Preparation of conductive polyaniline/chlorosulfonated polyethylene composites via in situ emulsion polymerization and study of their properties

The conductive composites of polyaniline (PAn) and chlorosulfonated polyethylene (CSPE) were prepared by polymerization of aniline in the presence of CSPE, using a direct, one‐step in situ emulsion polymerization method. The polymerization of aniline was performed in an emulsion comprising water and xylene containing CSPE in the presence of dodecylbenzene sulfonic acid, which acts both as a surfactant and a dopant for PAn. The composites can be processed by either melt method (MP) or solution method (SP). Conductivity of the composites obtained by different processing methods shows different percolation thresholds: 14 wt % for MP samples and 22 wt % for SP samples. At the same content of PAn, the conductivity of MP composites is higher than that of SP composites. The relationships between mechanical properties and PAn content obtained by the two different processing methods were also investigated. When PAn content of MP samples is between 12 and 18 wt %, the composites behave like a thermoplastic elastomer with tensile strength at 6–8 MPa, ultimate elongation > 400% and permanent set < 30%. The conductivity of composites obtained by SP method after secondary doping with m‐cresol is about 6 orders of magnitude higher than the original at below 18 wt % PAn content and the percolation threshold for conductivity is lowered to 3 wt % PAn content. The composite shows no electrochromic activity in acidic solution of LiClO₄ in propylene carbonate, but after secondary doping exhibits electrochromic activity even in neutral electrolyte. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 845–850, 2000     

Conductive polyaniline–polythiophene/poly(ethylene terephthalate) composite fiber: Effects of pH and washing processes on surface resistivity

A conductive polyaniline (PAn)–polythiophene (PTh)/poly(ethylene terephthalate) (PET) composite fiber was prepared by polymerization of aniline and thiophene in the presence of PET fibers in an organic medium with FeCl₃. The effects of polymerization conditions, such as polymerization medium, mol ratios of aniline/thiophene and FeCl₃/aniline‐thiophene as well as polymerization temperature and time, were investigated on PAn–PTh content (%) and surface resistivity of the composite. The composite with the lowest surface resistivity (1.30 MΩ/cm²) was obtained by polymerization of aniline and thiophene (1/3 mol ratio) in acetonitrile/chloroform (1/5 volume ratio) at 20°C. The surface resistivity of the PAn–PTh/PET composite containing 4.8% PAn–PTh was increased from 1.9 MΩ/cm² to 270 MΩ/cm² at pH 11. The washing durability of the composites was determined with domestic and commercial laundering processes by monitoring the surface resistivity and morphology. The composite was also characterized with FTIR, TGA, elemental analysis, optic microscope and SEM techniques. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41979.     

不同金属离子及胺中和的磺化丁基橡胶离聚体的性能

研究了不同金属离子及胺中和的磺化丁基橡胶离聚体的熔融流动性及力学性能。结果表明,随着硬脂酸锌加入量的增加,锂离聚体的熔融黏度降低,拉伸强度增大;随离聚体中磺酸基含量的增加,锂离聚体的熔融黏度和拉伸强度增大。对于一价金属离子中和的离聚体,其熔融黏度及拉伸强度随着离子电位的降低而减小;对于二价金属离子中和的离聚体,随着离子电位的下降及共价性的增加,熔融黏度下降而拉伸强度增大。用胺中和的离聚体,硬脂酸锌的影响较小,未加硬脂酸锌的离聚体具有较高的扯断伸长率及较低的永久变形,是良好的热塑性弹性体;随离聚体中磺酸基含量的增加,乙胺离聚体的拉伸强度增大。对于不同胺中和的离聚体,其拉伸强度按下列顺序依次降低：乙胺,三乙胺,二乙胺;乙胺,己胺,十二胺,十八胺。     

Change of conductivity of polyaniline/(styrene–butadiene–styrene) triblock copolymer composites during mechanical deformation

A measuring method for a conductivity change through a current change during extension deformation or compression deformation of conductive elastomeric composites composed of a polyaniline (PAn)/styrene–butadiene–styrene (SBS) triblock copolymer was established. The composites were prepared by in situ emulsion polymerization of aniline in the presence of SBS using dodecylbenzene sulfonic acid (DBSA) as an emulsifier and a dopant. The product was melt‐processed (MP), solution‐processed (SP), or secondary doped with m‐cresol (SSP). The results for measurement of the conductivity change of the composites processed by the three different methods showed that for the MP and SP samples conductivity increases with extension, whereas for the SSP sample when the PAn content is lower than the percolation threshold, conductivity diminishes with increasing extension, but when the PAn content exceeds the percolation threshold value, conductivity followed an empirical equation with a maximum value. During compression, the conductivities of most of the MP, SP, and SSP samples exhibited a maximum value with change of the compression force, except the MP sample with a higher PAn content, the conductivity of which increased with the compression force. All the differences are related to their different morphological structures. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 2156–2164, 2000     

