A nanocomposite of poly(N‐vinylcarbazole) with nanodimensional alumina

A nanocomposite of poly(N‐vinylcarbazole) (PNVC) and Al₂O₃ was prepared by precipitation of a preformed PNVC in a tetrahydrofuran solution onto an aqueous suspension of nanodimensional Al₂O₃. Prolonged extraction of a PNVC–Al₂O₃ composite by benzene failed to extract the loaded PNVC from the Al₂O₃, as shown by Fourier transform infrared studies. Scanning electron microscopy analyses revealed distinct morphological features of the composite, and transmission electron microscopy analyses confirmed that the particle sizes were in the range of 120–240 nm. Thermogravimetric analyses demonstrated the enhanced stability of the nanocomposite relative to the base polymer. Direct current conductivity of the PNVC–Al₂O₃ composites was found to be about 0.14 × 10^?6 S/cm. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2233–2237, 2003     

Oxidative polymerization of N‐vinylcarbazole in polymer matrix

A new class of soluble conductive poly(N‐vinylcarbazole) (PVCz) compounds has been developed by oxidative matrix polymerization of N‐vinylcarbazole (NVCz) by Ce(IV) in the presence of poly(ethylene glycol) (PEG). PEG was found to be a more suitable matrix with which to obtain a stable homogenous ternary complex solution when compared with poly(acrylic acid) (PAA) and poly(vinylpyrrolidone) (PVP). The role of PEG, NVCz and Ce(IV) concentration, order of component addition, the structure of the polymer matrix, molecular weight of polymer and the effect of solvent have been investigated. Obtaining soluble PEG–Ce(III)–PVCz ternary complexes was shown by cyclic voltammetric measurements, and the initial rate of formation NVCz cation radicals as calculated using UV–visible spectrophotometry. Advantageously with these soluble complexes, conductivities could be measured both in solution and in the solid state. © 2001 Society of Chemical Industry     

Photophysical studies of copolymers of N‐vinylcarbazole

The absorption, fluorescence excitation and emission spectroscopy, and time‐dependent spectrofluorimetry have been used to study the photophysics of copolymers of N‐vinylcarbazole with different monomers like vinyl acetate, methyl acrylate, methyl methacrylate, butyl acrylate, and butyl methacrylate in dichloromethane. In all the copolymers and at different N‐vinylcarbazole content, the absorption spectra reflect only the monomer carbazole units. The two kinds of excited monomer species of N‐vinylcarbazole are present in S₁ state. Short‐lived (～3 ns) excited monomer decays forming low energy excimer obtained by the complete overlap of the excited carbazole monomer. The long‐lived excited monomer (～8 ns) decays to ground state without formation of any excimer. The high energy excimer is relatively short‐lived and is formed by the partial overlap of the carbazole units. The presence of bulky group in the copolymer chain hinders the formation of excimers. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 372–380, 2006     

A conducting composite based on poly(N‐vinylcarbazole)–formalin resin and acetylene black

A poly(N‐vinylcarbazole) (PNVC)–formalin (FO) resin (PNVC‐FO) was prepared via copolycondensation between N‐vinylcarbazole (NVC) and FO in the presence of dry HCl gas in toluene medium at 110°C. A highly conducting composite of PNVC‐FO resin with nanodimensional acetylene black (AB) was prepared by carrying out the polycondensation reaction in presence of a suspension of acetylene black (AB) in toluene. The inclusion of PNVC in the PNVC‐FO‐AB composite was confirmed by FT‐IR analysis. Scanning electron microscopic analyses of PNVC‐FO resin and PNVC‐FO‐AB composite revealed formation of spherical particles and aggregates of irregular shapes respectively. Thermogravimetric analyses revealed the overall stability order as: AB > PNVC‐FO‐AB composite > PNVC‐FO resin > PNVC homopolymer. In sharp contrast to PNVC and PNVC‐FO resin, which were both nonconducting (10^?12 to 10^?16 S/cm), the conductivity of the composites reached values between 0.75 S/cm and 6.54 S/cm corresponding to AB loading of 28–49 wt % respectively. Temperature versus conductivity studies revealed an initial increase in conductivity upto 200°C and current–voltage characteristics of the PNVC‐FO‐AB composite showed a linear trend consistent with Ohmic behavior. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 3837–3843, 2007     

