Photolithographic Patterning of a Conductive Polymer Using a Polymeric Photoacid Generator and a Traceless Removable Group

Summary: In the present communication we describe a photolithographic method to produce polyaniline (PANI) patterns using PANI modified with a traceless removable functional group (nitrosated polyaniline, PANI‐NO) and external inexpensive polymeric photoacid generators (poly(vinyl chloride), PVC). Therefore, residual sub‐products created by irradiation of the plate do not remain occluded in the polymeric films. The borders of the patterns are better defined than in the case of chemical lithography using inorganic acids as the hydrolyzing agent.

     

Nitrosonium-catalyzed decomposition of s-nitrosothiols in solution: a theoretical and experimental study

The decomposition of S-nitrosothiols (RSNO) in solution under oxidative conditions is significantly faster than can be accounted for by homolysis of the S-N bond. Here we propose a cationic chain mechanism in which nitrosation of nitrosothiol produces a nitrosated cation that, in turn, reacts with a second nitrosothiol to produce nitrosated disulfide and the NO dimer. The nitrosated disulfide acts as a source of nitrosonium for nitrosothiol nitrosation, completing the catalytic cycle. The mechanism accounts for several unexplained facets of nitrosothiol chemistry in solution, including the observation that the decomposition of an RSNO is accelerated by O(2), mixtures of O(2) and NO, and other oxidants, that decomposition is inhibited by thiols and other antioxidants, that decomposition is dependent on sulfur substitution, and that decomposition often shows nonintegral kinetic orders.     

Thin mesoporous polyaniline films manifesting a water-promoted photovoltaic effect

Photovoltaic cells composed of thin mesoporous polyaniline films sandwiched between an indium-tin oxide anode and aluminium cathode have been fabricated. The cells show an increase in the photo-generated open-circuit voltage (V _oc) from 0.2 V to 0.6 V and stable-in-time V _oc generation following the addition of water containing highly hydrated ions, e.g. tap water.We explain the waterpromoted photo-voltaic effect by the polarity of the water environment. Theoretical calculations show that increasing the solvent polarity increases the energy of the electronic transition related to the measured V _oc. The stable-in-time V _oc generation could be explained by the increase in the lifetime of the excitons as well as by their more efficient dissociation in the interpenetrating network of polyaniline and water. The penetration of water into the mesoporous polyaniline films is promoted by the presence of highly hydrated ions.     

In situ fabrication of a water-soluble, self-doped polyaniline nanocomposite: the unique role of DNA functionalized single-walled carbon nanotubes

Dispersion of carbon nanotubes into solvents affects their surface chemistries, electronic structures, and subsequent functionalization. In this Communication, a water-soluble self-doped polyaniline nanocomposite was fabricated by in situ polymerization of the 3-aminophenylboronic acid monomers in the presence of single-stranded DNA dispersed- and functionalized-single-walled carbon nanotubes. For the first time, we found that the carbon nanotubes became novel active stabilizers owing to the DNA functionalization. The nanotubes reduced the polyaniline backbone from the unstable, degradable, fully oxidized pernigraniline state to the stable, conducting emeraldine state because of their reductive ability, which could improve the chemical stability of the self-doped polyaniline. Electrical measurements demonstrate that the conductivity of the nanocomposite was much higher than that of the pure self-doped polyaniline in both acidic and neutral solutions.     

Preparation and Characterization of Some Substituted Benzyl N-Nitrosocarbamates Containing an N-2-(Methylthio)ethyl or a Bis(2-aminoethyl)sulfide Functionality

The synthesis and characterization of some substituted benzyl N-nitrosocarbamates with an N-2-(methylthio)ethyl or a bis(2-aminoethyl)sulfide functionality is reported, as a part of a long-term goal to design and prepare novel photolabile structures that could be used as substances for controlled release of alkylating and/or crosslinking agents. The synthesis was accomplished by reaction of benzyl chloroformates with the corresponding amines, resulting in the preparation of carbamates. The latter were subsequently nitrosated, utilizing two different N-nitrosation methods, to yield the target structures.     

