Composites of polyaniline and lead dioxide: preparation,characterization, and catalytic activity

This paper is devoted to the preparation of polyaniline/lead dioxide composites (PANI/PbO₂) via chemical oxidation of aniline in H₂SO₄ medium using β-PbO₂ as an oxidant. The parameters affecting the polymerization reaction are considered. These parameters are [aniline], amount of β-PbO₂, stirring time, and different acids. The prepared composites were characterized by SEM, FT-IR, XRD, TGA, DTA, and elemental analysis. From XRD and FT-IR spectra, it was concluded that high molecular weight polymer could be obtained with high aniline concentration, high amount of β-PbO₂, increasing polymerization time and polymerization of ANI at lower temperatures. Thermogravimetric study exhibited that the composite prepared using high amount of β-PbO₂ has a higher thermal stability. The application of the composites in the oxidative degradation of Alizarin yellow G and Acid alizarin violet N dyes exhibited good catalytic activity in presence of H₂O₂ as an oxidant. The reactions followed first-order kinetics and the rate constants were determined.     

Synthesis, characterization and thermal analysis of polyaniline/ZrO2 composites

Conducting polyaniline-zirconium dioxide (PANI/ZrO₂) composites were synthesized by ‘in situ’ deposition technique in the presence of hydrochloric acid (HCl) as dopant by adding the fine grade powder (average particle size of approximately 20 nm) of ZrO₂ into the polymerization reaction mixture of aniline. The composites obtained were characterized by infrared spectra (IR) and X-ray diffraction (XRD) and thermogravimetric analysis (TGA). TG curves and DTG curves of the composites suggest that the thermal degradation process of PANI/ZrO₂ composites proceeds in two-steps and the composites are more thermally stable than that of the pure PANI. The improvement in the thermal stability for the composites is attributed to the interaction between PANI and ZrO₂, which restricts the thermal motion of PANI chains and shields the degradation of PANI in the composites.     

An elastomeric conducting composite based on polyaniline coated nylon fiber and chloroprene rubber

Chloroprene rubber-polyaniline (PANI) coated nylon fiber composites containing PANI powder were prepared by mechanical mixing on a two-roll mill. PANI was synthesized by chemical polymerization of aniline in presence of hydrochloric acid. PANI coated nylon fiber was prepared by in situ polymerization of aniline on nylon fiber. The cure parameters cure kinetics, filler dispersion, mechanical properties, DC electrical conductivity and thermal degradation parameters of the composites were evaluated. Cure rate index and cure reaction constants indicated that the rate of cure reaction changes on filler addition. Filler addition at higher loadings led to agglomeration. The tensile strength and modulus values increased suggesting a reinforcement effect. The conductivity, thermal characteristics and thermal degradation kinetic parameters are also presented.     

Thermal stability of several polyaniline/rare earth oxide composites (I): polyaniline/CeO<Subscript>2</Subscript> composites

Polyaniline (PANI)/CeO₂ composites were prepared by adding CeO₂ powder into the polymerization reaction mixture of aniline. Fourier transform infrared spectra (FTIR) and X-ray diffraction (XRD) were used to characterize the composites. Thermogravimetry (TG) and derivative thermogravimetry (DTG) were used to study the thermal stability of the composites. IR and XRD results show that interaction exists between PANI and CeO₂. This interaction maybe is hydrogen bonding action between the hydroxyl groups on the surface of the CeO₂ and the imine groups in the PANI molecular chains. TG–DTG analysis indicates that the thermal stability of the composites is higher than that of the pure PANI. The improvement in the thermal stability of the composites is attributed to the interaction between PANI and CeO₂, which restricts the thermal motion of PANI chains and shields the degradation of PANI in the composites.     