Preparation and evaluation of composites from montmorillonite and some heterocyclic polymers. II. A nanocomposite from N‐vinylcarbazole and ferric chloride‐impregnated montmorillonite polymerization system

The polymerization of N‐vinylcarbazole in the presence of FeCl₃‐impregnated montmorillonite resulted in the formation of a poly(N‐vinylcarbazole)–montmorillonite composite. XRD analysis of the composite revealed no expansion for d₀₀₁ spacing, in sharp contrast to that for the same composite prepared in the absence of FeCl₃. This indicated that the poly(N‐vinylcarbazole) was not intercalated in the montmorillonite lamellae but was glued to it in the same way as was polypyrrole in colloidal silica, zirconia, or tin oxide nanocomposite systems. TEM analysis revealed the particle size of the composite to be in the range 30–40 nm. The dc conductivity of the poly(N‐vinylcarbazole)–montmorillonite composite was in the range (3–5) × 10⁻⁵ S/cm depending upon the FeCl₃ loading of montmorillonite. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 2971–2976, 1999     

Poly(N‐vinylcarbazole)–clay nanocomposite materials prepared by photoinitiated polymerization with triarylsulfonium salt initiator

A series of polymer–clay nanocomposite (PCN) materials that consist of poly(N‐vinylcarbazole) (PNVC) and layered montmorillonite (MMT) clay are prepared by effectively dispersing the inorganic nanolayers of MMT in an organic PNVC matrix via in situ photoinitiated polymerization with triarylsulfonium salt as the initiator. Organic NVC monomers are first intercalated into the interlayer regions of the organophilic clay hosts, followed by one‐step UV‐radiation polymerization. The as‐synthesized PCN materials are typically characterized by Fourier transform IR spectroscopy, wide‐angle X‐ray diffraction, and transmission electron microscopy. The molecular weights of PNVCs extracted from the PCN materials and the bulk PNVC are determined by gel permeation chromatography analysis with tetrahydrofuran as the eluant. The morphological image of the synthesized materials is observed by an optical polarizing microscope. The effects of the material composition on the optical properties and thermal stability of PNVCs and a series of PCN materials (solution and fine powder) are also studied by UV–visible absorption spectra measurements, thermogravimetric analysis, and differential scanning calorimetry, respectively. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1904–1912, 2004     

A conducting nanocomposite of acetylene black with preformed poly‐N‐vinylcarbazole crosslinked by anhydrous FeCl3

A conducting nanocomposite of crosslinked poly‐N‐vinylcarbazole (CLPNVC) with nanodimensional acetylene black (AB) was prepared by oxidative crosslinking of preformed PNVC through pendant carbazole moieties in presence of anhydrous FeCl₃ as an oxidant and AB suspension in CHCl₃ medium at 65°C. The incorporation of CLPNVC moieties in the CLPNVC‐AB composite was endorsed by Fourier transform infrared analysis. Scanning electron microscopic analysis showed formation of lumpy aggregates with average sizes in the 130–330 nm ranges. The thermal stability of the CLPNVC‐AB composite was appreciably higher than that of the PNVC‐AB composite. The direct current conductivities of the composites were significantly enhanced relative to that of the PNVC homopolymer (10^?12–10^?16 S/cm) and varied in the range of 10^?4–10^?2 S/cm depending on the amount of AB loading in the CLPNVC‐AB composite. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 819–824, 2006     

Photoemission and conductivity measurement of poly(N‐methyl aniline) and poly(N‐ethyl aniline) films

The studies involve the X‐ray photoelectron spectroscopy (XPS) and conductivity measurements of poly(N‐methyl aniline) and poly(N‐ethyl aniline) films deposited electrochemically at different pH values of −0.96, 2.22, and 3.78 for N‐methyl aniline and 1.10, 2.22, and 3.78 for N‐ethyl aniline. The results obtained reveal significant differences in the film properties of the two matrices as a function of pH of solution. These differences are explained on the basis of the competitive reaction products formed during polymerization in the two matrices along with the differences in the electron‐donating ability of the methyl and ethyl groups present on the nitrogen (N) atom. These results are further supported by the UV–Visible and IR data. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 1286–1292, 1999     