Controlled electrophoretic patterning of polyaniline from a colloidal suspension

We present a method for controlled deposition of polyaniline from colloidal suspensions. Stable suspensions of polyaniline colloids (approximately 115 nm in diameter) were formed by dispersing polyaniline/formic acid solution into acetonitrile. It was demonstrated that the positively charged polyaniline colloids can be electrophoretically deposited onto various substrate materials such as platinum and ITO, forming continuous ultrathin films. We examined the film morphology, as well as the effects of process parameters, such as deposition time, colloid concentration, and applied voltage, on the deposition efficiency. Furthermore, the efficacy of the technique was illustrated by electrophoretically patterning polyaniline thin films onto selected individual micrometer-scale sensing elements within a microfabricated sensor array, and by further demonstrating its sensitivity to gaseous analytes including water and methanol.     

电化学制备有序聚苯胺纳米线阵列

以有序碳纳米管阵列电极为基底电极,在硫酸或高氯酸溶液中,分别探明不同电化学聚合方法以及苯胺单体浓度对聚苯胺形貌的影响. 结果表明：采用循环伏安法无法制备出聚苯胺纳米线;而应用恒电位法虽可制得聚苯胺纳米线,但纳米线不能形成有序阵列;只有应用恒电流方法,并且以高浓度苯胺的高氯酸溶液作为聚合溶液,方能制得有序聚苯胺纳米线阵列.     

Dilute anionic surfactant solution route to polyaniline rectangular sub-microtubes as a novel nanostructure

A facile and low-cost approach has been developed for tailoring polyaniline rectangular sub-microtubes as a novel nanostructure of a conducting polymer in dilute sodium dodecyl sulfate (SDS) solution by the oxidation polymerization of aniline at room temperature. It was found that the size and uniformity of polyaniline rectangular sub-microtubes could be appropriately adjusted by tuning the concentration of aniline and the molar ratio of oxidant to aniline, respectively. The morphological evolution of rectangular sub-microtubes under different reaction times has been followed, and a possible formation mechanism has also been discussed in this report. The directing role of other anionic surfactants with -SO3(-) as the hydrophilic group for constructing polyaniline rectangular sub-microtubes has been investigated in detail.     

Effect of carbon black content on electrical and microwave absorbing properties of polyaniline/carbon black nanocomposites

Carbon black coated with polyaniline, forming a core-shell structure, was synthesized by in situ polymerization at different carbon black contents (5-30 wt.%) and introduced into epoxy resin to be a microwave absorber. The spectroscopic characterizations of the formation processes of polyaniline/carbon black composites were studied using Fourier transform infrared, ultraviolet-visible spectrophotometer, X-ray diffraction, scanning electron microscopy, transmission electron microscopy and electron spin resonance. Microwave absorbing properties were investigated by measuring reflection loss in the 2-18 and 18-40 GHz microwave frequencies range using the free space method. The results showed that a wider absorption frequency range could be obtained by adding different carbon black contents in polyaniline.     

从混合间对甲酚制备杀螟硫磷

O,O-二甲基-O-(3-甲基-4-硝基苯基)硫代磷酸酯商品名杀螟硫磷(Sumithion),它低毒高效,杀虫谱广,毒性只有甲基1605的1/50。     

聚苯胺/纳米二氧化锰复合材料Ⅰ.原位氧化合成制备

用固相合成法制备了纳米二氧化锰(nm-MnO2),并通过原位聚合法制备了聚苯胺／纳米二氧化锰复合材料。研究结果表明：在苯胺／nm-MnO2的盐酸反应体系中,nm-MnO2可以使苯胺氧化聚合。在一定的nm-MnO2用量下,聚苯胺的产率随苯胺添加量的增加而下降,nm-MnO2在产物中的含量也随之下降,且含量很低。在苯胺：／nm-MnO2／过硫酸铵的反应体系中,研究了Nm-MnO2通过两种不同的加料方式原位制备PA-NI／nm-MnO2复合材料的合成条件。第一种方式为nm-MnO2和过硫酸铵同时与苯胺混合,一起参与苯胺的氧化聚合。第二种方法是先将过硫酸铵和苯胺混合,3min后再将nm-MnO2加入反应体系中。研究表明：第一种加料方式得到的队NI／nm-MnO2中nm-MnO2的含量很低;第二种加料方式可以得到高nm-MnO2含量(w=0．14-0．73)的产物,其电导率约10^-4S／cm。     