MnO_2/聚苯胺复合材料的电化学电容

以P123为模板剂,软模板法制备出纳米MnO2.酸性条件下引入苯胺并聚合,得到了MnO2/聚苯胺复合材料.X射线衍射(XRD)、红外光谱(IR),扫描电子显微镜(SEM)表征观察样品的结构、形貌.循环伏安、交流阻抗、恒电流充放电等测试MnO2/聚苯胺电极的电化学性能.结果表明:引入苯胺改变了样品纳米MnO2的形貌.MnO2/聚苯胺电极比容量高达190.8F·g-1,500次循环电极比容量仅衰减4.7%,库仑效率均保持在97%以上.     

Conductive Nanocomposites Based on Cellulose Nanofibrils Coated with Polyaniline-DBSA Via In Situ Polymerization

Summary: Cellulose nanofibrils (CNF) were extracted by acid hydrolysis from cotton microfibrils and nanocomposites with polyaniline doped with dodecyl benzenesulphonic acid (PANI-DBSA) were obtained by in situ polymerization of aniline onto CNF. The ratios between DBSA to aniline and aniline to oxidant were varied in situ and the nanocomposites characterized by four probe DC electrical conductivity, ultraviolet-visible-near infrared (UV-Vis - NIR) and Fourier-transform infrared (FTIR) spectroscopies and X-ray diffraction (XRD). FTIR and UV-Vis/NIR characterization confirmed the polymerization of PANI onto CNF surfaces. Electrical conductivity of about 10⁻¹ S/cm was achieved for the composites; conductivity was mostly independent of DBSA/aniline (between 2 and 4) and aniline/oxidant (between 1 and 5) molar ratios. X-ray patterns of the samples showed crystalline peaks characteristic of cellulose I for CNF samples, and a mixture of both characteristic peaks of PANI and CNF for the nanocomposites. Field emission scanning electron microscopy (FESEM) characterization corroborated the abovementioned results showing that PANI coated the surface of the nanofibrils.     

MnO2/PPy/PANI三元纳米管复合材料的合成及其电化学电容性能

在聚苯胺（PANI）和二氧化锰（MnO2）存在的条件下,以FeCl3/甲基橙为模板,通过化学氧化法聚合吡咯(Py)单体,制备MnO2/PPy/PANI纳米管复合材料。 利用X射线衍射、透射电子显微镜、红外光谱和电化学测试等多种测试技术对复合材料进行物性表征和电化学电容性能测试,并讨论了不同含量的PANI对复合物材料的结构和性能的影响。 结果表明,由于PANI、MnO2与PPy三者的相互协同作用,以及材料管状结构的大比表面积,使三元复合材料具有比二元复合材料要大的电化学活性。 所合成的三元复合材料最大比容量达到458.4 F/g。     

Micelle-assisted synthesis of polyaniline/magnetite nanorods by in situ self-assembly process

Polyaniline/magnetite nanocomposites consisting of polyaniline (PANI) nanorods surrounded by magnetite nanoparticles were prepared via an in situ self-assembly process in the presence of PANI nanorods. The synthesis is based on the well-known chemical oxidative polymerization of aniline in an acidic environment, with ammonium persulfate (APS) as the oxidant. An organic acid (dodecylbenzenesulfonic acid, DBSA) was used to replace the conventional strong acidic (1 M HCl) environment. Here, dodecylbenzenesulfonic acid is used not only as dopant, but also as surfactant in our reaction system. So, DBSA can excellently control the morphology and size of PANI nanorods and magnetite particles. Magnetite particles were formed simultaneously during sedimentation, and the formed nanorods were also decorated by the particles. The resulting PANI/magnetite composites were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). It is found that PANI/magnetite nanorod composites have uniform size, superparamagnetism and a small mass fraction of magnetite, thermal stabilization even at a higher temperature.     

