Synthesis and Characterization of Polyindole/Poly(vinyl acetate) Conducting Composites

Composites of a polyindole (PIN) and poly(vinyl acetate) (PVAc) were prepared chemically using FeCl₃ as an oxidant agent in anhydrous media. The composite compositions were altered by varying the indole monomer during preparation. The composites were characterized by FTIR and UV‐visible spectroscopies, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), stress‐strain experiments and conductivity measurements. Moreover, the film of PVAc and PIN/PVAc composites were prepared by casting on glass Petri dishes to examine their stress‐strain properties. PIN/PVAc composites are thermally more stable than PIN. It was found that the conductivities of PIN/PVAc composites depend on the indole content in the composites.     

Synthesis and characterization of poly (indene‐co‐pyrrole) nanofibers

Nanofibers of poly (indene‐co‐pyrrole) (CInPy) have been synthesized, using a facile chemical oxidative polymerization reaction. The effect of copolymerization was examined in view of the individually synthesized homopolymer nanostructures of polyindene (PIn) and polypyrrole (PPy). Morphological details of CInPy, studied using scanning electron microscopy (SEM) and transmission electron microscopy, (TEM) reveal the appearance of dense cottony mess, comprising of fine fibers with an average diameter of 5–10 nm. Chemical structural analysis of CInPy, conducted using ultraviolet‐visible (UV‐Vis), Fourier transform infrared (FTIR), and nuclear magnetic resonance (NMR) spectroscopic techniques, reveals that both PIn and PPy are involved in the formation of copolymer organization. Fluorescence properties of nanosized copolymer are observed in the blue region, with emission λ_max placed at 395 nm. Conductivity of copolymer nanofibers (2.4 × 10^?3 S/cm) is consistent with the morphology and thermal stability properties of integral homo‐polymers. Improved thermal stability and processability along with the enhanced optical and electrical properties of copolymer nanostructures outfit it as a better promising material in optoelectronic and light emitting nanodevices, with reference to nanosized PIn and PPy. Copyright © 2009 John Wiley & Sons, Ltd.     

Preparation of conducting poly(vinyl chloride)/polyindole composites and freestanding films via chemical polymerization

This study covers the synthesis of conducting polyindole (PIN) homopolymer, poly(vinyl chloride)/polyindole (PVC/PIN) composites, and preparation of their freestanding films. PIN and composites were synthesized chemically by radicalic mechanism using FeCl₃ as an initiator. Films of PVC and PVC/PIN composites were prepared by casting on glass Petri dishes. Mechanical properties of films were examined by stress–strain experiments. From FTIR spectra of polymers, it was revealed that polymerization reaction occurred by 2–3 mechanism. The conductivities of polymers at different temperatures were also measured by four‐probe technique and found in the range 10^?4 to 10^?5 S cm^?1. Magnetic properties of the polymers were analyzed by Gouy scale measurements and were found that their conducting mechanisms are of polaron and bipolaron natures. Thermal properties of polymers were investigated by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) and found that they had shown adequate thermal stability. X‐ray diffraction (XRD) spectra showed the amorphous nature of the polymers. Scanning electron microscopy (SEM) was used for microstructural analysis. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1290–1298, 2010     

Synthesis and Electrorheological Characterization of Polyaniline/Barium Titanate Hybrid Suspension

As organic/inorganic composites having attracted much attention due to their heterogeneous physical properties, conducting polyaniline (PANI) and barium titanate (BaTiO₃) which possesses large electronic resistance and excellent dielectric strength, were utilized to synthesize PANI/BaTiO₃ hybrid which is applicable for an electrorheological (ER) material via ‘in-situ’ oxidative polymerization. Physical properties of the obtained PANI/BaTiO₃ composites were characterized via Fourier-transform infrared spectra (FT-IR), thermogravimetry analysis (TGA), and scanning electron microscopy (SEM). The ER behaviors were investigated via a rotational rheometer, and their shear stresses were fitted using our previously proposed rheological equation of state.     

