Early stage pH profile: the key factor controlling the construction of polyaniline micro/nanostructures

During aniline chemical oxidative polymerization which accompanies a falling pH, the initial acidity as well as the early stage pH profile actually plays an important role in the formation of polyaniline (PANI) micro/nanostructures. By utilizing an interfacial polymerization system, transfer and dosage of the reactants were controlled to change acidity profile during the early stage of reaction, without introducing any extra electrolytes. The results showed that, even for the polymerization systems with identical conditions, significant increase on the early stage pH profile induced by accelerated reactants’ transfer had led to PANI exhibiting molecular structures and morphologies typically belonging to those synthesized with weak acidity. Effects of the early stage acidity profile on the final PANI products can be attributed to the initially formed oligomeric products, which can direct the self-assembly of subsequently produced polymers.     

Polyaniline/pillared montmorillonite clay composite nanofibers

In situ polymerization of aniline is done inside the pillared clay matrix. The nonswellable pillared clay confined matrix allows efficient polymerization that leads to nanofibrous morphology. As a result high polymer order and crystallinity is attained and is evident from XRD patterns. The strong interaction between the clay layers and polyaniline (PANI) is understood from FTIR and DRS spectra. Additionally these analytical results suggest that the prepared PANI is in the doped state. The PANI/pillared clay nanocomposite formation gives additional thermal stability to the polymer backbone and is clear from the DTG curves. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

聚苯胺/PE复合材料的制备探究

采用原位化学氧化聚合法制备苯胺/PE导电复合材料,使苯胺在基体高分子PE的水溶液中进行聚合,研究反应体系中聚苯胺的含量、反应时间、温度对复合材料电导率的影响,确定了较佳的聚合反应条件,并且通过红外对光谱复合材料的结构、光电性能和稳定性进行了表征和分析。     

Morphology control of chemically prepared polyaniline nanostructures: Effects of mass transfer

Chemical oxidative polymerization of aniline was carried out in a high viscosity reaction system, created by dissolving a high molecular weight, water-soluble polymer – polyethylene oxide – into the polymerization reaction. It was found that mass transfer, which likely influences the nucleation and growth of the polymerization products, has significant effects on the morphology of chemically prepared polyaniline (PANI) nanostructures. One-dimensional PANI nanostructures obtained in the high viscosity system had obviously smaller sizes and aspect ratios, as species diffusion was suppressed, especially with further increased system viscosity. The growth of PANI nanostructures appeared to be heavily diffusion-limited when aniline polymerization was carried out using a moderate oxidant or at very low monomer concentrations (e.g. 0.005 M) in the high viscosity system, resulting in “coral reef”-like PANI clusters. Promoting mass transfer for the polymerization carried out under very low monomer concentration in the high viscosity system was beneficial for preparation of uniform PANI nanofibers.     

Studies on heterogeneous nucleation effect of dispersing intercalated montmorillonite clay platelets in polyaniline matrix

In this article, a series of nanocomposite materials that consisted of emeraldine base (EB) of polyaniline (PANI) and montmorillonite (MMT) clay were prepared by effectively dispersing the inorganic MMT clay platelets into organic PANI matrix via in situ chemically oxidative polymerization. Organic aniline monomers were first intercalated into the interlayer regions of organophilic clay hosts and followed by an one‐step oxidative polymerization with ammonium persulfate as oxidant. The as‐synthesized PANI‐clay nanocomposite (PCN) materials were characterized by Fourier‐Transformation infrared spectroscopy and transmission electron microscopy. It should be noted that the EB of PANI in the presence of dispersed intercalated MMT clay platelets was found to display an observable enhancement in polymer crystallinity as compared with that of neat PANI based on series of investigations of wide‐angle powder X‐ray diffraction patterns and differential scanning calorimetric studies. This remarkable increase of polymer crystallinity might be resulted from the effective heterogeneous nucleation effect of dispersed clay platelets existed in PCN materials. The surface morphology study of PCN materials was further evaluated by polarizing optical microscopy, scanning electron microscopy, and atomic force microscopy. POLYM. COMPOS., 31:2049–2056, 2010. © 2010 Society of Plastics Engineers     

Cationic metalloporphyrins for synthesis of conducting,water-soluble polyaniline

Catalytic oxidative polymerization of aniline was performed using the tetrapyridylporphyrin (TPyP) complexes of iron (III), manganese (III) and cobalt (III). It was found that the cationic metalloporphyrin catalyzed the polymerization of aniline more efficiently than the anionic metalloporphyrins, when using aqueous H₂O₂. The reaction was carried out in the presence of sulfonated polystyrene (SPS) as a template at different pHs, ranging from 1 to 5, and the best results were obtained at pH 2. Formation of water-soluble polyaniline (PANI) was characterized by UV–vis, FT-IR spectroscopy and cyclic voltammetry (CV). FT-IR and UV–vis spectra confirm the formation of the conducting form of PANI. Cyclic voltammetry measurements demonstrate that the polymer has convenient electroactivity.     

