Synthesis,characterization, optical,thermal and electrical properties of polybenzimidazoles

The variation of dielectric constant and dielectric loss of two novel polybenzimidazole (PBI) were studied at constant temperature with variable frequency. The polymers have shown maximum dielectric constant at low applied frequency 50 Hz at 393 K due to the space charge polarization. The AC conductivity and activation energy of polymers were arrived from dielectric constant and dielectric loss values. PBIs were synthesized by the oxidative polycondensation of benzimidazole monomers, 2-(1H-benzo [d] imidazole-2-yl)-4-bromophenol (BIBP), and 2-(1H-benzo [d] imidazole-2-yl)-6-methoxyphenol (BIMP) in an aqueous alkaline medium using NaOCl as oxidant. The monomers and polymers were characterized by various spectroscopic techniques. Fluorescence spectra of monomers and polymers showed their λ _max emission in the region of 472–479 and 463–472 nm respectively. The electrical conductivities of iodine doped polybenzimidazoles were measured by four-point probe technique and it increases with increase in iodine vapour contact time. The electrical conductivity values were correlated with the charge density on imidazole nitrogen obtained from Huckel calculation method. Both the PBI are having reasonably good thermal stability and are shown by high carbines residues of around 40% at 500°C in thermogravimetric analysis.     

Synthesis and characterization of new type molecular wires with tetrathiafulvalene as redox center

A new type of molecular wire 1a – c with tetrathiafulvalene (TTF) units was synthesized and characterized. The UV–vis spectra and electrochemistry results showed that comparing with PPE, these polymers had smaller HOMO–LUMO band gap, and the HOMO level of polymer 1a (?5.05 eV) was closer to the work function energy of Au electrode. Thermal stability analyses indicated that these polymers had good thermal stability. All of the results showed that the introduction of TTF units made polymers 1a – c better candidates for molecular wires than PPE. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2707–2713, 2006     

Synthesis,characterization and antimicrobial activity of maltol functionalized chitosan derivatives

Chitin was isolated from prawn shell powder through demineralization and deproteinization process. Chitosan was synthesized from isolated chitin by deacetylation process and characterized by Fourier Transform Infrared (FTIR) spectra which showed close agreement with commercial chitosan. Physicochemical features such as moisture content, ash content, degree of deacetylation and molecular weight has been measured. The prepared chitosan was found to have comparatively higher molecular weight than the commercial chitosan. Functionalization of NH₂ group of chitosan with C?=?O group of maltol and ethyl maltol by refluxing equimolar quantities of respective ketones was performed. These synthesized derivatives of chitosan were characterized by their FTIR, ¹³C-Nuclear magnetic resonance (NMR) spectroscopy, elemental analysis, X-Ray Diffraction (XRD), Thermogravimetric analysis (TGA) and Differential thermal analysis (DTA) instrumental techniques. Antibacterial screening results of the synthesized chitosan and its derivatives indicate that these compounds are active against Escherichia coli bacteria.     

Novel poly(pyridine imide) with pendent naphthalene groups: Synthesis and thermal,optical, electrochemical,electrochromic, and protonation characterization

A new diamine containing a pyridine heterocyclic group and a naphthalene substituent, 4-(2-naphthyl)-2,6-bis(4-aminophenyl) pyridine (NBAPP), was synthesized with the Chichibabin reaction and used in the preparation of poly(pyridine imide) by direct polycondensation with 4,4′-hexafluoroisopropylidenediphathalic anhydride in N-methyl-2-pyrrolidinone (NMP). The poly(pyridine imide) derived from diamine NBAPP with naphthalene substituents was highly organosoluble: it was soluble in tetrahydrofuran, NMP, N,N-dimethylacetamide (DMAc), N,N-dimethylformamide, and γ-butyrolactone at room temperature and in pyridine, dimethyl sulfoxide, and cyclohexanone upon heating at 70 °C. The poly(pyridine imide) was converted into lightly colored, optically transparent, flexible, and tough polyimide films via casting onto glass from a DMAc solution. This polymer exhibited good thermal stability (temperature of 10% weight loss = 527 °C) in air and high dielectric constants (as high as 4.20 at 1 kHz). The polyimide films had a tensile strength of 102 MPa and a tensile modulus of 1.8 GPa. As for the optical properties, the polymer exhibited UV–vis absorption bands in the region of 223–450 nm and possessed strong green-yellow fluorescence (500 nm) after being protonated with acid. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 2367–2374, 2007     