Effect of pretreatment on microstructure and photocatalytic activity of kaolinite/TiO<Subscript>2</Subscript> composite

Kaolinite/TiO₂ composites were prepared by using sol-gel method and raw kaolin, pretreated kaolinite and tetrabutyl titanate as the main raw materials. X-ray diffractometer, field-emission scanning electron microscope and infrared spectrometer analysis were carried out to characterize the phase composition and microstructure of the samples. The photocatalytic performance of the kaolinite/TiO₂ composites were evaluated by degrading the methylene blue (MB) and phenol aqueous solution, respectively. The results show that intercalation and exfoliation reduced the size and thickness of kaolinite particles. Acid treatment improved the distribution and the loading quantity of TiO₂ grains. When the kaolinite/TiO₂ composites were calcined at 500?°C, the tetragonal structure of anatase particles of 30–100?nm in size were obtained, but the exfoliated kaolinite crystals were damaged. The degradation rate of MB increased gradually with the extension of photocatalytic reaction time and the enhancement of photocatalyst dosage. The adsorption performance of acid-treated kaolinite/TiO₂ composite (AKT) was nearly the same as that of raw kaolin/TiO₂ composite (RKT), but that of the exfoliated kaolinite/TiO₂ composite (EKT) was the most excellent. The photocatalytic performance of AKT and EKT were better than that of RKT, and AKT exhibited the optimum property. Under a certain photocatalyst dosage and photocatalysis time, the absorption rate and the degradation rate decreased gradually with the enhancement of initial concentration of MB. Similar result was also acquired for the degradation of phenol. Both the acid treating and the exfoliating to kaolinite enhanced the photocatalytic performance of the kaolinite/TiO₂ composite photocatalysts, but acid treatment may be more helpful to the preparation of high performance kaolinite/TiO₂ composite photocatalyst.

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Characterization of kaolinite/emulsion-polymerization styrene butadiene rubber (ESBR) nanocomposite prepared by latex blending method: Dynamic mechanic properties and mechanism

The latex blending method was chosen to prepare Kaolinite/emulsion-polymerization styrene butadiene rubber (ESBR) nanocomposite to improve the interaction between filler particles and rubber matrix chains. The influences of kaolinite particles size, filler contents, and flocculants types on dynamic mechanical properties and the relative reinforcement mechanism of the prepared composite were systematic investigated and proposed. The transmission electron microscopy (TEM) and scanning electron microscopy (SEM) showed that the kaolinite particles were finely dispersed into the rubber matrix and arranged in parallel orientation. The prepared nanocomposites by latex blending exhibited improved crosslinking characteristic and dynamic mechanical parameters. The KAl (SO₄)₂ flocculant presented obvious modification in dynamic properties and crosslinking characteristic. Both the decrease in kaolinite particle size and the increase in kaolinite content can greatly improve the storage modulus and reinforcing effect of kaolinite/ESBR nanocomposites. The dynamic reinforcement mechanism of kaolinite can be explained by filler network including a certain thickness of rubber shell on the surface of kaolinite lamellar structure and the aggregations network between kaolinite particles The optimum way to balance the dynamic properties of rubber nanocomposites at different temperatures is to reduce the surface difference between kaolinite and rubber matrix and the degree of filler-filler networking on the basis of kaolinite with nanoscale (nanometer effect).     

