Synthesis,characterization, and study of thermal properties of methyl-substituted arylene sulfone ether polyimides,polyamides, and poly(amide–imides)

A number of methyl-substituted bis[(phenyleneoxy) sulfone] dianilines were synthesized and reacted with pyromellitic dianhydride (PMDA), benzophenone tetracarboxylic acid dianhydride (BTDA), terephthaloyl chloride (TPC), isophthaloyl chloride (IPC), and trimellitic anhydride acid chloride (TMAC) to prepare a series of polyimides, polyamides, and poly(amide–imides), respectively. Low temperature solution and interfacial polymerization techniques were utilized to prepare the above polymers. Most of the polymers prepared formed tough, transparent flexible films. The prepared polymers were characterized by solution viscosity, thermal gravimetric analysis (dynamic and isothermal), and differential scanning calorimetry. The effect of the number and the ring substitution of methyl groups on polymer properties is discussed.     

Synthesis of substituted poly (arylene vinylene) films by vapor deposition polymerization

Summary An efficient method for the synthesis of PPV based polymers, poly ( 2,5-dimethyl-1,4-phenylene vinylene) (DMe-PPV) and poly (2,5-dimethoxy-1,4-phenylene vinylene) (DOMe-PPV) were developed using 2,5-dimethyl-1,4-bis ( chloromethyl ) benzene and 2,5-dimethoxy 1,4-bis ( chloromethyl ) benzene via vapor phase pyrolysis and followed by vapor deposition polymerization. The structure of polymer films were confirmed by FT-IR, solid state NMR and elemental analysis. Thermal gravimetry analysis reveals that the precursor polymer films form a conjugated polymer after thermal conversion at 250°C. The optical and electrical properties of the polymer films were investigated by UV-Vis absorption and photoluminescence spectroscopies. Electroluminescent devices were fabricated using these polymers. Received: 18 May 2000/Revised version: 21 July 2000/Accepted: 28 July 2000     

Photo-oxidative coupling polymerization of methoxy acetonitrile and thermal behavior of the polymer obtained

Photo-oxidative coupling polymerization of methoxy acetonitrile was carried out by using organic peroxide as an oxidizing agent under UV light irradiation at ambient temperature. The acetonitrile gave a homopolymer with a molecular weight of about 1000-1600 in moderate yield. ¹H-NMR and ESR spectra demonstrated the production of the polymer with the structure of 1,1-disubstituted polymethylene through a methoxycyanomethyl radical intermediate. It was also found that the polymer easily produced unpaired electrons in the structure only by heating and it initiated the polymerization of methyl methacrylate above 70°C. In addition, the acetonitrile also afforded a copolymer with diphenylmethane by the coupling polymerization.     

2-乙烯基-2-噁唑啉的合成及聚合

通过亚氨酸酯合成了２ 乙烯基 ２ 口恶唑啉（ＶＯＺＯ）单体。对合成过程中的溶剂及分离等问题进行了讨论。ＶＯＺＯ在苯溶液中自由基聚合生成聚乙烯基口恶唑啉（ＰＶＯＺＯ）。用元素分析和红外光谱表征的方法,证实了所得单体和聚合物的分子结构;发现聚合物ＰＶＯＺＯ为分子中仍保有口恶唑啉环侧基的对水和有机溶剂都有着良好溶解性的线型大分子。     

Mechanism research of copper(II)-catalyzed polymerization of 2,4,6-trichlorophenols

The copper(II)-catalyzed polymerization of 2,4,6-trichlorophenol and 2,4,6-trichloro-3-methylphenol were studied. Their polymer structures were confirmed by elemental analysis, infrared (IR), and nuclear magnetic resonance (NMR). The 2,4,6-trichlorophenoxo–copper(II) complex and 2,4,6-trichloro-3-methylphenoxo–copper(II) complex intermediates were isolated. The elemental analysis and electron spin resonance (ESR) measurement of the phenoxo–copper(II) complexes were discussed in relation to their structures. Decomposition of the phenoxo–copper(II) complex in refluxing benzene yielded poly(dichlorophenylene oxide). ESR measurements on the phenoxo–copper(II) complex in the solid state at 120°C indicated that the phenoxy radical was generated during the period of decomposition and the intensity of the ESR spectra based on the copper(II) ion decreased with the measurement time. A single-electron transfer reaction mechanism was proposed for the phenoxo–copper(II) complex intermediate. © 1996 John Wiley & Sons, Inc.     

