掺杂聚苯胺溶致液晶相的产生和表征

聚苯胺（PAN）具有共轭结构,从理论上满足形成液晶相的基本条件［1,2］．但由于聚苯胺难溶、难熔,长期以来对于聚苯胺溶液（尤其是浓溶液）或熔体的研究甚少．近年来,人们采用具有“增塑作用”的大分子功能质子酸对聚苯胺进行掺杂,获得可溶于多种有机溶剂中的掺杂态聚苯胺［3～5］．然而,聚苯胺溶液的结构与性能的特点及能否产生溶致液晶相等问题目前尚未见报道．为此,我们研究了十二烷基苯磺酸（DBSA）掺杂聚苯胺在有机溶剂中形成液晶相的条件,探讨了不同掺杂方法对PAN－DBSA的溶解性及形成液晶棺的影响;采用差式扫描量热分…     

聚苯胺热掺杂十二烷基苯磺酸的反应过程及其结构

与传统的质子酸掺杂相比，采用具有功能性的两亲大分子对聚苯胺（PAN）掺杂，可以使产物的加工性和稳定性大大提高［1～3]．十二烷基苯磺酸（DBSA）是研究得比较多的掺杂酸之一，其掺杂过程一般都采用辅助溶剂，由此而引起PAN与DBSA结合程度低、掺杂效率低、溶剂需后处理?..     

盐酸掺杂聚苯胺的制备及性能研究

本文用溶液聚合法制备盐酸掺杂聚苯胺,测定了体系酸度对聚苯胺电导率的影响,及盐酸掺杂聚苯胺在不同条件下经过热处理后的电导率,采用TGA、XRD等方法,研究了热处理过程对聚苯胺结构的影响。结果表明,当热处理温度为90℃时,电导率高于初始值,当热处理温度高于100℃时,电导率开始下降,到达220℃时,电导率下降了约4个数量级。在氮气中聚苯胺电导率的衰减比空气中小,聚苯胺经热处理后在浓硫酸中的溶解性会明显降低。本文还探讨了去掺杂、氧化和化学交联等盐酸掺杂聚苯胺的热降解机理。     

磁场及反应条件对十二烷基苯磺酸掺杂聚苯胺聚合成膜速率的影响

在恒定磁场(0.6 T)条件下, 采用过硫酸铵(APS)为引发剂, 在乳液体系中合成了十二烷基苯磺酸(DBSA)掺杂的聚苯胺(PAn). 借助石英晶体微天平(QCM)实时监测苯胺(An)在金电极表面聚合成膜过程, 探讨了磁场、APS浓度、DBSA浓度及反应温度对DBSA掺杂聚苯胺聚合成膜速率的影响. 实验结果表明, PAn在金电极表面的成膜速率随磁场强度的增加而增大; 由反应物浓度与PAn成膜速率的关系, 得出相应的动力学反应级数; 由PAn膜的增长速率与温度的关系, 得到成膜过程的活化能为41.08 kJ/mol. 考察了PAn聚合过程的UV-Vis光谱, 并与QCM所得的结果进行了比较. 结果显示, 在相同时间内, 磁场环境下合成的PAn的吸收强度大于无磁环境下合成的PAn.     

盐酸掺杂制备导电性聚苯胺的工艺优化研究

掺杂是获得高导电性聚苯胺的重要手段.本文采用盐酸进行掺杂,通过实验研究了不同条件下盐酸掺杂对聚苯胺基本性能的影响,优化了制备聚苯胺的工艺条件.当过硫酸铵与苯胺比为1时,聚合产率高达66.14%;当盐酸浓度为1.5mol/L时,室温下反应12h导电性最好.制备了聚苯胺样品,并对样品进行了FT-IR、SEM、XRD测试.结果均表明盐酸掺杂聚苯胺的反应主要发生在醌环上,掺杂后聚苯胺有一定的结晶性,且呈微纳米颗粒状、分布均匀,电导率达到1.29S·cm~(-1).正交试验得出的优化工艺为:盐酸浓度为1.0mol·L~(-1),氧化剂与苯胺单体摩尔比为1∶1,室温条件下反应4h.     