Effect of Cement on Properties of Inverted Emulsions and Polymers from Vinyl Monomers with Acid Anhydride-Adducted Polypropylene Glycol

Abstract

Adduct polymer (PPGMA) prepared from polypropylene glycol and maleic anhydride was found to give stable inverted emulsions when mixtures of cement, water, and vinyl monomers were vigorously stirred in the presence of PPGMA. In this case, the carboxyl groups of PPGMA were neutralized with metal ions generated from the cement into neutralized PPGMA which acts as an effective W/O type emulsifier. The inverted emulsions containing cement gave a new type of polymer-cement composites by polymerization of the vinyl monomers and also by hardening of the cement. Water-free composites were easily obtained by removing evaporative water. The effect of cement on the physical properties of the water-free composites was remarkable. Further, the use of mixed fillers of cement and Al(OH)₃ was found to improve the flame-retardant properties of the composites; however, increasing the Al(OH)₃ content in the fillers resulted in a decrease in the physical properties. Generally, the composites have improved resistance to acid media in which the usual foamed hydrated cement is eroded.     

Leaching test for calcined kaolinite and kaolinite/TiO<Subscript>2</Subscript> photoactive composite

Kaolinite is a suitable material for fixing TiO₂ nanoparticles in a composite form. The kaolinite/TiO₂ composite has promising photoactive properties which are as important as is the possible impact of the composite on the environment. Accordingly, the stability of the kaolinite/TiO₂ composite dried at 105°C (KTI1) and calcined at 600 °C (KTI6) and the stability of the original kaolinite treated at various temperatures (105–800 °C) were studied by the leaching test in accordance with European standard BS EN 12457-2:2002 (British Standards Institution, 2002). The stability was evaluated on the basis of elements leached from the materials to extraction agents. Atomic emission spectrometry with inductively coupled plasma was used for determining the concentration of elements. In order to better understand the process of calcination and the structure changes in the kaolinite/TiO₂ composite and calcined kaolinite, the materials were evaluated using X-ray powder diffraction and infrared spectroscopy with Fourier transformation. The processes of kaolinite dehydroxylation and metakaolinite formation were observed. Kaolinite is an appropriate carrier for composite preparation due to its stability even after its treatment at high temperatures. The experiments confirmed the TiO₂ nanoparticles to be very strongly bound to the kaolinite surface. On the other hand, the experiments demonstrated that the presence of TiO₂ on the kaolinite surface caused the release of Al in high concentrations to the final extracts, especially after kaolinite/TiO₂ composite calcination.     

苯分子与Si6O18H12和Al6O24H30团簇模型相互作用的理论研究

粘土矿已经被广泛用来去除有机物,修复和净化被石油碳氢化合物污染的土壤和地下水. 我们选择高岭石作为研究对象,构造了Si₆O₁₈H₁₂和Al₆O₂₄H₃₀两个团簇模型分别代表高岭石的硅氧层表面和铝氧层表面,在MP2/6-31G(d,p)//B3LYP/6-31G(d,p)的理论水平上系统地研究了气态下苯分子和高岭石团簇模型的相互作用. 并进一步分析了苯分子和高岭石表面相互作用的各种气态性质,比如：优化的几何构型、结构参数、吸附能、自然键轨道电荷分布、振动频率变化、静电势、电子密度性质(次级氢键的电子密度和拉普拉斯算符值)和电子密度差分等. 优化的几何构型表明苯分子吸附在高岭石表面的本质可能是次级氢键的形成. 其他性质的结果进一步验证了次级氢键的存在,并指出苯更倾向于吸附在高岭石的铝氧层表面,且苯环和铝氧层表面形成近似90°的夹角.     

Effect of surfactant on electrokinetic properties of polyindole/TiO2-conducting nanocomposites in aqueous and nonaqueous media

In this study, polyindole (PIN)/TiO₂ nanocomposites were synthesized with and without the presence of sodium dodecylsulfate, anionic surfactant, with two different PIN contents. The synthesized materials were subjected to various characterizations namely: particle size, apparent density, conductivity, dielectric constants, magnetic susceptibility, elemental analysis, Fourier transform infrared spectroscopy spectroscopy, thermogravimetric analysis, X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. Characterization results revealed the successful preparations of PIN/TiO₂ hybrid nanocomposites. Electrokinetic properties of all the materials were determined by zeta (ζ)-potential measurements in aqueous and nonqueous media. Effects of pH, temperature, presence of various electrolytes, and surfactants on electrokinetic properties of the materials were examined.     