On the structural and optical properties of gold–polyaniline nanocomposite synthesized via a novel route

Gold nanoparticle embedded polyaniline (PANI) was synthesized by in situ oxidative polymerization of monomer aniline. X‐ray diffraction and Fourier transform IR techniques were used to establish the structure of the gold–PANI composite. UV–visible absorption studies have shown that, along with the normal absorption peak of polyaniline, the composite has an absorption peak characterized by surface plasmon resonance. The presence of surface plasmon resonance is a signature of the nano size of the gold particles embedded in the PANI. Energy‐dispersive X‐ray spectroscopy (EDS) has revealed the elemental composition of the composite sample quantitatively. Raman spectroscopy studies have strengthened the presence of plasmon resonance. Single‐beam Z‐scan results confirm the third‐order optical nonlinearity associated with the nanocomposite. The present investigations show that gold nanoparticle embedded PANI composite can be of potential application in the fields of both linear and nonlinear optics. Copyright © 2012 Society of Chemical Industry     

纳米SiO2对原位分散聚合制备导电聚苯胺薄膜结构与性能的影响

在苯胺的化学氧化体系中,采用无机纳米微粒二氧化硅作为空间稳定剂,在玻璃基体表面直接制备了透明导电的聚苯胺薄膜,并与水溶性高分子聚乙烯吡咯烷酮(PVP)做稳定剂进行比较。采用SEM、紫外光谱、红外光谱和四探针电导率仪对薄膜的表观形貌、厚度、化学结构和电导率进行了表征。结果表明:稳定剂的存在有效抑制了溶液中宏观沉淀的生成,制得的薄膜表面光滑致密;与水溶性高分子聚乙烯吡咯烷酮(PVP)为稳定剂的情况相比较,纳米SiO2做稳定剂条件下,整个反应体系诱导期相对延长,反应速率相对缓慢,薄膜的生长速度也相对缓慢;薄膜的饱和厚度达到200nm左右,高于聚乙烯吡咯烷酮(PVP)做稳定剂的情况;所得薄膜的电导率要相对低一些,仍属于半导体范围;红外光谱分析发现制备的聚苯胺薄膜中无稳定剂存在,说明稳定剂未参与薄膜的生长聚合。     

Polyaniline nanotubes: conditions of formation

The courses of aniline oxidation with ammonium peroxydisulfate in aqueous solutions of strong (sulfuric) and in weak (acetic) acids, followed by temperature and acidity changes, are different. In solutions of sulfuric acid, granular polyaniline (PANI) was produced; in solutions of acetic acid, PANI nanotubes were obtained. The external diameter of the nanotubes was 100–300 nm, the internal cavity 20–100 nm, and the length extended to several micrometres. The morphology of PANI, granular or tubular, depends on the acidity conditions during the reaction rather than on the chemical nature of the acid. PANI nanotubes were also produced when aniline was oxidized in the absence of any acid. The bulk conductivity of PANI prepared in solutions of acetic acid was 0.08–0.27 S cm^?1, depending on the acid concentration. Protonated PANI prepared in sulfuric and acetic acids were deprotonated with ammonium hydroxide to obtain PANI bases and the ammonium salt of the protonating acid. FTIR spectroscopy showed the differences in the molecular structure of the PANI bases. Irrespective of whether the polymerization was performed in solutions of sulfuric or acetic acid, PANI had hydrogen sulfate counter‐ions only. The PANI morphology is thus not controlled by the nature of counter‐ions. The acidity of the reaction medium determines the protonation of monomer, oligomer and polymer species. The chemistry of aniline oxidation is likely to be affected especially by the protonation of an intermediate in the pernigraniline form. It is proposed that, in the course of aniline oxidation, pH‐dependent self‐assembly of aniline oligomers predetermines the final PANI morphology. Copyright © 2005 Society of Chemical Industry     

Development of polyaniline/zinc oxide nanocomposite impregnated fabric as an electrostatic charge dissipative material

