ELECTRICALLY CONDUCTIVE COMPOSITE PREPARED BY ELECTROCHEMICAL POLYMERIZATION OF PYRROLE IN POLY-(p- PHENYLENE TEREPHTHALAMIDE) MATRIX

The preparation of PPy/PPTA conductive composite films by electrochemical method is presented.The first step is to cast a thin layer of poly (p-phenylene-terephthalamide) (PPTA) on a slice of Pt working electrode. The second step is to electrochemically polymerize pyrrole on the PPTA/Pt working electrode. Both of the electrical conductivity and the mechanical properties of the PPy/PPTA composite film are better than those of the pure PPy film, and the film has excellent flexibility at low temperature, even in liquid nitrogen.The SEM picture of the cross-section of PPy,/PPTA composite film showed that the two components were well mixed.Cyclic voltammograms of PPy,/PPTA film in aqueous solution showed that the conductive films could be reduced and reoxidized.     

二氧化硅改性片状铁粒子的微波吸收性能

The preparation and microwave-absorbing behavior of micrometric silica-modified platelet iron particles (SMPLIP) were investigated. Through precipitation， hydrothermal reaction， silica-modification and reduction with hydrogen， micrometric porous SMPLIP were yielded. The permittivity values of SMPLIP had been significantly decreased due to the presence of silica. Measurements and calculations showed that a 1.93mm thick sample containing SMPLIP as much as 60% by weight was capable of absorbing X band(8.2～12.4GHz) microwaves with reflection loss being greater than -10dB within the frequency range of 8.2～11.36GHz， while the maximum re-flection loss was -14.8dB at 9.4GHz. The results had also shown that it was practicable to prepare thin， light-weight microwave absorbent with SMPLIP.     

Synthesis and Structure of PEDOT Prepared through a Modified LB Film Method

Adopting LB film method, an arachidic acid (AA)/PEDOT multilayer LB film and polymerized EDOT monomers in hydrophilic group of LB were chosen to prepare the arachidic acid (AA)/PEDOT multilayer LB film. UV-Vis, FT-IR and XPS analyses implied that EDOT was effectively polymerized in film, and thus PEDOT conducting polymer was produced. Analyses of XRR and SIMS indicated that the film had a well-arranged lamella structure, and further research showed that polymerization of EDOT in AA film destroyed the orderliness of the original LB film. This phenomenon could be related to the destructive effect of polymerization on the layered structure. We used four-point probe and semiconductor instrument to study the conductivity property of the film, and observed that the conductivity of AA/PEDOT film had sudden changes with the changes of processing time in an effective conduction network, which was caused by "permeability" in conducting channel of multilayer film. The test results also indicated that the conductivity of AA/PEDOT film was obviously better than that of spin-coating PEDOT/PSS or ODA-SA/PEDOT-PSS film due to the higher π structure of PEDOT structure and ordered film structure.     

Synthesis and properties of organo-fly ash/polyaniline with core/shell structure based on emulsion polymerization

Organo-fly ash(OFA) was prepared with pretreated fly ash(FA) and hexadecyltrimethyl ammonium bromide (HDTMAB),and the composites composed of OFA and polyaniline were obtained by emulsion polymerization at different OFA weight ratios(2.0 wt%,5.0 wt%,10.0 wt%,15.0 wt%and 20.0 wt%) in the presence of dodecylbenzenesulfonic acid as dopant and emulsifier.A polymerization procedure was supposed.The electrical conductivities of the composites were tested by the four-probe technique.The chemical structure and crystallinity of the composites were confirmed by FT-IR and X-ray diffraction,respectively.Morphologies of FA,OFA and the composites were observed by SEM.The element analysis was performed by energy dispersive spectrometry.The thermal stability of the composites was analyzed by TGA.The results showed that the electrical conductivity of the composites decreased with increasing the feed weight ratio of OFA,and the lowest value was 0.62 S/cm.HDTMAB and PAn were just adsorbed on the surface of FA and OFA,respectively according to the physical adsorption without destroying the crystalline structure of FA or OFA.The surface became smoother after organification of FA by using HDTMAB,and its content on FA surfaces was about 26.9 wt%.The core/shell structure of the composite was observed by SEM analysis.The composites showed a higher thermal stability than pure PAn by introduction of OFA into this polymerization system,the heat stability of PAn was increased by decreasing 31.8 wt%of weight loss after introducing 20 wt%of OFA.     