Plant extract-strategy using Teucrium Polium stems to green synthesize Ag/AgCl bionanocomposite imprinted on Fe3O4/kaolinite and potentials in catalytic and chemosensor applications

A two-component bionanocomposite was produced with an easy and green method and was expanded to the three and four-component nanostructures. In fact, the Ag/AgCl sample with the mean diameter of about 22 nm was biosynthesized using the aqueous extract of Teucrium Polium and then it was imprinted on kaolinite to produce the Ag/AgCl/kaolinite bionanocomposite with a particle size range of 5–35 nm. For the first time, the four-component Ag/AgCl/Fe₃O₄/kaolinite bionanocomposite, composed of the 19 nm nanorods of Fe₃O₄ in the vicinity of the 29 nm Ag/AgCl nanospheres was synthesized with the same method to promote the properties and applications. All the products could be utilized in the aqueous media, as both the useful biosensors to detect of Hg²⁺ with a minimum concentration of 100 μM and the efficient catalysts for the reduction of 4-nitrophenol to 4-aminophenol in 10–50 min. It’s remarkable that the as-prepared composites were characterized using the various techniques such as UV-Vis, FT-IR, XRD, FE-SEM, and EDX. Further, the vibrating sample magnetometry (VSM) measurement revealed the ferromagnetic nature of Ag/AgCl/Fe₃O₄/kaolinite. Therefore, the four-component nanocomposite has the ability to separate easily with the aid of an external magnet, in addition to its other valuable advantages like easy work-up, and high catalytic efficiency and sensor performance.     

Novel Magnetic Single-Walled Carbon Nanotubes/Methylene Blue Composite Amperometric Biosensor for DNA Determination

Abstract

A single-walled carbon nanotube (SWNT)/nano-Fe₃O₄/methylene blue (MB) magnetic composite was developed to fabricate the DNA biosensor. The magnetic SWNTs/nano-Fe₃O₄ and SWNTs/nano-Fe₃O₄/MB composites were prepared by chemical coprecipitation and adsorption, respectively. The morphology, infrared, and magnetic properties of different composites were characterized. The behavior of MB adsorbed in the composite matrix as indicator for the detection of DNA was studied via MB reductive current changes between after and before combination with DNA. Owing to the high electrical conduction of SWNTs and superparamagnetism of Fe₃O₄ nanoparticles, the biosensor exhibited simple operation, high sensitivity, and easy renewal. The biosensor was successfully applied to detect the hybridization of DNA.     

Synthesis and Characterization of Polyvinylferrocene/Polypyrrole Composites

Conducting polymer composites of polyvinylferrocene and polypyrrole (PVF/PPy) were synthesized chemically by the in situ polymerization of pyrrole in the presence of PVF using FeCl₃ as oxidant. Acetic (CH₃COOH) and boric (H₃BO₃) acids were used as the synthesis medium. Effects of the synthesis medium on the properties of the PVF/PPy composite were investigated. The PVF/PPy composites and homopolymers were characterized by fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and magnetic susceptibility techniques. Conductivity measurements were performed using the four‐probe technique. We found that the conductivities of PVF/PPy‐H₃BO₃ (1.19 S cm^?1) and PVF/PPy‐CH₃COOH (4.5×10^?1 S cm^?1) increased relative to those of the homopolymers of PPy‐H₃BO₃ (2.1×10^?2 S cm^?1) and PPy‐CH₃COOH (1.2×10^?2 S cm^?1) due to the interaction of PVF with the pyrrole moiety. The stability of all homopolymers and composites were investigated by thermogravimetric analysis and by conductivity measurements during heating‐cooling cycles. There was a small drop in conductivity caused by the annealing of PVF/PPy composites at 70°C. The conductivity of all samples increased with temperature and exhibited stable electrical behavior with increasing temperature. TGA analysis of samples showed that the composites were more stable than the homopolymers or PVF separately. The magnetic susceptibility values of samples were negative, except for PVF/PPy‐H₃BO₃. Morphology changes of the composites investigated by scanning electron microscopy (SEM), attributed to synthesis conditions, have a significant effect on their conductivity.     