The paper presents the electrostatic charge dissipative performance of conducting polymer nanocomposite impregnated fabric based on polyaniline (PANI) and zinc oxide nanoparticles (ZnO NPs). Conducting polymer nanocomposites (PANI‐ZnO NPs) were synthesized by in situ chemical oxidative polymerization of aniline by using sodium dodecyl sulfate as surfactant and HCl as dopant. Coating of PANI‐ZnO nanocomposites on the cotton fabric was carried out during polymerization. The interaction of ZnO NPs with the PANI matrix was determined by Fourier transform infrared spectra (FTIR), TGA, XRD, scanning electron Microscopy (SEM), high resolution transmission electron microscopy (HRTEM) and conductivity measurements. The conductivity of PANI‐ZnO NP coated fabric was found to be in the range 10^?3 ? 10^?6 S cm^?1 depending on the loading concentration of ZnO NPs in the polymer matrix. TEM and HRTEM images showed that the PANI‐ZnO nanocomposites had an average diameter of 25–30 nm and were nicely dispersed in the polymer matrix. Antistatic performance of the nanocomposite impregnated fabric was investigated by static decay meter and John Chubb instrument. The static decay time of the film was in the range 0.5 ? 3.4 s on recording the decay time from 5000 V to 500 V. This indicated that the nanocomposite based on PANI‐ZnO nanocomposites has great potential to be used as an effective antistatic material. © 2015 Society of Chemical Industry     

Electrically conductive polymer blends comprising polyaniline

Summary Electroactive polymer blends comprising polyaniline (PANI) as conductive constituent and poly(methyl methacrylate) (PMMA), polystyrene (PS) and methyl methacrylate-butadiene-styrene (MBS) copolymer as a thermoplastic constituent (TC) were prepared by using various techniques:in situ by oxidative polymerization of aniline in aqueous dispersions of the TC; by, coagulating of latex of TC in the acidic dispersions wherein PANI has been preliminary obtained; and by dry blending. It was shown that highest conductivity values revealedin situ prepared PANI/PMMA blends, where the intermolecular interactions between the constituents were suggested to be stronger than in the other systems studied.     

Effect of acids on in situ polyaniline film formation

The chemical oxidation of aniline with ammonium persulfate (APS) to form polyaniline (PANI) films has been studied in different aqueous acid media such as sulfuric, nitric, phosphoric and acetic acids. A comparison was made between the yields of PANI film deposition during the polymerization from these media with the corresponding one obtained previously from aqueous HCl solution. The degradation of the formed PANI films at the beginning of polymerization obtained at the higher concentrations of HCl is absent when the other acids under consideration were used. The effect of acid concentration on the yield and growth rate of the PANI film was studied. The variation in the yield and growth rate of the polymer films at different acid concentrations was explained on the basis of the electrostatic repulsion and the screening effects. Copyright © 2004 Society of Chemical Industry     

Study on soluble polyaniline by positron annihilation technique

The solubility, electrical conductivity, and other properties of polyaniline (PANI) are highly dependent on its oxidation state. In this work, polyaniline (PANI1) prepared by peroxodisulphate induced polymerization of aniline in acidic aqueous medium in presence of benzenediazonium chloride salt was found to exist in lower oxidation state than emeraldine form of PANI and was highly soluble in common organic solvents. This polymer was subjected to positron annihilation spectroscopic study to investigate the correlation between the oxidation state of the polymer and defect sites generated by different degrees of protonation that in turn affect its electrical conductivity. The positron annihilation lifetime data were resolved to yield a three‐component fit for PANI1 subjected to different levels of protonation. The variation of positron annihilation parameters (τ_1,I₂) and Doppler broadening parameters (R, S) as a function of protonation level of the polymer indicate the dopant sites increase initially on protonation and reach a saturation value after a certain level of acidification. The lower value of electrical conductivity and the intensity of intermediate lifetime component (I₂) for PANI1 compared to PANI in emeraldine oxidation state indicate the presence of lesser number of quinoid–imine moieties that could undergo protonation and thus yield highly enriched trapping centers. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

有机酸控制合成多级结构聚苯胺

在丙烯酸(AA)的溶液中,用三氯化铁为氧化剂氧化聚合苯胺,得到了多级纳/微米结构的聚苯胺(PANI)。讨论了丙烯酸和苯胺单体以及搅拌等条件对产物形貌及其结构的影响。研究发现,通过调整AA浓度,能可控的制备PANI球形和塔型多级结构。利用FTIR和XRD对产物分子结构进行了表征。     

Preparation of polystyrene/polyaniline core/shell structured particles and their epoxy‐based conductive composites

Polyaniline (PANI) was synthesized by chemical oxidative polymerization of aniline (ANI) in the presence of sulfonated crosslinked polystyrene (SCPS) particles in neutral water. The polymerization of ANI occurred preferentially on the surfaces of the SCPS particles, resulting in core/shell structured SCPS/PANI particles. The conductivities of the SCPS/PANI particles increased with increasing degree of sulfonation of the SCPS and with increasing ANI/SCPS weight ratios in the reactants. Conductive epoxy‐based composites were prepared by curing the blend of SCPS/PANI particles and epoxy resin with an aromatic amine curing reagent, indicating the core/shell structured particles were stable, to some extent, to alkaline environments, which will be of significant importance for the practical application of PANI in many cases. Copyright © 2006 Society of Chemical Industry     