Preparation and Characterization of Titania-grafted Poly（styrene-divinybenzene） Nanocomposite Microspheres

Titania-grafted poly（styrene-divinylbenzene）（TiO2/PSt-DVB） nanocomposite microspheres were prepared by an open-ring reaction and radical grafting copolymerization method. The TiO2 nanoparticles were first modified by attachment of epoxy groups to their surfaces to provide reactive groups that could covalently bond to the polymer （PSt-DVB） microspheres. The nanocomposite obtained was characterized by FTIR, SEM, XRD, and TGA analyses as well as UV-Vis spectrophotometry. The results indicated that the TiO2 nanoparticles were uniformly grafted onto the surface of the polymer microsphere producing grain sizes of about 5―10 μm. The modified TiO2 showed better UV absorbing property than the unmodified form, and the nanocomposite also retained the same UV absorbing property as the free modified TiO2 nanoparticle.     

Comparison of the Sol-gel Method with the Coprecipitation Technique for Preparation of Hexagonal Barium Ferrite

Hexagonal barium ferrite BaFe12O19 particles were prepared by sol-gel and coprecipitation methods, respectively. The composition of the so-obtained materials was investigated by means of XRD. By the sol-gel method, non-anticipated intermediate crystalline phases, such as γ-Fe2O3, α-Fe2O3, BaCO3, and BaFe2O4 etc., were formed with the delay of the formation of BaFe12O19. The formation of single phase BaFe12O19 required calcination at 850 oC for 4 h. On the other hand, using coprecipitation technique, amorphous hydroxide precursor was directly transferred into BaFe12O19 almost without the formation of intermediate crystalline phases. BaFe12O19 was prepared by calcining at 700 oC for 3 h. The results were confirmed by ESEM and VSM analyses. Based on the already reported results and the observed results in this study, it can be concluded that the coprecipitaion technique is easier to control than the sol-gel method for preparation of BaFe12O19 at a low temperature.     

Fabrication, Characterization, and Surface-Enhanced Raman Activity Study of Silver Coated Gold Nanoparticulate Films

This paper reports a study on the preparation of Ag-clad Au colloidal monolayer films by a combination of colloid self-assembly and liquid phase microwave high-pressure technique. Firstly, monodisperse Au nanoparticles prepared by microwave heating method were assembled onto a quartz slide. Then, these Au colloidal particles on the quartz surface acted as seeds for growing the Ag-clad Au composite particulate films. The obtained particulate films were characterized by UV-Vis spectra and atomic force microscopy. It was found that the thickness of the shell and thus the size of particles in the composite colloidal films could be controlled by deposition of Ag on the preformed Au colloidal particle film in the microwave reaction system, and such films significantly increased the surface-enhanced Raman scattering enhancement （SERS） ability compared with Au colloidal particle films. Their strong enhancement ability may mainly stem from relatively large particle consisting of Ag cladding as well as effective coupling among particles in the Ag-clad Au particle ftlms.     

Optical and mechanical properties of polyurethane/surface-modified nanocrystalline cellulose composites

in order to improve the optical and mechanical performances of waterborne polyurethane （WPU）, nanocrystalline cellulose （NCC）/WPU composites were synthesized in this study. NCC （prepared by acid hydrolysis of cotton fiber） was modified by （3-aminopropyl）triethoxysilane （APTES） to enhance its compatibility with WPU, and the surface-modified NCC was characterized by grafting ratio, crystallinity and contact angle （CA）. NCC/WPU composites were examined by scanning electron microscopy （SEM）, X-ray powder diffraction （XRD） and thermogravimetric analysis （TG）. The anti-yellowing property, specular gloss, pencil hardness, and abrasion resistance of NCC/WPU composites were investigated by the methods of Chinese National Standards GB/T 23999-2009, GB/T 9754-2007, GB/T 6739-2006 and GB/T 1768-2006, respectively. The results showed that the grafting ratio of NCC modified by 6% APTES was 36.01% and the crystallinity of modified NCC was decreased with the enhancement of APTES. CA of the modified NCC was decreased by 28.8% and the nanoparticles were homogeneously dispersed in the WPU matrix. The XRD patterns of the NCC/WPU composites were relatively steady, while the thermal stability of the composites was enhanced by 6.7% with 1.0 wt% modified NCC. Modified NCC affected the specular gloss of NCC/WPU composites more obviously than the anti-yellowing property. The pencil hardness of NCC/WPU composites was increased from 2H to 4H by addition of NCC and the abrasion resistance of the composites was enhanced significantly. In general, NCC/WPU composites showed significant improvements in the optical and mechanical performances.     

