色葡萄球菌、大肠杆菌的体外抑菌活性。1实验部分1·1药口和试剂硅胶GH254、硅胶H(200-3…