Electrically conductive textiles by in situ polymerization of aniline

Two methods of obtaining electrically conductive fabrics by in situ polymerization of aniline were compared. Conductive fabrics were prepared by immersing the nylon 6 fabrics in 100% aniline or an aqueous hydrochloride solution of aniline followed by initiating successive polymerization in a separate bath (DPSB) or in a mixed bath (DPMB) of oxidant and dopant solution with aniline. In each case, the polymerization conditions were optimized to obtain the maximum quality of polyaniline (PAn) on the fabrics. The higher conductivity of composite fabrics, whose value reached up to 0.6 × 10⁻¹ s/cm, was obtained by the DPMB process. Moreover, this method induced the least decrease in the degree of crystallinity as compared to the DPSB process. The serviceability of the PAn–nylon 6 composite fabrics was also evaluated. No significant changes in the conductivity were observed after abrading the composite fabrics over 50 cycles and multiple acid and alkali treatment. The stability of conductivity was slightly decreased by less than 1 order after exposure to light for 100 h, but it was significantly decreased after washing with detergent. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 2094–2101, 1999     

Melt synthesis of sulfonated EPDM ionomers in batch and continuous processes

Zinc-neutralized sulfonated EPDM ionomers (Zn-SEPDM) were prepared by batch and continuous melt sulfonation processes, and the ionomer products were compared with ionomers synthesized by sulfonation of EPDM in homogeneous solution. The efficiency of a batch melt sulfonation using an intensive mixer as a reactor was comparable to that of the solution sulfonation process, but the efficiency of the melt sulfonation in a twin-screw extruder was considerably lower, which was thought to be a consequence of a relatively short reaction residence time due to limitations of the equipment. Melt neutralization was not complete, which produced a dark colored product. However, the incomplete neutralization and the color of the product did not affect the mechanical properties of the melt sulfonated ionomers, which were comparable to those of ionomers made by conventional solution sulfonation. The metal sulfonate concentration alone determined the mechanical properties of the ionomer. Melt sulfonation of Zn-SEPDM ionomers by batch or continuous melt processes appears to be a practical alternative to solution sulfonation, but further optimization of the melt sulfonation processes is needed to ensure uniform sulfonation and complete neutralization.     

Electrochemically oxidative polymerization of aniline in aromatic copolyamide matrix

Composite films from polyaniline (PAn) and a copolyamide, poly(p-phenylene terephthalamide/diphenylether terephthalamide) (PPDTA), have been obtained by the electrochemical polymerization of aniline on a PPDTA/Pt (or Ni, stainless steel) working electrode in water or a mixed-solvent electrolyte solution. This PAn/PPDTA composite has higher mechanical properties than does the PPDTA matrix and the electrical conductivity close to pure PAn. The electrochemical polymerization of aniline can be carried out only in the electrolyte solution with PH < 2. The PAn/PPDTA film is electroactive material and very stable in air. © 1993 John Wiley & Sons, Inc.     

Preparation and characterization of polyaniline–polypyrrole composite from polyaniline dispersions

Polyaniline–polypyrrole (PANI‐PPy) composite was prepared by in situ polymerization of pyrrole in PANI dispersion using FeCl₃·6H₂O as oxidant and sodium dodecyl benzene sulfonate (SDBS) as surfactant. Different synthesis conditions of PANI dispersion including the relative concentration of aniline and SDBS and the amount of acid (HCl) on the morphology and conductivity of the resulting composites were investigated. Fourier transformation infrared (FTIR) spectra, X‐ray photoelectron spectroscopy (XPS), thermal gravimetric analysis (TGA), X‐ray diffraction (XRD) patterns, and contact angles of the composites showed there existed certain interaction between PANI (or PANI‐SDBS) and PPy. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 3523–3529, 2007     

Synthesis and mechanical properties of poly(styrene-b-lsobutylene-b-styrene) block copolymer lonomers