Structure and thermal degradation of poly(N‐phenyl acrylamide) and poly(N‐phenyl methacrylamide)

Poly(N‐phenyl acrylamide) (PPA) and poly(N‐phenyl methacrylamide) (PPMA) were prepared by using N‐phenyl acrylamide and N‐phenyl methacrylamide as monomer, respectively, in tetrahydrofuran using azobisisobutyronitrile as initiator. FT‐IR, ¹H‐NMR, and GPC were used to characterize their molecular structure. The PPA obtained exhibited higher molecular weight and wider molecular weight distribution than that of PPMA. Their thermal degradation and kinetics were systematically investigated in two atmospheres of nitrogen and air from room temperature to 800°C by thermogravimetric analysis at 10°C/min. Based on the thermal decomposition reactions in nitrogen and air, it is shown that a three‐step degradation process in nitrogen and a four‐step degradation process for two polymers were observed in this investigation. The initial thermal degradation temperature was lower than 190°C. Under two atmospheres, PPA exhibits higher degradation temperature, higher temperature at the maximum weight‐loss rate, faster maximum weight‐loss rates, and larger weight loss for the first‐stage decomposition, as well as higher char yield at 500°C than those of PPMA. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1065–1071, 2003     

Synthesis of Co3O4/Poly(N‐vinylcarbazole) Core/Shell Composite With Enhanced Optical Property

Co₃O₄/poly(N‐vinylcarbazole) (PNVC) composite with enhanced optical property was synthesized via a simple in situ bulk polymerization of NVC monomers in the presence of Co₃O₄ nanoparticles at an elevated temperature. High‐resolution electron microscopic observations showed that the Co₃O₄ nanoparticles were coated with uniform nanolayer shells of PNVC. Fourier‐transform infrared (FT‐IR) spectroscopy revealed the presence of strong interactions between the PNVC polymer chains with the Co₃O₄ surface in the Co₃O₄/PNVC composite. Raman spectroscopic results supported conclusions based on electron microscopy and FT‐IR spectra. The uniform nanolayer coating of PNVC decreases the inherent bulk conductivity of Co₃O₄, however, significantly increases the fluorescence property of Co₃O₄ nanoparticles.

     

Polymerization of N‐vinylcarbazole by multiwalled carbon nanotube

N‐vinylcarbazole (NVC) was polymerized in bulk or in toluene in presence of multiwalled carbon nanotube (MWCNT) without any extraneous catalyst. The formation of polyN‐vinylcarbazole (PNVC) was endorsed by striking agreement of FTIR, fluorescence and UV‐visible spectroscopic, thermogravimetric stability, differential scanning calorimetry, and dielectric characteristics of this polymer with the corresponding literature data for authentic PNVC samples prepared by free radical or carbocationic initiation. The polymerization was supposed to be initiated by a single electron transfer between N lone pair of NVC and the electron deficient MWCNT moieties. While PNVC homopolymer is nonconducting (10^?12 to 10^?16 S/cm), a composite of PNVC with MWCNT isolated from the polymerization system showed high dc conductivity varying from 1.3 to 33 S/cm depending upon the extent of MWCNT loading in the composite. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 4121–4126, 2007     

Conducting composites prepared by the reduction of silver ions with poly(p‐phenylenediamine)

Poly(p‐phenylenediamine) (PPDA) and also its ladder‐like analogue were prepared by oxidation of p‐phenylenediamine with ammonium peroxydisulfate in an aqueous solution of 0.4 mol L^?1 hydrochloric acid and converted to PPDA bases. These were used as reductants of silver nitrate to silver nanoparticles in 1 mol L^?1 methanesulfonic acid or in water at various mole ratios of silver nitrate to p‐phenylenediamine units from 0 to 1.8. The original conductivity of the PPDA, 10^?12 S cm^?1, increased to the order of 100 S cm^?1 for the PPDA–silver composites containing 27–40 wt% (i.e. 4.5–6.6 vol%) silver. Fourier transform infrared spectra indicated a practically unchanged molecular structure of PPDA in the composites. In contrast, Raman spectroscopy showed the existence of regions with unchanged molecular structure of PPDA as well as the presence of regions containing silver particles and oxidized PPDA moieties. © 2014 Society of Chemical Industry     