新型质子酸掺杂聚苯胺的合成及其电化学电容行为

用化学氧化聚合法制得了草酸掺杂聚苯胺(H2C2O4-PANI)和柠檬酸掺杂聚苯胺(C6H8O7-PANI),并与盐酸掺杂聚苯胺(HCl-PANI)做了对比研究.用红外光谱(FT-IR)、X射线衍射(XRD)和透射电镜(TEM)对掺杂聚苯胺的结构和形貌进行了表征.用循环伏安,恒流充放电和交流阻抗测试对材料在1 mol/L HCl溶液中的电化学电容行为进行了研究.结果表明:3种酸掺杂的聚苯胺具有不同的空间结构,电化学性能也有差异.与盐酸和柠檬酸掺杂的聚苯胺相比,草酸掺杂制备的聚苯胺表现出更优良的电化学电容行为,单电极比电容可达670 F/g.     

掺杂率对乳液聚合制备聚苯胺结构性能的影响

对乳液聚合的十二烷基苯磺酸(DBSA)掺杂聚苯胺(PAn)进行不同pH值溶液浸泡处理。采用元素分析、红外光谱分析、X射线衍射及热失重分析等手段，研究了不同掺杂率对PAn结构性能以及PAn在普通有机溶剂中的溶解性能和导电性能的影响。结果表明：随DBSA掺杂率的增加，PAn的电导率及其在三氯甲烷中的溶解度增加，带有烷基长链的DBSA使PAn形成以DBSA为间隔的有序层状结构；而且合成的PAn-DBSA热稳定性良好。     

盐酸和磺基水杨酸复合掺杂聚苯胺的热电性能

以苯胺为单体,过硫酸铵为氧化剂,采用化学氧化聚合法在盐酸和磺基水杨酸混合溶液中制备了导电聚苯胺。通过XRD、SEM、FTIR等分析手段,对所得产物的结构进行研究,并探讨在相同聚合条件下,不同的磺基水杨酸和盐酸的物质的量浓度比(cSSA∶cHCl)对聚苯胺热电性能的影响。结果显示,混合酸掺杂聚苯胺的电导率随cSSA∶cHCl的增加而增大,但Seebeck系数的变化趋势却与之相反。当cSSA∶cHCl=0.25:1时,掺杂态聚苯胺的功率因子在175℃时达到最大值为0.46μW.m-1.K-2,分别是相同条件下HCl和SSA掺杂聚苯胺的1.7和1.9倍。这表明适当配比的有机酸与无机酸混合掺杂比单一酸掺杂更有利于聚苯胺热电性能的提高。     

导电聚苯胺与Fe3O4磁性纳米颗粒复合物的合成与表征

对十二烷基苯磺酸(DBSA)掺杂的导电聚苯胺(PAn-DBSA)的氯仿溶液,在pH为中性的条件下,采用“修饰-再掺杂(Modification-re-doped)法”合成了含有Fe₃O₄磁性纳米颗粒的导电聚苯胺复合物的有机溶液.用FTIR,XRD,TEM,UV-Vis和SQUID等对所得复合物进行了表征,结果表明,该复合物呈现超顺磁性和半导体的导电性,并具有较好的透明性.     