两亲性四硫富瓦烯衍生物的合成及其性质研究

二-(1,3-二硫环戊烯-2-硫酮-4,5-二硫)合锌酸四乙基铵盐(Zincate盐)分别与溴代十四烷和溴代十八烷在乙腈中回流,合成相应的1,3-二硫环戊烯-2-硫酮2a和2b.以亚磷酸三乙酯为偶联剂,其分别和4,5-二氰基乙硫基-1,3-二硫环戊烯-2-酮(3)发生交叉偶合反应合成四硫富瓦烯(TTF)衍生物4a和4b.在氢氧化铯的存在下,4a和4b分别与2-碘乙氧基乙醇反应生成含羟基的四硫富瓦烯(TTF)衍生物5a和5b.以三乙胺为缚酸剂,其与对甲基苯磺酰氯反应,生成含活化羟基的TTF衍生物6a和6b.在氢氧化钠的存在下,6a和6b分别与巯基噻二唑反应生成含有疏水长链烷烃和亲水醚键连接的噻二唑两亲性TTF衍生物7a～7d,并对其进行了1H NMR,13C NMR,IR,MS的表征以及初步电化学行为和Langrnuir-Blodgett膜性能研究.     

新型四硫富瓦烯-杯芳烃衍生物的合成与其电化学行为

在高度稀释条件下, 溴烷基化杯[4]芳烃1a和1b分别与二-(1,3-二硫杂环戊烯-2-硫酮-4,5-二硫)合锌酸四乙基铵盐在乙腈中回流, 得到含杯[4]芳烃单元的硫酮2a和2b. 以亚磷酸三乙酯为偶联剂, 其分别和4,5-二腈基乙硫基-1,3-二硫代环戊烯-2-酮发生交叉偶合反应, 合成了两个新颖的四硫富瓦烯–杯[4]芳烃衍生物3a和3b, 并对其进行了结构表征和电化学行为研究. 同时用X射线衍射法确认了2b的晶体结构.     

Novel aromatic polymers from benzaldehyde and triphenylamine derivatives: Synthesis,electrochromic, and photochemical properties

A series of novel triphenylamine‐based polymers were synthesized from benzaldehyde and triphenylamine derivatives. All the polymers having high molecular weight are readily soluble in many organic solvents and could be solution‐cast into amorphous films. They had glass transition temperatures (T_gs) in the range of 193–217 °C, and 10% weight loss temperatures in excess of 475 °C. Cyclic voltammograms of all polymers showed reversible oxidation redox peaks and E_onset around 0.42–0.90 V, indicating that the polymers are electrochemically active and stable. In addition, all these polymers revealed photochemical characteristics in conformity with their electrochromic characteristics. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 2118–2131, 2009     

Synthesis and characterization of functionalized water soluble cationic poly(ester amide)s

A new family of positively charged, water soluble and functional amino acid‐based poly(ester amide)s ( Arg‐AG PEA ) consisting of four building blocks (L ‐Arginine, DL ‐2‐Allylglycine, oligoethylene glycol, and aliphatic diacid) were synthesized by the solution copolycondensation. Functional pendant carbon–carbon double bonds located in the DL ‐2‐allylglycine unit were incorporated into these Arg‐AG PEAs, and the double bond contents could be adjusted by tuning the feed ratio of L ‐arginine to DL ‐2‐allylglycine monomers. Chemical structures of this new functional Arg‐AG PEA family were confirmed by Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR) spectra. The thermal property of these polymers was investigated; increasing the methylene chain in both the amino acid and diacid segments resulted in a reduction in the polymer glass‐transition temperature. All these cationic Arg‐AG PEAs had good solubility in water and polar organic solvents. The cytotoxity of Arg‐AG PEAs was evaluated by 3‐(4,5‐Dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide (MTT) assay. These preliminary MTT results indicated that Arg‐AG PEAs were nontoxic to bovine aortic endothelial cells (BAECs). © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3758–3766, 2010     

Synthesis,characterization, and metal uptake of multiple functionalized immobilized-polysiloxane diamine-thiol chelating ligand derivatives

Immobilized-polysiloxane (diamine-thiol) tetraethylacetate, P-(NN-S)-TEA (where P represents [Si–O]_n polysiloxane network), was synthesized using one-pot reaction of tetraethylorthosilicate (TEOS) with 3-(ethylenediaminetriethylacetate)propyltrimethoxysilane and 3-thiolethylacetatepropyltrimethoxysilane in the presence of cetyl trimethylammonium bromide (CTAB) as a surfactant. Its ethylenediamine and diethylenetriamine modified polysiloxane (diamine-thiol)-tetrakis(N-2-aminoethylacetamide), P-(NN-S)-TEA-NN, and polysiloxane (diamine-thiol)-tetrakis(N-diethylenediamineacetamide), P-(NN-S)-TEA-NNN chelating ligand systems were also obtained. Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopic (XPS), and thermogravimetric analysis (TGA) techniques have been used for establishing their structures. An elemental CHNX combustion analyzer was used to determine the mass fractions of carbon, hydrogen, nitrogen, and sulfur of samples. The metal uptake capacities results showed that the modified polysiloxane ligand systems exhibited high capacities for the uptake of divalent metal ions in the following order: Cu²⁺> Pb²⁺> Ni²⁺> Co²⁺.     