In situ oxidative copolymerization and characterization of new poly(benzidine-<Emphasis Type="Italic">co</Emphasis>-<Emphasis Type="Italic">o</Emphasis>-phenylenediamine)/kaolinite microcomposites

Copolymers of benzidine and o-phenylenediamine/kaolinite clay composites with different percentages of kaolinite clay particles were synthesized via in situ oxidative copolymerization. The spectral characteristics upon incorporation of o-phenylenediamine units into the polybenzidine backbone in presence of kaolinite clay were investigated by means of UV–Vis and FTIR spectroscopy. The copolymer in the absence and in the presence of kaolinite clay was studied by thermal gravimetric analysis under non-oxidative conditions. The morphology of the copolymer kaolinite composites system was investigated by the scanning electron microscopy.     

Hydrophobic Silica Aerogels Strengthened with Nonwoven Fibers

Hydrophobic silica aerogels were prepared via a sol‐gel process by surface modification at ambient pressure. Nonwoven fibers were distributed inside the silica aerogels as a composite to act as a supporting skeleton which increased the mechanical property of the silica aerogels. The morphology and pore structure of the composites were characterized by scanning electron microscopy (SEM) and N₂ adsorption analyzer. The contact angle and the adsorption capacities of the composites were also determined. The results show that silica aerogels dispersed uniformly and maintained high porosity in the aerogel‐fiber composites. They have excellent hydrophobic properties and are excellent adsorptive materials.     

New polymeric based materials: terpoly(aniline,diphenyl amine,and o‐anthranilic acid) / kaolinite composites

Terpolymers of aniline, diphenyl amine and o‐anthranilic acid (PANIDPAA) / kaolinite clay composites were synthesized by 1:1:1 molar ratios of the respective monomers with different percentages of kaolinite clay particles via in situ chemical terpolymerization. The spectral characteristics upon incorporation of o‐anthranilic acid and diphenyl amine units into the polyaniline backbone in presence of kaolinite clay were investigated. The results were justified by measuring the UV–Vis absorption spectra, FT‐IR for PANIDPAA emeraldine base (EB), and PANIDPAA EB / kaolinite clay composite. Also, the thermal gravimetric analyses for the isolated terpolymer powder in the bulk in absence and in presence of kaolinite clay were carried out. Moreover, the morphology of the polymer clay composites system was studied by the scanning electron microscope micrographs at different magnifications. X‐ray diffraction was used to measure the nature of polymer and extent of crystallinity present in the neat terpolymer and terpolymer / kaolinite composite materials. Copyright © 2016 John Wiley & Sons, Ltd.     

Mechanical Properties of Copolymers from Methacrylate Functionalized Silanes and Bifunctional Methacrylate Monomers

Sol gel derived composite materials were prepared from methacryloxypropyltrimethoxysilane (MPTS) and tetraethyleneoxidedimethacrylate (TEGDMA). The amount of MPTS in the composites was varied from 0 to 50 mole%. MPTS was prehydrolyzed at room temperature with 0,1 mole/l HCl/H₂O. After complete removal of solvent calculated amounts of TEGDMA were added to the reaction mixture of the prehydrolyzed MPTS. Thermically initiated free radical copolymerization of the methacrylate endgroups was performed in the resulting mixture under nitrogen atmosphere using azobisisobutyronitril (AIBN) as initiator. The composites were investigated by high resolution transmission electronmicroscopy in order to investigate the morphology. The thermomechanical properties as storage, loss modulus, tan as well as the glass transition temperature (T _g ) of the composites were estimated by dynamic mechanical thermal analysis (DMTA).     