聚苯胺/金属纳米粒子复合物的制备及性能

基于国内外最新研究文献及本课题组研究工作,从发展历史、制备方法、多功能性方面系统综述了近年来发展起来的聚苯胺/金属纳米粒子复合物。在聚苯胺基体中引入金属纳米粒子的方法可归纳为3大类：原位复合法、直接共混法和层层自组装法。所形成的有机聚苯胺和无机金属杂化复合物不仅能保留各自原有的特异性能,而且二组分之间还存在着相互协同作用,能够极大地提升基体聚苯胺材料的性能,电导率最高可提高100倍,电氧化催化电流最高可提高10倍。分散在聚苯胺膜中的极少量铂微粒就能使不锈钢板的腐蚀电位稳定在钝化区域。聚苯胺/金属纳米粒子复合物所表现出的突出的固有电导性、优异的反应催化性和极强的金属防腐性,使其跻身于为数不多的新型高性能复合材料之列,显示出了诱人的应用前景。     

UV and visible light controllable depletion zone of ZnO-polyaniline p-n junction and its application in a photoresponsive sensor

In this communication, we report that the depletion zone thickness of the p-n junction between an n-type ZnO and a p-type polyaniline could be controlled by UV and visible light illumination. Based on this princile, photoresponsive sensors were constructed by combining polyaniline thin film and ZnO nanorods. Different from pure ZnO nanomaterials whose conductivity increases when they are exposed to UV illumination, the conductivity of the photoresponsive sensor studied in this communication decreased when the UV light was turned on. The surface modification of ZnO could switch the wavelength of the response light from UV to visible light.     

Reversible encapsulation of nanometer-size polyaniline and polyaniline-Au-nanoparticle composite in starch

In this paper we report a new method of solubilization of polyaniline and polyaniline-Au-nanoparticle composite by encapsulating nanometer-size particles in starch. The solubilization was carried out in the presence of ultrasonic waves. We also report that the encapsulation was completely reversible and the dissolved polyaniline as well as the composite could be recovered by replacement with molecular iodine. In addition, the polymer particles could also replace molecular iodine from starch-iodine complex. UV-Visible and Fourier transform infrared (FTIR) spectroscopic measurements established the reversible nature of encapsulation. Transmission electron microscopic measurements showed that the sizes of the particles encapsulated in starch were on the order of 10-20 nm for both polyaniline and Au-nanoparticle-polyaniline composite particles. X-ray diffraction evidenced the presence ofAu-nanoparticles in the starch-polyaniline-Au-nanoparticle composite. Finally, we also mention here that the dissolved polyaniline could also be recovered as a precipitate by enzyme (diastage) hydrolysis of the polyaniline encapsulating starch.     

Assembly of tobacco mosaic virus into fibrous and macroscopic bundled arrays mediated by surface aniline polymerization

One-dimensional (1D) polyaniline/tobacco mosaic virus (TMV) composite nanofibers and macroscopic bundles of such fibers were generated via a self-assembly process of TMV assisted by in-situ polymerization of polyaniline on the surface of TMV. At near-neutral reaction pH, branched polyaniline formed on the surface of TMV preventing lateral association. Therefore, long 1D nanofibers were observed with high aspect ratios and excellent processibility. At a lower pH, transmission electron microscopy (TEM) analysis revealed that initially long nanofibers were formed which resulted in bundled structures upon long-time reaction, presumably mediated by the hydrophobic interaction because of the polyaniline on the surface of TMV. In-situ time-resolved small-angle X-ray scattering study of TMV at different reaction conditions supported this mechanism. This novel strategy to assemble TMV into 1D and 3D supramolecular composites could be utilized in the fabrication of advanced materials for potential applications including electronics, optics, sensing, and biomedical engineering.     