Cohesive Zone Models of Polyimide/Aluminum Interphases

The fracture energy required to delaminate PMDA/ODA polyimide films from aluminum substrates was determined using the circular blister test. Films were prepared by spin coating the polyamic acid of PMDA and ODA onto polished aluminum substrates, by vapor co-deposition of PMDA and ODA monomers onto polished aluminum substrates, or by spin-coating the polyamic acid onto polished aluminum substrates that were first coated with thin layers of γ-aminopropyltriethoxysilane (γ-APS). Elastic and elastoplastic analyses were used to extract the fracture energies from the blister test results. Elastoplastic analysis provided fracture energies that ranged from 579 J/m² for spin-coated films on polished substrates to 705 J/m² for vapor-deposited films on polished substrates and to 750 J/m² for spin-coated films on silanated substrates. These values were intermediate between those provided by the two different elastic analyses. Differences in fracture energy determined by the three different analysis methods were related to plastic deformation in the films and, in the case of the two elastic analyses, to differences in the approach used to extract the fracture energy from experimental results. Failure of specimens prepared by spin-coating PMDA/ODA films onto aluminum substrates occurred cohesively within the polymer, near the interface between well imidized polymer in the bulk of the films and poorly imidized polymer in a layer near the aluminum surface. For the case of specimens prepared by vapor codeposition of PMDA and ODA monomers, failure occurred within the vapor deposited films, close to the aluminum/film interface. Failure of spin-coated films on silanated substrates occurred mostly within the γ-APS but leaving 'islands' of polyimide and silane on the aluminum.     

Cohesive Zone Models of Polyimide/Aluminum Interphases

The fracture energy required to delaminate PMDA/ODA polyimide films from aluminum substrates was determined using the circular blister test. Films were prepared by spin coating the polyamic acid of PMDA and ODA onto polished aluminum substrates, by vapor co-deposition of PMDA and ODA monomers onto polished aluminum substrates, or by spin-coating the polyamic acid onto polished aluminum substrates that were first coated with thin layers of γ-aminopropyltriethoxysilane (γ-APS). Elastic and elastoplastic analyses were used to extract the fracture energies from the blister test results. Elastoplastic analysis provided fracture energies that ranged from 579 J/m² for spin-coated films on polished substrates to 705 J/m² for vapor-deposited films on polished substrates and to 750 J/m² for spin-coated films on silanated substrates. These values were intermediate between those provided by the two different elastic analyses. Differences in fracture energy determined by the three different analysis methods were related to plastic deformation in the films and, in the case of the two elastic analyses, to differences in the approach used to extract the fracture energy from experimental results. Failure of specimens prepared by spin-coating PMDA/ODA films onto aluminum substrates occurred cohesively within the polymer, near the interface between well imidized polymer in the bulk of the films and poorly imidized polymer in a layer near the aluminum surface. For the case of specimens prepared by vapor codeposition of PMDA and ODA monomers, failure occurred within the vapor deposited films, close to the aluminum/film interface. Failure of spin-coated films on silanated substrates occurred mostly within the γ-APS but leaving ‘islands’ of polyimide and silane on the aluminum.     

A study of the adhesion of thiokol-epoxy hermetics to a brass and an aluminum alloy substrate

The conditions under which hermetics can be used depend largely on the nature of the bond between the polymer and the substrate. Here we have studied the thiokol-epoxy compositions and have investigated the processes taking place at the interface between the hermetic and a brass or an aluminum alloy substrate. To establish the nature of interfacial interactions electron spin resonance (ESR) spectroscopy was utilized. The ESR spectrum of the species from the interface layer is assigned to a bivalent copper ion complex, sulfur-containing fragments being the ligands. The ESR signal intensity of the complex was maximum for the case of the brass substrate and minimum for the aluminum alloy substrate; no spectrum was detected for the glass substrate or for the bulk hermetic. The dependence of the ESR signal intensity on the free sulfur content in the hermetic was found to be opposite to the dependence of the adhesion values.     