绝缘聚合物对聚苯胺复合物导电性能的影响

将十二烷基苯磺酸掺杂的聚苯胺(PAn DBSA)与乙烯丙烯酸共聚物(EAA)或聚烯烃弹性体(POE)进行溶液共混制得了PAn DBSA/EAA或PAn DBSA/POE导电复合物。研究了绝缘聚合物的化学结构对聚苯胺导电复合物形态结构及电性能影响。结果表明,极性聚合物EAA中的羧基能与PAn形成氢键并发生掺杂作用,复合物中卷曲的PAn主链能充分展开,导致PAn/EAA复合物具有非常低的逾渗域值(1.5%),PAn含量为20.0%时,电导率高达7.1S/cm。POE为非极性共聚物,与极性较强的PAn相容性较差,导致PAn/POE复合物具有较高逾渗域值(5.0%),PAn含量为20.0%时,电导率仅为3.0×10-5S/cm。     

Enhancement of polyaniline’s electrical conductivity by coagulation polymerization

An effective and simple method was developed to prepare highly conductive polyaniline by coagulation polymerization. Depending on the coagulation reaction between aniline salts and lauryl sulfonate (SDS), not only was the polymerization rate of aniline monomers greatly decreased but also the doping efficiency of hydrochloric acid was effectively increased. Low polymerization rate provided enough time for the conformation adjustment of polyaniline chains and the diffusion of doping agent. Meanwhile, the doping efficiency of hydrochloric acid on polyaniline chains was effectively increased due to its easy diffusion among many vacancies, which were generated when SDS separated in the process of polymerization. Therefore, the electrical conductivity of polyaniline prepared by coagulation polymerization was increased more than ten times than that of polyaniline, which was prepared by conventional methods. In addition, the important factors to influence the preparation, such as SDS concentration, hydrochloride acid (HCl) concentration, content of ammonium persulfate (APS), and polymerization time were also investigated. When the molar ratio (aniline:SDS:HCl :APS) was set to 1.69:0.46:15.38:1, the conductivity of polyaniline reached 24.39 S/cm.     

Preparation and characterization of PVC/PANI conductive composite with extremely low percolation threshold

Aniline was polymerized in the presence of poly(vinyl chloride) (PVC) powders in hydrochloric acid to in situ prepare poly(vinyl chloride)/polyaniline (PVC/PANI) composite particles. UV‐vis spectra and FT‐IR spectra indicate PANI in PVC/PANI composite particles possessed a higher oxidation state with decreased aniline content in reactants. Both conductivity and impact strength of the dodecylbenzenesulfonic acid (DBSA) doped PANI composites (PVC/PANI‐DBSA), which were compression molded from the in situ prepared PVC/PANI particles, increase with the pressing temperature and decrease with the increase of DBSA doped PANI (PANI‐DBSA) loading. An excellent electric conductivity of 5.06 × 10^?2 S/cm and impact strength of 0.518 KJ/m² could be achieved for the in situ synthesized and subsequently compression molded composite. Copyright © 2004 John Wiley & Sons, Ltd.     

Calorimetric investigations of high density polyethylene/polyaniline composites

Summary Electrically conductive composites containing high density polyethylene (HDPE) and polyaniline (PANI) - dodecylbenzenesulfonic acid (DBSA) complex were prepared in situ by bulk oxidative polymerization of aniline (ANI) in presence of DBSA. Their thermal behaviour and crystallinity parameters were studied for the first time by using differential scanning calorimetry (DSC). It was found that the presence of the conductive complex does not affect the crystalline structure of the matrix polymer neither during in situ polymerization of ANI in powdered HDPE nor upon heating of HDPE/PANI·DBSA composite up to 180°C followed by fast cooling.     

Thermal degradation mechanism of dodecylbenzene sulfonic acid- hydrochloric acid co-doped polyaniline

Co-doped polyaniline (PANI) was synthesized in microemulsion by hydrochloric acid (HCl) and dodecylbenzene sulfonate (SDBS) then thermal treated in air at 160 and 200 °C for 0.5 h, respectively. The changes of structure, thermal stability, micromorphology and electrical conductivity after thermal treatment were studied by Fourier transformed infrared (FT-IR), Thermogravimetric analysis (TGA), X-ray diffraction (XRD), scanning electron microscope (SEM) and four-probe technique. It was found that the conductivity of PANI decreased about 50% after thermal treated at 160 °C, and droped by 2 orders of magnitude at 200 °C. This may be explained by that only a fraction of total mass of HCl losses during thermal treatment at 160 °C, but after heating at 200 °C, the dedoping of dodecylbenzene sulfonic acid (DBSA) along with cross-linking, chain scission and oxygen incorporation in a form of carbonyl groups take place, resulting in destruction of crystal structure, decrease of the emeraldine sequence, lower thermal stability and heterogeneous micromorphology.     