Tunable size and shape of conductive poly(N‐methylaniline) based on surfactant template and doping

Poly(N‐methylaniline) (PNMA) is one of the polyaniline derivatives with N‐substituted position. Polyaniline derivatives have attracted attention due to their higher solubility in common solvents than pristine polyaniline, but they still possess lower electrical conductivity. In this work, PNMA was synthesized via chemical oxidative polymerization in an ethanol–water system. The effect of surfactant type, namely anionic sodium dodecylbenzenesulfonate (SDBS), cationic cetyltrimethylammonium bromide and non‐ionic Tween20, on the electrical conductivity, doping level and morphology was investigated. PNMA prepared with the SDBS system possessed the highest electrical conductivity among the obtained PNMAs with and without surfactants. The effect of $N_{{\mathrm{\text{HClO}}}_4}$/N_NMA dopant mole ratios on the re‐doping, crystallinity, morphology and particle size was also examined. Using an $N_{{\mathrm{\text{HClO}}}_4}$/N_NMA mole ratio of 10:1 in the re‐doping process provided the highest electrical conductivity of 15.53 ± 2.5 S cm^?1, a doping level of 55.59%, along with hollow spherical particles with the thinnest membrane. Electron microscopy images revealed that the morphology of PNMA particles depended mainly on the surfactant type but not the $N_{{\mathrm{\text{HClO}}}_4}$/N_NMA mole ratio. © 2019 Society of Chemical Industry     

Synthesis and thermal studies of poly(N‐acryloyl,N′‐cyanoacetohydrazide) complexes with Co(II), Fe(III), and UO2(II) ions

Polymer complexes with uranium, cobalt, and iron chlorides were synthesized and investigated by elemental analysis, electronic (uv–visible), IR vibration, and magnetic moment measurements. The thermal stabilities of N‐acryloyl,N′‐cyanoacetohydrazide (ACAH) homopolymers and polymer complexes of poly(ACAH) (PACAH) with metal chlorides were studied thermogravimetrically. The rates of polymerization of PACAH in the absence and presence of metal chlorides were studied. The activation energies of the degradation of the homopolymer and polymer complexes were calculated using the Arrhenius equation. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3354–3358, 2003     

ABTS•+ scavenging activity of polypyrrole,polyaniline and poly(3,4‐ethylenedioxythiophene)

Although many methods are available for the evaluation of the antioxidant capacity of samples presented in the liquid state, typically food and beverages, to date only the 2,2′‐diphenyl‐1‐picrylhydrazyl (DPPH) assay has been applied to the measurement of the antioxidant capacity of solid samples such as active packaging materials. A modified 2,2′‐azino‐bis(3‐ethylbenzothiazoline‐6‐sulfonic acid) diammonium salt (ABTS) assay has been successfully developed for the measurement of the antioxidant capacity of conducting polymer powders. The ABTS^?+ radical scavenging activity of polypyrrole (PPy), polyaniline (PANI) and poly(3,4‐ethylenedioxythiophene) (PEDOT) powders was compared. The ranking order for greatest antioxidant capacity among the conducing polymer powders was PANI > PPy > PEDOT. The reduced forms of all the three conducting polymer samples were found to show greater radical scavenging activity than their as‐prepared partially oxidized forms. The modified ABTS assay is a simple, rapid and sensitive method for evaluating the antioxidant capacity of conducting polymer powders. The method is also suitable for composite antioxidant materials comprising a conducting polymer and a conventional packaging polymer. Copyright © 2010 Society of Chemical Industry     

Effect of poly(n‐isopropyl acrylamide‐co‐itaconic acid) on the chemical polymerization of pyrrole with (NH4)2[Ce(NO3)6]