Asymmetric Flexible Supercapacitor Stack

Electrical double layer supercapacitor is very significant in the field of electrical energy storage which can be the solution for the current revolution in the electronic devices like mobile phones, camera flashes which needs flexible and miniaturized energy storage device with all non-aqueous components. The multiwalled carbon nanotubes (MWNTs) have been synthesized by catalytic chemical vapor deposition technique over hydrogen decrepitated Mischmetal (Mm) based AB₃ alloy hydride. The polymer dispersed MWNTs have been obtained by insitu polymerization and the metal oxide/MWNTs were synthesized by sol-gel method. Morphological characterizations of polymer dispersed MWNTs have been carried out using scanning electron microscopy (SEM), transmission electron microscopy (TEM and HRTEM). An assymetric double supercapacitor stack has been fabricated using polymer/MWNTs and metal oxide/MWNTs coated over flexible carbon fabric as electrodes and nafion^® membrane as a solid electrolyte. Electrochemical performance of the supercapacitor stack has been investigated using cyclic voltammetry, galvanostatic charge-discharge, and electrochemical impedance spectroscopy.     

Synthesis of poly(arylene disulfide)–vermiculite nanocomposites via in situ ring‐opening polymerization of macrocyclic oligomers

Exfoliated poly(4, 4′‐oxybis(benzene)disulfide)/vermiculite (POBDS/VMT) nanocomposites were successfully synthesized via in situ melt intercalation of cyclo(4, 4′‐oxybis(benzene)disulfide) oligomers (COBDS) into octadecylammonium‐exchanged VMT (organo‐VMT). The POBDS/VMT nanocomposites were melt fabricated in a two‐step process. First, the COBDS/VMT nanocomposite precursor was fabricated by melt delaminating organo‐VMT with COBDS at a temperature slightly higher than its melting point. Subsequently, exfoliated POBDS‐VMT nanocomposites can be prepared in situ via instant melt ring‐opening polymerization of the COBDS‐VMT nanocomposite precursor. The nanoscale dispersion of VMT layers within POBDS polymer was confirmed by X‐ray diffraction, scanning electron microscopy and transmission electron microscopy. High molecular weight POBDS polymer was formed in a few minutes at the same time as the nanocomposite formation. The results of dynamic mechanical analysis showed that the storage modulus and glass transition temperature of the nanocomposites are much higher than those of the POBDS matrix, even with a very small amount of VMT addition. This methodology provides a potential approach to synthesize high‐performance polymer/clay nanocomposites. Copyright © 2004 Society of Chemical Industry     

Mechanism and kinetics of the free radical ring-opening polymerization of cyclic allylic sulfide lactones

The polymerization of 7-, 8- and 11-membered lactones, 6-methylene-1,4-oxathiepan-7-one, 3-methylene-1,5-oxathiocan-2-one and 3-methylene-1-oxa-5-thiacycloundecan-2-one in benzene at 70, 40–70 and 40–65 °C, respectively, is presented. All polymerizations proceeded with complete ring-opening up to approximately 25% conversion, where insoluble polymer was formed. Evidence is given attributing polymer double bond loss to crosslinking, although redistribution of the molecular weights via addition to polymer double bonds followed by β-fragmentation also appears to occur for polymerizations of the 8- and 11-membered lactones. Michael adducts of lactones with 2-methyl-2-propanethiol were prepared as models for chain-transfer products of hydrogen abstraction by carbon-centred radicals. Polymerization rates were found to increase marginally with ring size. Arrhenius parameters obtained for the polymerizations of the 8- and 11-membered lactones indicated that the addition step was more important than fragmentation in determining the rate of propagation.     

In situ deposition of poly(1,8-diaminonaphthalene): from thin films to nanometer-sized structures

Chemical in situ deposition of poly(1,8-diaminonaphthalene) (p(1,8-DAN)) on conductive supports in aqueous and acetonitrile solutions was investigated using electrochemical quartz crystal microbalance (EQCM) and UV-vis spectroscopy. The resulting deposits were examined by the means of cyclic voltammetry (CV), FT-IR and Raman spectroscopy. P(1,8-DAN) was also deposited via chemical polymerization onto a porous polycarbonate membrane (PC) which served as a template for synthesis of nanometer-sized structures. The deposits of p(1,8-DAN) on PC substrate were imaged by atomic force microscopy (AFM) and the nanostructures obtained by dissolution of the template were visualized by scanning electron microscopy (SEM). The EQCM and UV-vis studies indicated that the polymer is formed both on the surface of the substrate and in the bulk of the polymerization solution. However, polymerization of 1,8-DAN in solution is delayed in comparison with deposition on the substrate. Electrochemical and spectroscopic properties of p(1,8-DAN) formed chemically closely resemble the properties of the electrosynthesized polymer. Furthermore, SEM images of p(1,8-DAN) nanostructures revealed that the polymer nanowires are formed in aqueous solutions, whereas two types of structures: nanowires and round shaped structures, not fitting to the pore size, can be obtained by chemical polymerization in the acetonitrile medium.     