Synthesis of NaX and NaY Zeolites from Tunisian Kaolinite as Base Catalysts: An Investigation of Knoevenagel Condensation

The synthesis of Faujasite‐type zeolites with high purity has been successfully performed from Tunisian kaolinite and the effects of different crystallization parameters on the final products were widely investigated. The alkaline fusion of kaolinite followed by hydrothermal treatment lead to zeolite NaX synthesis whereas the classic hydrothermal transformation of metakaolinite produces NaY zeolite. The results show that an increase in the synthesis temperature and time has improved the crystallization process of the zeolite NaX whereas the SiO₂/Al₂O₃ and the Na₂O/SiO₂ molar ratios were the key parameters to obtain a pure zeolite NaY. The highest specific surface areas obtained with the optimal crystallization conditions were 554 m2 g^?1 and 592 m2 g^?1 for respectively NaX and NaY zeolites. The basic properties of NaX and NaY zeolites were explored in the Knoevenagel condensation of benzaldehyde with ethyl cyanoacetate at 140 °C as a test reaction in the absence of solvent. The influence of ion exchange with cesium cation on the catalytic activity of prepared catalysts was also investigated. It was found that the NaX provided higher activity than that of NaY catalyst due to its lower Si/Al ratio whereas a cesium exchange conferred higher basicity to the prepared Na‐faujasite.     

Comparison of the properties of waterborne polyurethane/multiwalled carbon nanotube and acid‐treated multiwalled carbon nanotube composites prepared by in situ polymerization

A series of waterborne polyurethane (WBPU)/multiwalled carbon nanotube (CNT) and WBPU/nitric acid treated multiwalled carbon nanotube (A‐CNT) composites were prepared by in situ polymerization in an aqueous medium. The optimum nitric acid treatment time was about 0.5 h. The effects of the CNT and A‐CNT contents on the dynamic mechanical thermal properties, mechanical properties, hardness, electrical conductivity, and antistatic properties of the two kinds of composites were compared. The tensile strength and modulus, the glass‐transition temperatures of the soft and hard segments (T_gs and T_gh, respectively), and ΔT_g (T_gh − T_gs) of WBPU for both composites increased with increasing CNT and A‐CNT contents. However, these properties of the WBPU/A‐CNT composites were higher than those of the WBPU/CNT composites with the same CNT content. The electrical conductivities of the WBPU/CNT1.5 and WBPU/A‐CNT1.5 composites containing 1.5 wt % CNTs (8.0 × 10⁻⁴ and 1.1 × 10⁻³ S/cm) were nearly 8 and 9 orders of magnitude higher than that of WBPU (2.5 × 10⁻¹² S/cm), respectively. The half‐life of the electrostatic charge (τ_1/2) values of the WBPU/CNT0.1 and WBPU/A‐CNT0.1 composites containing 0.1 wt % CNTs were below 10 s, and the composites had good antistatic properties. From these results, A‐CNT was found to be a better reinforcer than CNT. These results suggest that WBPU/A‐CNT composites prepared by in situ polymerization have high potential as new materials for waterborne coatings with good physical, antistatic, and conductive properties. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3973–3985, 2005     

Preparation and Properties of Conducting Polyolefins Composites

Abstract

The method of chemically initiated oxidative modification of polypropylene particles in suspension by pyrrole was used for preparation of conductive polypropylene/polypyrrole composites. Their properties were compared with another type of polypropylene/polypyrrole composites prepared by melt mixing of pure polypropylene with chemically synthesized polypyrrole and with polypropylene/carbon black composites also prepared by melt mixing.

The composites were characterized by elemental analysis and by rheological testing. The antistatic properties of prepared composites were demonstrated. The electrical and flow properties depend on the concentration of filler and on the processing conditions of composites.