Dendritic polyaniline nanoparticles synthesized by carboxymethyl chitin templating

Dendritic polyaniline (PANI) nanoparticles were synthesized via oxidative polymerization of aniline, using ammoniumperoxodisulfate as an oxidant, and CM-chitin as a template. The reaction was performed under acidic conditions and the template was removed after the polymerization was completed. Molecular characterization (including UV-vis, FTIR, TGA, and XRD) suggests that the structure of the synthesized dendritic PANI nanoparticles is identical to that of the emeraldine form of PANI, synthesized by the conventional route (without the addition of the CM-chitin template). SEM images reveal that the dendritic PANI nanoparticles have an average diameter in the nanometer range, and are globular in shape, with radially oriented PANI dendrites; in contrast, irregularly-shaped aggregates of PANI are obtained using the conventional synthesis. It was further found that the size of the dendritic PANI nanoparticles is dependent on the CM-chitin content. The higher the CM-chitin concentration, the smaller is the size of the dendritic PANI nanoparticles obtained. An interpretation of these observations and a possible formation mechanism are proposed based on self-assembly between the CM-chitin chains and the aniline monomer.     

模板合成H4PMo11VO40/聚苯胺纳米线列阵及其聚合机理探讨

在氧化铝模板中制备了HPA/PANI纳米线列阵,SEM、TEM表明列阵中纳米线直径约为80 nm;XRD与FT-IR证明形成了有效掺杂;单根纳米线的导电率为16.2 S.cm-1;材料的TG-DTA表明PANI纳米线材料有三步失重过程,失去吸附水过程,多酸失去结晶水和PANI结构持续分解过程,多酸结构分解过程;在氧化聚合过程中H4PMo11VO40即为质子酸又为氧化剂和掺杂剂;聚合反应采用自由基机理进行,掺杂反应发生在形成醌二亚胺式自由基正离子和双苯胺式自由基正离子和醌二亚胺式自由基正离子偶联聚合成链结构时.     

聚苯胺/离子液体/蒙脱土纳米复合材料的制备及其导电性能研究

采用1-羧甲基-3-甲基咪唑氯化盐离子液体对钠化蒙脱土进行插层改性,然后用苯胺的盐酸溶液进行二次插层,以过硫酸铵为氧化剂,盐酸溶液为掺杂剂,使进入离子液体/蒙脱土(CMMIm/MMT)层间的苯胺(An)发生氧化聚合反应,制备了一种具有良好导电性的聚苯胺/离子液体/蒙脱土复合材料(PANI/CMMIm/MMT).用红外光谱、X-射线衍射,热重分析和DSC对样品进行了表征.结果表明当离子液体/蒙脱土用量为7.5%、盐酸浓度为1mol/L、过硫酸铵与苯胺的摩尔比为1∶1、0℃下反应6h时制备的PANI/CMMIm/MMT纳米复合材料电导率最高,达到了0.3S/cm,是相同条件下聚苯胺/钠化蒙脱土纳米复合材料电导率的2.5倍,聚苯胺的7.5倍.     

Graphene oxide‐induced polymerization and crystallization to produce highly conductive polyaniline/graphene oxide composite

Graphene oxide (GO)–polyaniline (PANI) composite is synthesized by in situ polymerization of aniline in the presence of GO as oxidant, resulting in highly crystalline and conductive composite. Fourier transform infrared spectrum confirms aniline polymerization in the presence of GO without using conventional oxidants. Scanning electron microscopic images show the formation of PANI nanofibers attached to GO sheets. X‐ray diffraction (XRD) patterns indicate the presence of highly crystalline PANI. The sharp peaks in XRD pattern suggest GO sheets not only play an important role in the polymerization of aniline but also in inducing highly crystalline phase of PANI in the final composite. Electrical conductivity of doped GO–PANI composite is 582.73 S m^?1, compared with 20.3 S m^?1 for GO–PANI obtained by ammonium persulfate assisted polymerization. The higher conductivity appears to be the result of higher crystallinity and/or chemical grafting of PANI to GO, which creates common conjugated paths between GO and PANI. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 1545–1554     

Synthesis and characterization of red mud/polyaniline composites: Electrical properties and thermal stability