Structural Investigations of Polyaniline Prepared in the Presence of Dodecylbenzenesulfonic Acid

Structural studies of powdered polyaniline (PANI) prepared in aqueous medium by the oxidative polymerization of aniline in the presence of dodecylbenzenesulfonic acid(DBSA) were performed by means of DSC and WAXS. The influence of the alkyl side-chains on the structure and crystallinity of the as-synthesized PANI—DBSA and on the structural transitions taking place in PANI upon washing and heating were investigated. It was found that DBSA induces crystallinity in the rigid matrix of PANI, and residual crystalline phases were also observed after the deprotonation of PANI—DBSA. For the first time, a melting peak and a relaxation transition of non-cross-linked PANI were registered.This revised version was published online in November 2005 with corrections to the Cover Date.     

Preparation and properties of polyaniline codoped with ionic liquid and dodecyl benzene sulfonic acid or hydrochloric acid

Three nanosized polyaniline (PAn) powders doped with ionic liquid and dodecyl benzene sulfonic acid (DBSA) or hydrochloric acid have been prepared for the first time in an ionic liquid-water emulsion system. The oil-phase ionic liquid is used as both a monomer solvent and doped counterion. The effects of different counterions on the properties (molecular weight, electrical conductivity, glass transition temperature, electrochemical activity) of PAn are investigated. PAn codoped with 1-butyl-3-methylimidazolium hexafluorophosphate ionic liquid and DBSA shows the highest molecular weight (81 104 g mol^?1), the highest electrical conductivity (1.85 S cm^?1), the lowest glass transition temperature (181°C) and the highest redox reaction current density; PAn doped with an ionic liquid only exhibits the lowest conductivity (0.0018 S cm^?1) and a lower redox reaction current density. PAn codoped with ionic liquid and HCl shows higher conductivity. They also exhibit good electrochemical stability and charge-discharge performance. These indicate that codoping of different counterions under acidic conditions could improve the degree of oxidation and doping ratio of PAn and could result in high electrical conductivity and good electrochemical properties.     

Polyaniline/thermoplastic polyurethane blends: Preparation and evaluation of electrical conductivity

Conducting polymer blends whose undiluted components have different properties are promising materials for specific applications and have attracted interest in recent years. The aim of this study was to obtain and evaluate the electrical conductivity of polyaniline doped with dodecylbenzenesulfonic acid (PAni.DBSA)/polyurethane thermoplastic (TPU) blends. The PAni.DBSA was synthesized from DBSA-aniline (DBSAn) salt through an emulsion polymerization in tetrahydrofurane (THF) or in the presence of polyurethane thermoplastic solution, resulting in pure PAni.DBSA or PAni.DBSA/TPU blends. Blends of PAni.DBSA/TPU were also prepared through casting, at room temperature, after dissolving both components in THF as a common solvent. The insulator-conductor transition was very sharp and the percolation threshold was lower than 2.7 wt% of PAni.DBSA. The electrical conductivity of PAni.DBSA/TPU blends, prepared by both methods, reached maximum values at a PAni.DBSA concentration of 40 wt%, close to the value observed for the undiluted conducting polymer. However, for a PAni.DBSA content lower than 30 wt%, the electrical conductivity was dependent on the blend preparation method. Blends were characterized by infrared spectroscopy, thermogravimetric analysis (TG) and optical microscopy. The electrical conducting characteristics of the PAni.DBSA/TPU blends prepared using different procedures indicate a high potential for their successful application in electrical processes.     