Synthesis,characterization, and physical properties of two novel nonaheteroacene derivatives

Two novel nonaheteroacene derivatives: 24,27,30,33-tetra-tert-butyl-6,8,10,17,19,21-hexaaza-1.22,4.5,11.12,15.16-tetrabenzono-nonaacene (1) and 24,27,30,33-tetra-tert-butyl-6,10,17,21-tetraaza-8,19-benzodioxin-1.22,4.5,11.12,15.16-tetrabenzono-nonaacene (2), have been successfully synthesized through cyclocondensation reactions. The studies on UV–vis and cyclic voltammogram suggest that compound 1 has a smaller bandgap comparing to that of compound 2, indicating that oxygen atoms can destroy the conjugation in compound 2. The results are further confirmed by theoretical simulation.     

Synthesis,characterization and X‐ray shielding properties of polypyrrole/lead nanocomposites

Novel radiation shielding nanocomposites based on a conducting polymer were fabricated and investigated to determine their abilities in attenuation of X‐rays. Polypyrrole/Pb nanocomposites were prepared through chemical reduction of lead salt by a facile solution‐phase method using t‐BuOLi‐activated LiH and in situ chemical polymerization of pyrrole in the presence of dodecyl benzene sulfonic acid as dopant and surfactant and iron chloride as the oxidant. The morphology, composition, and electrical conductivity of resulting products were characterized by scanning electron microscopy, transmission electron microscopy, X‐ray diffraction analysis, energy‐dispersive X‐ray spectroscopy, fourier transform infrared spectroscopy, and standard four‐wire technique, respectively. In order to evaluate capability of nanocomposites in radiation shielding, X‐ray photon interaction parameters such as linear attenuation coefficient, attenuation percentage, and half‐value thickness were determined for the samples with different Pb loadings and thicknesses, at photon energies of 13.95, 17.74, 20.08, 26.34, and 59.50 keV. The investigation was carried out to explore the potential of polypyrrole/Pb nanocomposites as thin and light‐weight radiation shielding materials. Copyright © 2015 John Wiley & Sons, Ltd.     

Synthesis and characterization of benzimidazolium‐functionalized polysulfones as anion‐exchange membranes

Anion‐exchange membranes containing pendant benzimidazolium groups were synthesized from polysulfone by chrolomethylation followed by nucleophilic substitution reaction with 1‐methylbenzimidazole. The structures of the polymers were characterized by ¹H‐NMR and FTIR analysis. The resulting membranes showed high thermal stability below 200 °C. The values of water uptake and swelling degree increased with the ion‐exchange capacity of the polymeric membrane. The ionic conductivity was measured by means of impedance spectroscopy in aqueous solution of potassium hydroxide (10^?4?10^?1 M). The results show not only a clear correlation between the membrane's electrochemical behavior with the electrolyte solution embedded in the membrane, but also with the degree of the polysulfone's chloromethylation.Thus, the ionic conductivity increased more than two orders of magnitude when the degree of chloromethylation increased from 40 to 140%. Benzimidazolium‐functionalized polysulfones exhibited better thermal, mechanical, and electrochemical properties than the widely used polymeric membranes containing quaternary ammonium groups. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 2363–2373     

New cyclen-cored dendrimers functionalized with pyrene: Synthesis characterization,optical and photophysical properties

New cyclen (1,4,7,10-teraazacyclododecane) cored dendrimers up to the second generation, functionalized with 4, 8 and 16 pyrene units, respectively, were synthesized following a convergent procedure. All new compounds were characterized by NMR spectroscopies and ESI or MALDI TOF mass spectrometry. The optical and photophysical properties of the new dendrimers were studied in THF solution. Absorption spectra showed the typical absorption bands of pyrene moieties. In the fluorescence spectra, monomer as well as excimer emission were observed for all compounds. An increased proportion of excimer emission was observed in the dendrimer of the highest generation.     