New types of conducting composites using red mud as an inorganic substrate and polyaniline as the conducting phase were prepared. Red mud/polyaniline (RM/PANI) composites were synthesized in acidic aqueous solution by the chemical oxidative polymerization of aniline using ammonium peroxydisulfate as the oxidant. The composites exhibit conductivities in the 0.42-5.2 S cm⁻¹ range, depending on the amount of polyaniline. They were characterized by infrared and UV-vis spectroscopy, scanning electron microscopy and X-ray diffraction. The IR and X-ray results show that PANI is deposited on the RM surface. The composites have a globular structure and the PANI globules synthesized on the surface of RM are smaller than those prepared under the same conditions without the substrate. Thermogravimetric analysis was used for investigation of the thermal stability of the composites. The thermal stability of the conductivity of RM/PANI composites was studied by ageing at 125 °C, the conductivity being measured in situ during this process.     

合成聚苯胺/碳化钨复合材料及聚合机理探讨

采用在原位聚合苯胺的反应介质中分散碳化钨(WC)的方法制备了掺杂聚苯胺/碳化钨(PANI/WC)复合物,并研究了苯胺在WC表面的聚合机理.通过扫描电镜(SEM)、透射电镜(TEM)、傅立叶红外光谱(FTIR)、拉曼光谱(Raman)和X射线衍射(XRD)对复合物进行了表征.结果表明,苯胺的聚合倾向于在WC颗粒表面进行,形成了PANI包覆WC的复合材料;WC粒子与PANI大分子之间存在强的相互作用,并且复合前后WC的晶型并未发生变化,WC的存在导致红外光谱有明显的蓝移现象,复合后在3446 cm-1处的红外吸收峰变得很弱;在拉曼光谱中,代表醌环C N键的伸缩振动峰红移了9 cm-1,并且强度也有很大程度提高.说明PANI与WC之间有化学键的作用,它们之间的化学键作用发生在C N键的N原子上.聚合反应优先在WC粒子表面进行,生成PANI包覆结构,并提出了PANI/WC复合物的形成机制.     

Cerium dioxide/polyaniline core-shell nanocomposites

The preparation of CeO2/polyaniline (CeO2/PANI) core-shell nanocomposites via chemical oxidation of aniline using CeO2 as an oxidant is reported. TEM, TGA, FT-IR, XPS, and conductivity measurement are used to characterize the resulting composites. TEM measurements reveal that the shape of PANI/CeO2 nanocomposites is different from CeO2 nanoparticles and fibular PANI oxidized with soluble oxidant. Electron diffraction (ED) patterns of CeO2/PANI nanocomposites reveal single crystal of CeO2. FT-IR spectra confirmed the formation of PANI; the amount of PANI in the nanocomposites is estimated by TGA results. The conductivities increase with the increasing ratio of PANI/CeO2. XPS results reveal that in the nanocomposites Ce4+ of CeO2 is reduced to Ce3+. In addition, the degree of protonation of polyaniline obtained from N 1s XPS results in cerium dioxide/polyaniline composites is about 48.52%.     

乳液聚合中聚苯胺膜形成的动力学研究

以(NH4)2S2O8(APS)为氧化剂,十二烷基苯磺酸(DBSA)同时为乳化剂和掺杂剂,采用乳液聚合方法制备聚苯胺膜(PANIfilm),用石英晶体微天平(QCM)实时监测聚苯胺膜的形成过程,并对其动力学过程进行研究.结果表明,聚苯胺成膜反应对APS是0.5级,对苯胺是1级,聚苯胺膜增长速率随温度的升高而增加,而聚苯胺膜的最终沉积量却减小,表观活化能Ea=41.15kJ/mol,与均相溶液聚合成膜法的结果相近;随着DBSA浓度的增加,聚苯胺膜增长速率减小,而最终的沉积量增大.     