H-bonding assisted template synthesis of a novel ladder-like organo-bridged polymethylsiloxane

A novel soluble aryl amide-bridged ladder-like polymethylsiloxane (ALPS) was synthesized via a stepwise coupling polymerization by means of H-bonding self-assembling template. The new monomer N,N′-di(4-methyldiethoxysiloxyl-phenyl)-terephthaloyl amide, prepared by dehydrocoupling reaction of N,N′-di(4-hydroxy-phenyl)-terephthaloyl amide with methyldiethoxysilane, was hydrolyzed in a dilute solution at low temperature to form a proposed ladder-like supramolecular intermediate through amido H-bonding interaction, which was further condensed to form polymer ALPS using dibuthyltindilaurate as catalyst. A combination of techniques including ¹H NMR, ²⁹Si NMR, FTIR, X-ray diffraction (XRD), DSC, and light scattering were used to characterize the titled polymer ALPS. The results indicate the polymer ALPS possesses an ordered ladder-like architecture.     

溶液电沉积法制备苝酰亚胺类化合物薄膜

溶液电沉积法是一种具有沉积时间短,可以常温沉积以及沉积物在基底上附着力高等优点的薄膜制备方法.本文用水合肼增溶苝酰亚胺类化合物(PTCDI)的方法制备了可用于溶液电沉积的苝酰亚胺类化合物溶液.用紫外-可见分光光度法(UV-Vis)对溶解的过程进行了表征,并用顺磁共振(ESR)验证了水合肼对PTCDI的增溶过程实质上是化学反应过程.在制备苝酰亚胺类化合物溶液的基础上,采用阳极电沉积法在ITO导电玻璃上沉积出了薄膜.采用UV-Vis,扫描电镜(SEM)和X射线衍射仪(XRD)对薄膜进行了表征,证实得到了表面较为平整、具有可控结晶结构和形貌的PTCDI薄膜以及具有较宽光谱吸收范围的复合薄膜.     

Enhancement of adhesion between inorganic nanoparticles and polymeric matrix in nanocomposite by introducing polymeric thin film onto nanoparticles

Herein, we demonstrate an efficient pathway to improve both affinity and adhesion at interfaces between inorganic nanoparticles and organic polymer matrix by vapor phase incorporation of organic thin layers. The polymeric thin films with an average thickness of a few ～tens of nanometers were introduced onto the surface of inorganic nanoparticle by vapor deposition polymerization method. Diverse polymers such as vinyl polymers and conducting polymers can be coated on the surface of indium tin oxide (ITO) nanoparticles with a relatively simple method. The polymer‐coated ITO nanoparticles showed improved‐compatibility with polymer matrix in nanocomposite owing to the improved adhesion because of the presence of intermediate polymeric layer. POLYM. ENG. SCI., 55:1906–1911, 2015. © 2014 Society of Plastics Engineers     

The polymerization mechanism of lactide initiated with zinc (II) acetylacetonate monohydrate

The paper presents the mechanism of lactide polymerization initiated with zinc (II) acetylacetonate monohydrate. However, the actual initiator of this reaction is the complex containing a metal-oxygen bond, formed by the exchange reaction of acetylacetonate ligand with deprotonated lactide derivative. The described reaction results in the release of free acetylacetonate and formation of transitional zinc complex with metal-oxygen bond connecting the zinc atom with derivative of lactide, incorporated - as a new, active in polymerization ligand. Polylactide chain propagation process, which constitutes the following stage of the reaction, is caused by a typical, well known, coordination-insertion ring opening polymerization. The proceeding polymerization maximum yield at the applied conditions does not exceed about 70% in benzene solution and 90% at bulk.     