Dielectric behavior of polyaniline synthesized by different techniques

Polyaniline doped with dodecylbenzenesulfonic acid (Pani.DBSA) was synthesized by different procedures: by a dedoping-redoping process, by one step inverted emulsion polymerization and by one step aqueous dispersion polymerization. The effect of these different techniques on the electric properties (dielectric constant, dielectric losses, and complex electric modulus) of the corresponding emeraldine base has been studied by thermal dielectric analyzer (DETA) in the temperature range −130 °C to 200 °C and in frequency range 0.03-10⁵ Hz. It was found that the preparation technique has significant influence on the dielectric properties of Pani. The different synthetic routes give rise to polyaniline with different distribution of electric relaxation process, indicating different chain structure. Emeraldine base from Pani.DBSA prepared by one step aqueous dispersion polymerization exhibits one single relaxation peak with narrow distribution whereas that prepared by inverted emulsion polymerization exhibits two relaxation peaks, indicating two-phase structure as indicated by a bimodal distribution of relaxation process. Emeraldine base from Pani.DBSA prepared by dedoping-redoping process presents an intermediary behavior. Percentage crystallinity of Pani.DBSA samples has also been investigated using wide-angle X-ray diffraction analysis. Pani.DBSA prepared by aqueous dispersion exhibited higher crystallinity degree, which agrees with the higher conductivity.     

Structure and properties of conducting bacterial cellulose-polyaniline nanocomposites

Conducting composite membranes of bacterial cellulose (BC) and polyaniline doped with dodecylbenzene sulfonic acid (PAni.DBSA) were successfully prepared by the in situ chemical polymerization of aniline in the presence of hydrated BC sheets. The polymerization was performed with ammonium peroxydisulfate as the oxidant agent and different amounts of DBSA. The composites were characterized by X-ray diffraction, attenuation reflectance Fourier transform infrared spectroscopy, scanning electron microscopy (SEM), impedance spectroscopy and small angle X ray scattering (SAXS). The highest electrical conductivity value was achieved by using a DBSA/aniline molar ratio of 1.5 because this condition provided a better penetration of PAni.DBSA chains inside the hydrated BC sheet, as observed by SEM. The in situ polymerization gives rise to conducting membranes with the surface constituted by different degree roughness as indicated by Nyquist plots obtained from impedance spectroscopy and confirmed by SAXS measurements. This preliminary work provides a new way to prepare cellulose-polyaniline conducting membranes which find potential applications as electronic devices, sensors, intelligent clothes, etc.     

Polyurethane/polyaniline and polyurethane‐poly(methyl methacrylate)/polyaniline conductive core‐shell particles: Preparation,morphology, and conductivity

Polyurethane/polyaniline (PU/PANI) and polyurethane‐poly(methyl methacrylate)/polyaniline (PU‐PMMA/PANI) conductive core‐shell particles were synthesized by a two‐stage polymerization process. The first stage was to produce a core of PU or PU‐PMMA via miniemulsion polymerization using sodium dodecyl sulfate (SDS) as the surfactant. The second stage was to synthesize the shell of polyaniline over the surface of core particles. Hydrogen chloride (HCl) and dodecyl benzenesulfonic acid (DBSA) were used as the dopant agents. Ammonium persulfate (APS) was used as the oxidant for the polymerization of ANI. Different concentrations of HCl, DBSA, and SDS would cause different conformations of PANI chains and thus different morphologies of PANI particles. UV–visible spectra revealed that the polaron band was blue‐shifted because of the more coiled conformation of PANI chains by increasing the concentration of DBSA. Besides, with a high concentration of DBSA, both spherical‐ and rod‐shape PANI particles were observed by transmission electron microscope, and the coverage of PANI particles onto the core surfaces was improved. The key point of formation of rod‐type PANI particles was that DBSA was served with a high concentration accompanied with the existence of HCl or SDS. The better coverage of PANI particles over the core surfaces by charging higher DBSA concentrations resulted in a higher conductivity of hybrid particles. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3902–3911, 2007