The chemical oxidative polymerization of pyrrole (Py) by ceric ammonium nitrate (CAN) in the presence of polyitaconic acid and its copolymers (Polymer) containing 75 and 50 mole% N‐isopropylacrylamide were investigated. The effects of copolymer composition and addition order of the components on the reaction mechanism were studied by following the absorption spectra of the soluble reaction products between 200 and 1100 nm. As to the UV‐visible, FTIR and conductivity results of soluble products obtained from Polymer‐CAN‐Py system, it was assumed that the pyrrole polymerization by chemical oxidation was inhibited in the presence of the water‐soluble polyelectrolyte because an important part of ceric ammonium nitrate was consumed to produce radicals on the chains. On the other hand, the role of the copolymers in the case of Py‐CAN was mainly to prevent precipitation of polypyrrole. Consequently, the reaction prepared according to the first order of addition of the reactants favour the formation of oligomeric pyrrole, while the second order of addition yields solution of colloidal polypyrrole interacting with polyelectrolytes. © 1999 Society of Chemical Industry     

Properties of interpenetrating polymer network hydrogels composed of poly(vinyl alcohol) and poly(N‐isopropylacrylamide)

Interpenetrating polymer network (IPN) hydrogels based on poly(vinyl alcohol) and poly(N‐isopropylacrylamide) were prepared by the sequential‐IPN method. The IPN hydrogels were analyzed for sorption behavior of water at 35°C and at a relative humidity of 95% using a dynamic vapor sorption system, and water diffusion coefficients were calculated. Differential scanning calorimetry was used for the quantitative determination of the amounts of freezing and nonfreezing water. Free water contents in the IPN hydrogel of IPN1, IPN2, and IPN3 were 45.8, 37.9 and 33.1% in pure water, respectively. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2041–2045, 2003     

Binary blends based on poly(N‐isopropylacrylamide): Miscibility studies with PVA,PVP, and PAA

Blends of poly(vinyl alcohol) (PVA), poly(acrylic acid), (PAA), and poly(vinyl pyrrolidone) (PVP), with poly(N‐isopropylacrylamide) (PNIPAM), were prepared by casting from aqueous solutions. Mechanical properties of PNIPAM/PVA blends were analyzed by stress–strain tests. Differential scanning calorimetry (DSC) and scanning electron microscopy (SEM) were employed to analyze the miscibility between the polymeric pairs. The results revealed that PNIPAM is not miscible with PVA and PVP in the whole range of composition. On the other hand, PNIPAM interacts strongly with PAA forming interpolymer complex due to the formation of cooperative hydrogen bonds. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 743–748, 2004     

A study on solution properties of poly(N,N‐diethylacrylamide‐co‐acrylic acid)

Poly(N,N‐diethylacrylamide) (PDEA), poly(acrylic acid) (PAA), and a series of (N,N‐diethylacrylamide‐co‐acrylic acid) (DEA‐AA) random copolymers were synthesized by the method of radical polymerization. The measurement of turbidity showed that the phase behaviors of the brine solutions of the copolymers changed dramatically with the mole fraction of DEA (x) in these copolymers. Copolymers cop6 (x = 0.06) and cop11 (x = 0.11) in which acrylic acid content was higher presented the upper critical solution temperature (UCST) phase behaviors similar to PAA. Copolymer cop27 (x = 0.27) presented the lower critical solution temperature (LCST) behavior similar to PDEA. While copolymer cop18 (x = 0.18) in which acrylic acid content was moderate presented both UCST and LCST behaviors. The solution properties of the polymers were investigated by measurements of viscosity, fluorescence, and pH. It is reasonable to suggest that the sharp change of the phase behavior may be attributed to the interaction between acrylamide group and carboxylic group in the (DEA‐AA) copolymers. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Preparation and characterization of thermosensitive poly(N‐isopropylacrylamide)/poly(ethylene oxide) semi‐interpenetrating polymer networks

Temperature‐sensitive poly(N‐isopropylacrylamide) hydrogels were successfully synthesized by using poly(ethylene oxide) as the interpenetrating agent. The newly prepared semi‐interpenetrating polymer network (semi‐IPN) hydrogels exhibited much better properties as temperature‐sensitive polymers than they did in the past. Characterizations of the IPN hydrogels were investigated using a swelling experiment, FTIR spectroscopy, and differential scanning calorimetry (DSC). Semi‐IPN hydrogels exhibited a relatively high temperature dependent swelling ratio in the range of 23–28 at room temperature. DSC was used for the determination of the lower critical solution temperature of the semi‐IPN hydrogel. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3032–3036, 2003