原位聚合法制备PANI/PET导电织物及其性能分析

在聚酯纤维基材及其织物表面,原位聚合形成厚度约1~2μm聚苯胺包覆层,制得聚苯胺(PANI)/聚酯(PET)导电织物.PANI层优异的导电性能使之成为有广阔发展前景的柔性电磁屏蔽材料.正交试验分析研究了苯胺单体浓度、氧化剂:苯胺摩尔比、掺杂酸浓度、反应时间对PANI包覆层外观形态、与基体结合牢度以及导电性的影响.实验表明:在经适当前处理的PET基材表面,以苯胺单体浓度为0.25mol/L、氧化剂与苯胺摩尔比为1∶1、掺杂酸浓度0.5 mol/L、反应时间60 min、反应温度为0~20℃时制备的PANI/PET导电织物方阻最小,导电性最好;掺杂酸酸性越强,导电性越好.SEM、FTIR及XRD测试表明涤纶织物表面有均匀连续的聚苯胺膜存在.分析表明聚苯胺分子链中氧化结构与还原结构含量基本相等,说明聚苯胺渗入纤维内部,使纤维无定形区面积增加,结晶度减小.     

聚苯胺/碳化钨导电复合材料的合成

以苯胺和过硫酸胺为原料,采用原位聚合方法合成了聚苯胺/碳化钨(PANI/WC)导电复合材料。研究了反应体系中碳化钨的含量对复合材料电导率的影响,确定了较佳的聚合条件,并且通过FT-IR、XRD、XPS和DSC-TGA等手段对复合材料的结构和性能进行了表征和分析。结果表明:碳化钨(WC)的加入提高了聚苯胺的电子导电性能,复合材料中聚苯胺组分为无定型,WC的晶型在反应前后并未发生变化,复合材料的热稳定性好并且质子化程度更高。     

一种水中可溶性导电聚苯胺的制备与表征

分别以聚乙二醇(PEG)的水、乙醇溶液为反应媒介, 制备了Keggin结构杂多酸(H₄SiW₁₂O₄₀)掺杂的导电聚苯胺材料. 此聚苯胺经IR, XRD, UV-Vis光谱进行了表征, 并采用标准的四探针法对其电导率进行了测定. 同时系统地研究了杂多酸、氧化剂和单体的比例、反应混合体系温度的改变等对所合成聚苯胺的产率、导电率、水中溶解性等方面的影响. 结果表明, 在PEG乙醇溶液中制备的聚苯胺比在水溶液中制备的有较高的产率、电导率和溶解率. 其最高电导率可达到1.87 S/cm, 溶解率可达53%.     

Preparation and characterization of polyaniline-containing Na-AlMCM-41 as composite material with semiconductor behavior

Composite material formed from a mesoporous aluminosilicate, Na-AlMCM-41, with conducting polyaniline (PANI) has been synthesized by an in situ polymerization technique. Studies of aniline adsorption over mesoporous Na-AlMCM-41 synthesized in our laboratory allowed us to find the modes in which aniline interacts with the active sites of Na-AlMCM-41. In order to obtain the best reaction conditions to polymerize aniline onto Na-AlMCM-41, aniline was first polymerized to produce pure PANI. Hence, the oxidative in situ polymerization was carried out by two procedures, differing in the polymerization time and in static or stirring conditions. Studies of infrared spectroscopy and UV-vis spectroscopy indicated that higher polymerization time and static conditions allowed us to obtain mainly polyaniline in emeraldine form on the host. The N(2) isotherm of the polyaniline/Na-AlMCM-41 composite (PANI/MCM) indicated that the shape was similar to that of MCM, but the shift to saturation transition to lower partial pressure shows that the channels are occupied by PANI and they are now narrowed. The thermal properties of PANI, Na-AlMCM-41, and composite were investigated by TGA analyses and we found that the polymer shows higher thermal stability when it is forming the composite. Scanning electron microscopy indicated that PANI is not on the outer surface of the host. Conductivity studies show that PANI/Na-AlMCM-41 exhibits semiconductor behavior at room temperature and its conductivity was 7.0 x 10(-5) S/cm, smaller than that of pure polyaniline. PANI/Na-AlMCM-41 conductivity shows an increase as temperature increases. Magnetic measurements at room temperature confirmed that the composite has paramagnetic behavior; at lower temperatures the composite became diamagnetic.