Emulsion Polymerization Pathway for Preparation of Polyaniline‐Sulfate Salt,using Non Ionic Surfactant

In this work, aniline was polymerized directly to the polyaniline‐sulfate salt without using a protonic acid. The polyaniline‐sulfate salt was prepared by emulsion polymerization, using a non ionic surfactant such as poly(ethylene glycol)–block poly(propylene glycol)‐block poly(ethylene glycol). In the aniline oxidation process, to give the polyaniline salt by ammonium persulfate, the sulfate ion is generated from ammonium persulfate and doped on to the polyaniline. Ammonium persulfate acts both as an oxidizing agent, as well as the protonating agent in the aniline polymerization process, to give the polyaniline salt. This result indicates that the effect of sulfate ion, generated by ammonium persulfate during oxidation of aniline to the polyaniline salt, may be taken into consideration in the polymerization process of aniline.     

Effect of ionizing radiation on polyaniline solutions

This communication presents the optical studies associated with transition doped (metallic)-neutral (semiconductor or insulator) state for conducting polymers. Special attention is focused on the electronic properties of polyaniline. The interconversion of different oxidation states of polyanilines has been studied by chemical and radiolytic methods. The polyaniline system is described by three sets of chromophores of three different oxidation states: fully reduced leucoemeraldine base (LB), partially oxidized emeraldine base (EB), and fully oxidized pernigraniline (PB). Each oxidation state can exist in its protonated form by treatment with an acid. All members of polyaniline family are spectroscopically distinguishable. The radiolytic study presents evidence that the polyaniline can exist in a continuum of oxidation states. The highly conducting form of polymer, i.e. emeraldine salt can be converted by using ionizing radiation into leucoemeraldine salt. The leucoemeraldine base is the final product of radiolysis of emeraldine base solution. The fully oxidized form of polyaniline can also be obtained by the irradiation of EB in the presence of CCl₄ or chlorobenzene.     

Pyridinium chlorochromate oxidation route to polyaniline

In this work, for the first time, pyridinium chlorochromate is used as an oxidizing agent inorder to oxidize aniline to polyaniline salts via an aqueous polymerization pathway in the presence of protic acids such as sulfuric, nitric, hydrochloric and phosphoric acid. The polymer samples were characterized by infrared, electronic absorption spectral, elemental analysis, conductivity, density and water absorption measurements. The results of the polyaniline salts prepared by pyridinium chlorochromate as an oxidizing agent were compared with that of the polyaniline salt prepared by ammonium persulfate. Generally, aniline is oxidized using ammonium persulfate as an oxidizing agent, which is unstable. In this work, pyridinium chlorochromate is used to oxidize aniline to polyaniline salt and the polymerization reaction could be completed in 30 min. Copyright © 2003 John Wiley & Sons, Ltd.     

Synthesis of a magnetoactive compound based on iron(II) sulfate

A method for synthesis of a magnetoactive compound based on iron(II) sulfate in the presence of nitrosated lignosulfonates at temperature of 20 to 50°C is suggested. The method yields a magnetoactive compound with high relative magnetic susceptibility.     

界面聚合法合成手性掺杂剂诱导螺旋形聚苯胺纳米纤维

以手性试剂D-樟脑磺酸(D-CSA)和L-樟脑磺酸(L-CSA)为掺杂剂和构象诱导剂,采用界面聚合法合成了螺旋形聚苯胺纳米纤维。通过FESEM、TEM、FTIR和UV-Vis吸收光谱等测试技术对螺旋形聚苯胺纳米纤维结构进行了表征。结果表明,所得聚苯胺纤维具有螺旋形构象,形貌均一,平均直径约为50nm,长度为300～600nm,具有较高的长径比(6:1～12:1)。在水溶液中,聚苯胺纳米纤维以伸展的螺旋形分子链构象存在,调节溶液的pH值,螺旋形聚苯胺纳米纤维表现出可逆的掺杂和脱掺杂性质。循环伏安(CV)测试表明,螺旋形聚苯胺纳米纤维在0.5mol/LHCl溶液中表现出良好的电化学活性。