Kinetics study on the dissolution of UO_2 particles by microwave and conventional heating in 4 mol/L nitric acid

The dissolution of UO2 particles in 4 mol·L-1 nitric acid medium at temperatures of 90-110℃ by mi- crowave heating and conventional heating has been investigated, respectively. It is found that the dissolution ratios of UO2 particles by microwave heating were 10%-40% higher than that by conven- tional heating. Kinetics research shows that the dissolution of UO2 particles in 4 mol·L-1 nitric acid is controlled by the diffusion control model for microwave heating and by the surface reaction control model for conventional heating. The diffusion control model for the dissolution of UO2 particles by mi- crowave heating could be explained by the diffuseness on the surface of UO2 particles.     

STUDY ON THE SURFACE MODIFICATION OF NANO-TiO2 BY GRAFTING PMMA／PBMA AND ITS THERMAL STABILITY

The surface of nano-TiO2 was encapsulated with hydroxyl-propyl-methyl cellulose (HPMC), and then cografted with acrylates. Conditions of absorbing and grafting have been studied. Modified nano-TiO2 particles were characterized by FT-IR spectra, TEM and TG analysis. It was convinced from FT-IR studies that both methyl methacrylate (MMA) and butylmethacrylate (BMA) were co-grafted onto the surface of nano-TiO2 particles. TEM images show that the surface of nano-TiO2 particles was successfully modified by a thick layer of film-like polymer. TG results demonstrate that the decomposition temperature of HPMC-g-PMMA/PBMA, which has been grafted onto the surface of nano-TiO2, is 56.9 K higher than that of HPMC-g-PMMA/PBMA.     

Composite Electrodeposited PbO_2/Co_3O_4 on a Ti Substrate as Positive Electrode Materials for a Hybrid Supercapacitor

PbO_2/Co_3O_4 composites were prepared on a Ti substrate by means of a composite electrodeposition method in Pb~(2+) plating solution containing dissolved nano-Co_3O_4 particles. X-ray diffraction(XRD), scanning electron microscopy(SEM), energy dispersive spectrometry(EDS) and transmission electron microscopy(TEM) were used to characterize the chemical composition and morphology of the PbO_2/Co_3O_4 composites. The electrochemical and capacitance performance of the composites were investigated by cyclic voltammetry(CV), charge-discharge tests and electrochemical impedance(EIS). The results indicate that the composites comprise rutile phase Co_3O_4 and β-PbO_2. In addition, the surface of the composite electrode is rough and porous. The PbO_2/Co_3O_4 composites exhibit a high specific capacitance up to 215 F/g, which is ten times higher than that of the pure-PbO_2 and two times higher than that of the pure-Co_3O_4 in 1 mol/L NaOH electrolytes.     

TiO2/polyaniline composites： An efficient photocatalyst for the degradation of methylene blue under natural light

Polyaniline (PAn) sensitized nanocrystalline TiO_2 composites (TiO_2/PAn) were successfully prepared and used as an efficient photocatalyst for the degradation of dye methylene blue (MB).The results showed that PAn was able to sensitize TiO_2 efficiently and the composite photocatalyst could be activated by absorbing both the ultraviolet and visible light (λ:190～800nm),whereas pure TiO_2 absorbed ultraviolet light only (λ<380nm).Under the irradiation of natural light,MB could be degraded more efficiently on the TiO_2/PAn composites than on the TiO_2.Furthermore,it could be easily separated from the solution by simple sedimentation.     