Electrochemical behaviour and electrochemical polymerization of fluoro‐substituted anilines

The electrochemical behaviour of three fluoro‐substituted aniline monomers, 2‐fluoroaniline (2FAN), 3‐fluoroaniline (3FAN) and 4‐fluoroaniline (4FAN), was investigated in aqueous acidic and organic media by means of cyclic voltammetry (CV) studies. Constant potential electrolysis (CPE) of the monomers in acetonitrile–water mixture (1:1 by volume) using NaClO₄ as supporting electrolyte yielded soluble polymers. The mechanism of electrochemical polymerization was investigated using in situ electron spin resonance (ESR) and in situ UV–VIS spectroscopic techniques for one of the monomers (4FAN). Both CV and in situ UV–VIS measurements indicated that the polymers obtained are in the emeraldine base form. In situ ESR studies indicated that electrochemical polymerization involves a radical‐cation as an intermediate. Characterization of polymer products have been carried out using FTIR and NMR spectroscopic techniques, and thermal behaviour was studied using differential scanning calorimetry (DSC). It was found that conductivity can be imparted to as‐synthesized polyfluoroanilines via iodine doping. © 2002 Society of Chemical Industry     

Copper/ polyimide interaction: A local spin density study

The interactions between a copper atom and various model molecules, phthalimide (PIM), PMDA and amino phenol (PAP), which represent well the functionalities of the polyimide PMDA-ODA, are studied using the quantum chemical local density functional (LDF) method. We found that Cu interacts preferentially with the PMDA's model molecules and less with the PAP. For the Cu/PIM and Cu/PMDA systems, four interaction sites have been investigated: the nitrogen atom, the phenyl ring, the five-membered imide ring, and the carbonyl group. The last site (C=O) was found to be the favored interaction site for Cu. The corresponding bond dissociation energy is 1.20 eV in both Cu/PMDA and Cu/PIM. In the case of Cu/PAP, the nitrogen and C-O bond sites have been investigated. The corresponding total energies differ only by 0.05 eV. The binding energy for Cu/PAP is 0.65 eV. Thus, the PMDA carbonyl group is the favored site for bonding with a Cu atom. As shown in our previous study on Cr/PMDA, Cr is more reactive than Cu and also interacts with the C=O group. Our results are in agreement with X-ray Photoelectron Spectroscopy (XPS) and Infra-Red Reflection Absorption Spectroscopy (IRRAS) measurements carried out on Cu/polyimide interfaces.     

Temperature‐sensitive membranes prepared by the plasma‐induced graft polymerization of N‐Isopropylacrylamide into porous polyethylene membranes

A temperature‐responsive polymer, poly(N‐isopropylacrylamide) (PNIPAAm), was grafted onto porous polyethylene membranes by a plasma‐induced graft polymerization technique. A wide range of grafting was achieved through variations in the grafting conditions, including the postpolymerization temperature, time, monomer concentration, and graft‐reaction medium. The active species induced by plasma treatment was proven to be long‐living via a postpolymerization time of 95 h. Different solvent compositions, that is, water, methanol, benzene, and water/methanol, were used as reaction media, and water showed a much higher polymerization rate than the organic solvents. Based on the hydrophilicity of the active species, a mechanism explaining the solvent effect in plasma‐induced graft polymerization was examined. Characterizations by scanning electron microscopy, X‐ray photoelectron spectroscopy (XPS), and micro Fourier transform infrared showed that the grafted polymers were located on both the outer surface and inside pores of the membranes. The XPS analysis also confirmed that the polar amide groups tended to distribute more outward when grafted PNIPAAm was in its expanding state than when it was in its shrinking state. Water permeation experiments showed that the permeability of the grafted membranes varied dramatically with a slight temperature change in the vicinity of the lower critical solution temperature (LCST) of PNIPAAm. The effective pore radii of the grafted membranes above and below the LCST could be depicted by Hagen‐Poiseuille's law. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 3180–3187, 2003     

Preparation and Characterization of Poly(benzimidazole-amide)/ZnO Nanocomposites Using Silane Coupling Agent

Some novel nanocompoites were fabricated via zinc oxide (ZnO) nanoparticles which was modified by 3-aminopropyltriethoxylsilane (KH550) as a coupling agent. Poly(benzimidazole-amide) (PBIA) was synthesized via polymerization reaction of 1,3-bis(5-amino-1H-benzimidazol-2-yl)benzene (3a) with isophthaloyl chloride (4b) and used as a polymer matrix. PBIA/ZnO nanocompoites were characterized by Fourier transform infrared spectra (FT-IR), X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and transmission electron microscopy (TEM). FE-SEM and TEM analysis showed that the modified ZnO nanoparticles were homogeneously dispersed in polymer matrix. In addition, thermogravimetric analysis (TGA) data indicated an enhancement of thermal stability of nanocomposite compared with the pure polymer.