Synthesis and characterization of high-barrier polyimide containing rigid planar moieties and amide groups

A high-performance polyimide was prepared by the dipolymerization of 4,4'-diaminobenzanilide (DABA) and pyromellitic dianhydride (PMDA). Due to the introduction of rigid planar moieties and amide groups, the polyimide shows outstanding properties, such as high glass transition temperatures (435 °C), excellent thermal stability (T_d5%, 542 °C, coefficient of thermal expansion, −3.2 ppm K⁻¹), and superior mechanical properties. Most importantly, the polyimide exhibits excellent barrier properties, with oxygen transmission rate (OTR) and water vapor transmission rate (WVTR) low to 7.9 cm³ (m² day)⁻¹ and 5.1 g (m² day)⁻¹, respectively. Wide angle X-ray diffractograms (WAXD), positron annihilation lifetime spectroscopy (PALS) and molecular dynamics simulations reveal that the excellent barrier properties are mainly attributed to the high crystallinity, high extent of in-plane crystalline orientation, and low free volume, which are resulted from the rigid planar structure and strong interchain hydrogen bonding. The high-barrier and thermally stable polyimide has an attractive potential application prospect in the fields of micro-electronics encapsulation and high grade packaging industry.     

Synthesis, characterization and electrical conductivity of poly [ethyl trifluorobuty-2-noate]

Poly[ethyl trifluorobuty-2-noate] (PETFB) was prepared from ethyltrifluorobuty-2-noate by anionic polymerization.The polymer was examined by UV-Vis,IR and NMR spec-trometries.It possessed π-conjugated backbone in the main chain.No significant variation in the electrical conductivity of BF3-doped PETFB was observed after more than three months' storage,indicating improved conductive stability in air as compared with polyacetylene.     

非对称双稠合四硫富瓦烯衍生物的合成与表征

采用W itting偶合反应合成了两种非对称双稠合四硫富瓦烯衍生物:2-(4,′5′-二乙硫基-1,′3′-二硫代环戊烯-2′-叉)-5-(4,′5′-二腈乙硫基-1,′3′-二硫代环戊烯-2′-叉)-1,3,4,6-四硫并环戊烯(7a)和2-(4,′5′-二丁硫基-1,′3′-二硫代环戊烯-2′-叉)-5-(4,′5′-二腈乙硫基-1,′3′-二硫代环戊烯-2′-叉)-1,3,4,6-四硫并环戊烯(7b)。7a在室温下呈现半导体状态(σ=2.17×10-7s.cm-1),而7b是绝缘体。通过UV-vis,1H NMR,IR和元素分析对产物及中间产物的结构进行了鉴定及讨论,从而验证了合成路线的可行性。     

Cu-incorporated mesoporous materials: Synthesis, characterization and catalytic activity in phenol hydroxylation

A series of novel Cu-incorporated mesoporous materials (CMMs) with molar ratios of Cu/Si ranging from 1/200 to 1/20 were synthesized by sol–gel method using glutaric acid as template. The materials were characterized by powder X-ray diffraction (XRD), N₂ adsorption, diffuse reflectance UV–vis spectroscopy and transmission electron microscopy (TEM). The results indicate that the CMMs have a three-dimensional (3D) worm-like mesoporous structure with a surface area between 600 and 800 m² g⁻¹ and the copper ions are incorporated into the matrix with octahedral environment. The catalytic activity of these CMMs in the phenol hydroxylation using H₂O₂ as oxidant is comparable to that of TS-1. Effects of Cu/Si molar ratio in the catalyst and the influence of various reaction parameters on the catalytic activity were investigated in detail and the optimized reaction condition was acquired.     

Synthesis and properties study of novel ferrocenyl isoxazole derivatives

A synthetic procedure based on the 1,3‐dipolar cycloaddition reactions of nitrile oxides and ethynylferrocene derived from ferrocene has been developed to synthesize new ferrocenyl‐isoxazole derivatives. The stable solids were thoroughly characterized by ¹H NMR, FT‐IR, and mass spectroscopy. The structure of (η⁵‐C₅H₅) Fe (η⁵‐C₅H₄) C₃HNOC₆H₄CH₃ was determined by single‐crystal X‐ray diffraction. The electrochemical behaviors of the synthesized ferrocenyl‐isoxazole derivatives were also studied. Copyright © 2005 John Wiley & Sons, Ltd.     

One-pot synthesis of new functionalized azacryptands from resorcinol derivatives for advanced photonic materials

Functionalized azacryptands containing resorcinol derivatives such as orcinol (5-methylresorcinol), 3,5-dihydroxybenzoic acid (5-carboxyresorcinol), and methyl 3,5-dihydroxybenzoate (5-methoxycarbonylresorcinol) were synthesized by one-pot synthesis in the presence of potassium carbonate with moderately good yields for advanced photonic materials, such as optical amplifying and light-emitting materials, for the first time to our knowledge.