Study on the Structure and Properties of Ordered Conductive Polymer Ultrathin Film

A Langmuir-Blodgett (LB) inducing method was firstly used to prepare single layer and multilayer conducting composite PEDOT-PSS film. The film-forming ability of ionization ODA and ODA-SA monolayer spread on PEDOT-PSS nanoparticle sub-phase and the behavior of ODA/PEDOT-PSS assembly particles on pure water were firstly investigated. The results indicated that nanoparticles in the suphase are packed in the ionization monolayer and stable complex Langmuir film is formed at the air/water interface. It has been found that the best film-forming conditions for composite film are as follows:distinct interface was formed between ODA and PEDOT-PSS layer and single layer thickness of PEDOT-PSS was about 23 nm,well accordant to the size of PEDOT-PSS nanoparticles. Different structures were designed to test the conductive ability of these composite films and a variable range hopping (VRH) model was used to explain the film conductive mechanism. The results indicated that a 3D-VRH model explained well the transferring of charge carrier in the multilayer film.     

Characterization and photocatalytic properties of silver and silver chloride doped TiO2 hollow nanoparticles

Using polystyrene（PSt） particles as template,PSt/TiO₂ composite particles with AgCl incorporation were prepared through hydrolysis of tetrabutyl titanate in the presence of AgNO₃ and NaCl.AgCl doped TiO₂ hollow particles were successfully prepared with the PSt/TiO₂ composite microspheres pretreated at 180℃followed by calcination.The morphology of PSt/TiO₂ particles and the crystal structures of the AgCl doped TiO₂ hollow particles were characterized.The photocatalytic activity of the doped TiO₂ hollow particles in degradation of Rhodamine B was tested under UV and visible lights and compared to that with Ag doped TiO₂ particles.The results showed that TiO₂ hollow particles,either doped with Ag or AgCl,demonstrated higher photocatalytic activity than the pure TiO₂ particles.This enhancement in photocatalytic activity was more significant with AgCl doped TiO₂ than that with Ag doped,and more distinct when the degradation was done under visible light than that under LTV light.     

Fabrication and characterization of Ba Ce0.8Y0.2O2.9-Ce0.85Sm0.15O1.925 composite electrolytes for IT-SOFCs

The Ba Ce0.8Y0.2O2.9-Ce0.85Sm0.15O1.925 composite electrolytes were prepared with Ba Ce0.8Y0.2O2.9(BCY) and Ce0.85Sm0.15O1.925(SDC). The SDC and BCY powders were mixed in the weight ratio of 95:5, 85:15, and 75:25, respectively(named as BS95, BS85, and BS75). Because of the composite effect between the SDC and BCY phases, the BS95 and BS85 exhibit improved conductivity compared with the pure SDC and BCY. The conductivity of BS95 is higher than that of BS85, indicating that the composite effect of BS95 is greater than that of BS85. Nevertheless, the composite effect in BS75 does not exist. Hence, we conclude that the composite effect in the BCY-SDC composites will decrease with the increase of the amount of BCY and even disappear when the amount of BCY exceeds a certain value. In our case, the optimum composition of the composite electrolyte is 95 wt% SDC and 5 wt% BCY. The BS95 has the highest conductivity(σ1t=0.07808 S cm-1, at 800 °C) and the fuel cell based on the BS95 shows the best performance(the maximum power density reaches as high as 526 mw cm-2 at 750 °C). The encouraging results suggest that the BCY-SDC composites are the very promising electrolyte materials for IT-SOFCs.     

Effect of nano-fillers on conductivity of polyethylene/low melting point metal alloy composites

A novel method for preparing conductive polyethylene(PE) composites has been developed. In the method, the powder of low melting point metal alloy(LMPA) is filled into the PE matrix by using twin screw extruder at a temperature below the melting point of the LMPA, and followed by a die drawing process at a temperature around the melting point of the metal alloy. It has been found that die drawing process, repeating the die drawing process and adding nano-fillers, such as montmorillonite(MMT) and multi-wall carbon nanotubes(MWCNTs), all help reduce the metal particle size in the PE matrix, thus improve the conductivity of the composite. The conductivity improvement is attributed to an increased number of the smaller metal particles. Therefore, conductive composites of polymer/metal alloy/nano-filler with high conductivity are possible to be prepared by using the new method.     