Polyaniline synthesis catalysed by glucose oxidase

A novel method for synthesis of polyaniline (PANI) in aqueous media based on application of oxidizing-enzyme glucose oxidase (GOx) is reported. Hydrogen peroxide was produced during catalytic reaction of oxidizing-enzyme glucose oxidase from Penicillium vitale and initiated the polymerization of aniline. The increase in optical absorbance in the range of 340-700 nm was exploited for the monitoring of PANI polymerization process. The role of GOx in the formation of PANI, influence of the initial concentrations of GOx, and glucose and aniline monomer on the aniline polymerization rate was studied. The study of pH influence on polymerization rate showed that PANI polymerization was occurring in a broad pH range from the pH 2.0 to 9.0. Optimal polymerization/oligomerization temperature was found to be at 37 °C, which is also optimal for GOx-catalysed enzymatic reaction. After 10 days of continuous GOx-catalysed polymerization PANI appeared as colloid-microparticles visible by an optical microscope.     

Oxidative graft polymerization of aniline on Si(100) surface modified by plasma polymerization of glycidyl methacrylate

Modification of argon plasma-pretreated Si(100) surfaces via plasma polymerization of glycidyl methacrylate(GMA), followed by reactive coupling of the epoxide groups of the plasma deposited GMA chains with aniline, and finally by oxidative graft polymerization of aniline was carried out. An alternative approach involved the modification of the argon plasma-pretreated Si(100) surfaces via plasma polymerization of glycidyl methacrylate(GMA), followed by direct oxidative graft polymerization of aniline and thermal curing. The compositions and chemical states of the modified Si surfaces were characterized by X-ray photoelectron spectroscopy (XPS). The two methods of surface modification of the Si(100) surfaces produced similar results. The protonation-deprotonation behavior, the interconvertible intrinsic redox states, and the metal reduction behavior (the electroless plating of Pd from the Pd(II) ion solution) of the grafted polyaniline (PANI) chains on the Si(100) surface were grossly similar to those of the PANI homopolymer. The coupling of PANI to the covalently tethered GMA chains on the Si(100) surface was suggested by the cohesive failure inside the epoxy adhesive that was applied to the modified Si surface in an attempt to peel off the PANI layer from the GMA plasma-polymerized Si (GMA-pp-Si) substrate.     

Textile‐surface interfacial asymmetric polymerization

This research demonstrated that polymerization of aniline on cellulose produces chiroptically active composites. Polymerization of aniline in the presence of cotton fibers consisting of chiral cellulose are performed to prepare a polyaniline (PANI)/cotton composite. The polymerization is conducted at the cotton interface. The resultant PANI/cotton composite shows chiroptical activity elucidated with diffuse reflectance circular dichroism. In this reaction, textile‐surface interfacial asymmetric polymerization is performed with imprinting of chiral structure from the cotton as a natural chiroptically active polymer to the PANI. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41118.     

Controlled Synthesis of Linear Polyaniline Tubes and Dendritic Polyaniline Fibers with Stearic Acid

Summary One dimensional linear polyaniline (PANI) tubes (with cavity about 2-3 nm) and three dimensional dendritic PANI fibers (with different length) have been synthesized by chemical oxidation polymerization of aniline doped with stearic acid at room temperature. The shape of the as-prepared PANI could be easily tuned from line to dendriform and to network simply by controlling the concentrations of aniline and stearic acid. Scanning electron microscopy and transmission electron microscopy were applied to investigate the various kinds of morphologies. UV-vis absorption spectra and Raman spectra suggested these as-prepared PANI were in conductive emeraldine state and the various kinds of structures could affect their property.     

高电活性石墨烯/聚苯胺纳米复合材料的制备和表征

采用了一种简单有效地方法制备了高电活性的石墨烯/聚苯胺复合材料。首先,将苯胺在氧化石墨烯（GO）的水性分散液中氧化聚合,制备了氧化石墨烯/聚苯胺（GO/PANI）,再将GO/PANI与水合肼反应,制得还原-氧化石墨烯/聚苯胺（R（GO/PANI））。利用透射电子显微镜（TEM）,热失重分析（TGA）和循环伏安法（CV）对GO/PANI和R（GO/PANI的形貌,热稳定性和电化学性能进行了分析研究。结果表明,GO表面存PANI,且R（GO/PANI）的热稳定性和电活性都明显高于GO/PANI。