Preparation and Performance of HGM/PPENK-based High Temperature-resistant Thermal Insulating Coatings

Novel high temperature-resistant coatings with high mechanical strength and thermal-insulating performance were prepared with poly(ether nitrile ketone)(PPENK) resin as matrix and hollow glass microspheres(HGMs) as thermal-insulating filler. The corresponding mechanical and thermal-insulating study indicated that the mechanical properties of the coatings decreased with the increase of HGM content,and were improved after surface modification of HGM by KH570 resulting in enhancement of interaction between HGM and PPENK resin. The thermal conductivity of HGM/PPENK thermal-insulating coating decreased with the increase of HGM content and coating thickness, along with the decrease of the true density. It also showed slight increase trend due to HGMs surface modification. The HGM/PPENK coating filled with modified HGMs showed better thermal resistance than that of unmodified HGM/PPENK coating. The thermal decomposition temperature at 5%weight loss of the coating containing modified HGMs was 10 °C lower than that of pure PPENK, and 40 °C higher than that of neat HGM/PPENK coating. The coating exhibited commendable appearance after 400 °C for 30 min. The merits of HGM/PPENK-based thermal coatings obviously demonstrated promising prospect in thermal protection fields.     

Electrochemical characteristics of poly(ophenylendiamine) film electrodes in phosphatic solution

The electrochemical characteristics of poly(o-phenylendiamine) (POPD) film modified electrodes have been investigated using different electrochemical techniques.The main interest is focused on the effect of potential and film thickness on the electrode process.Good agreement has been found for the apparent diffusion coefficient estimated by chronocoulometry and impedance spec-troscopy.The charge transfer process within POPD films is diffusion processes at negative and positive overpotentials and electron hopping mechanism at formal potential.The POPD film conductivity of the oxidized state is better than that of the reduced state.For all electrode processes,the H+ may penetrate the film/electrolyte interface and take part in charge transfer or protonation-deprotonation of phenazine rings.     

Effects of Ag Doping Content and Dispersion on the Photocatalytic and Antibacterial Properties in ZnO Nanoparticles

ZnO nanoparticles(NPs)with different contents of Ag dopants were obtained by one-step solvothermal method.The crystalline structures of the prepared composites were characterized by means of X-ray diffraction(XRD).The morphology and composition of the samples were studied by means of scanning transmission electron microscopy(TEM)5 X-ray photoelectron spectroscopy(XPS)and electron microscopy(SEM).Photoluminescence(PL)spectra have been used to investigate pure ZnO,Ag-ZnO and Ag-ZnO-PVP NPs to determine the effect of composition on PL properties.It was found that the Ag-ZnO samples showed stronger emissions than pure ZnO.The catalytic activity of samples was measured by the degradation rate of R6G,which exhibited that Ag-ZnO nanocomposite demonstrated enhanced photocatalytic activity compared to the pure ZnO NPs.The possible influence factors to the photocatalytic and antibacterial activities of the sample were explored,including Ag contents and dispersion.It was presented that the photocatalytic activity of Ag-ZnO-PVP was better than that of Ag-ZnO and it showed the highest photocatalytic activity with 7%of Ag content.The Ag-ZnO-PVP can kill the Escherichia coli(E.coli)cells.     

Effect of Monomer Feeding Mode on thePreparation of Hollow Latexes with High MAA Content in the Core Latex Preparation简

In order to prepare hollow latex particles with optimum morphology based on osmotic swelling principle, three- layer core/shell latex particles with 40 wt% MAA in the core were first prepared via multistep seeded emulsion copolymerization, in which monomers were added by a semi-continuous process with monomer addition under two different forms： pure monomers＇ mixture （monomer addition）, and pre-emulsified monomers （pre-emulsion addition）. Then, the hollow latex particles with different morphologies were obtained after alkali post-treatment. Influences of the monomer feeding mode on the emulsion polymerization and the particle morphology were investigated. Results showed that the pre- emulsion addition could significantly improve the polymerization stability in each step, and greatly enhance the uniformity of shell encapsulation. The sizes of the core and core/shell latex particles obtained by the pre-emulsion addition were smaller and more uniform than those synthesized by the monomer addition, and the hollow latex particles with intact morphology were generated by alkali post-treating of the core/shell latexes prepared from the pre-emulsion addition. As the core size increased, the morphology of the post-treated particles underwent evolution from hollow to collapse. Moreover, the mechanism of the particle morphological evolution was proposed.