Linear and three-arm star poly(styrene-b-isobutylene-b-styrene) (PS-PIB-PS) block copolymer ionomers possessing various counterions and levels of sulfonation were synthesized by sulfonating the polystyrene blocks of PS-PIB-PS block copolymers. Analysis of compression-molded films of the ionomers showed that the incorporation of sulfonate groups into the polystyrene blocks of these materials resulted in an increase in tensile strength, a decrease in elongation at break, and a persistence of elastic properties to much higher temperatures as compared with unsulfonated precursors. Among all counterions studied, zinc resulted in the strongest ionomers and potassium yielded the most easily processed ionomers. Dynamic mechanical analysis showed that the block copolymer ionomers possessed a phase-separated morphology; however, anomalous relaxations observed during the first heating cycle, but that were substantially reduced or completely absent in subsequent cycles, implied that strong ionic interactions were causing reduced processability and the formation of nonequilibrium morphologies. The observed relaxations were interpreted to be domain rearrangements brought about by the thermal energy supplied by the dynamic experiment. Annealing of films of relatively low ionic contents yielded viscoelastic behavior that was consistent with an equilibrium morphology characterized by phase-separated, partially sulfonated polystyrene domains of the same density and size as the polystyrene domains of the unsulfonated precursor. Compression molded films of high ionic content yielded a higher rubbery plateau modulus than the unsulfonated precursor, suggesting a different morphology. Solution-cast films of zinc ionomers exhibited two values for the rubbery modulus, a higher values at temperature below the T_g of polystyrene and a lower value at temperature above the T_g of polystyrene. Thermogravimetric analysis revealed the major mass-loss process of the parent, linear block copolymer at 417°C (mid-point) and of the tetramethyl ammonium ionomer at 431°C.     

High styrene–rubber ionomers,an alternative to thermoplastic elastomers

High styrene rubber ionomers were prepared by sulfonating styrene–butadiene rubber of high styrene content (high styrene rubber) in 1,2‐dichloroethane using acetyl sulfate reagent, followed by neutralization of the precursor acids using methanolic zinc acetate. The ionomers were characterized using X‐ray fluorescence spectroscopy, Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance spectroscopy (NMR), dynamic mechanical analysis (DMA), and also by the evaluation of mechanical properties. The FTIR studies of the ionomer reveal that the sulfonate groups are attached to the benzene ring. The NMR spectra give credence to this observation. Results of DMA show an ionic transition (T_i) in addition to glass–rubber transition (T_g). Incorporation of ionic groups results in improved mechanical properties as well as retention of properties after three cycles of processing. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2294–2300, 2002     

Preparation,characterization, and some properties of ionomers from a sulfonated styrene–butadiene–styrene triblock copolymer without gelation

The conditions for the sulfonation of a highly unsaturated styrene–butadiene–styrene triblock copolymer (SBS) in cyclohexane containing a small amount of acetone with acetyl sulfate made by sulfuric acid and acetic anhydride without gelation were studied. After neutralization with metallic ions, the ionomers were characterized with IR spectrophotometry, dynamic mechanical analysis, and transmission electron microscopy. The melt flow, solution properties, and mechanical properties of the ionomers were studied. The results showed that gelation occurred during the sulfonation of SBS in cyclohexane at a 5–10% concentration without acetone, whereas in the presence of 5–10 vol % acetone, sulfonation proceeded smoothly without gelation. Transmission electron microphotographs of the lead ionomer indicated the presence of ionic domains. A dynamic mechanical spectrum showed the presence of three transition temperatures: ?82.9, 68, and 96.5°C. The melt viscosity of the ionomer increased with the sulfonate content. The melt viscosity of the different ionomers neutralized with different cations seemed to decrease with decreasing ionic potential for both monovalent cations and divalent cations The solution viscosity of the sodium‐sulfonated ionomer increased with increasing sulfonate content. The ionomer still behaved as a thermoplastic elastomer and showed better mechanical properties than the original SBS. The tensile strength of the different ionomers decreased as follows. For the monovalent cations, it decreased with decreasing ionic potentials: Li⁺ > Na⁺ > K⁺. For the divalent cations, it decreased with increasing ionic potentials: Pb²⁺ > Zn²⁺ > Mg²⁺. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1398–1404, 2005     

Physicomechanical and dielectric properties of magnesium and barium ionomers based on sulfonated maleated styrene‐ethylene/butylene‐styrene block copolymer

Ionomers, containing both carboxylate and sulfonate anions on the polymer backbone, based on metal cations like Mg⁺² and Ba⁺² were prepared by sulfonating maleated styrene‐ethylene/butylene‐styrene block copolymer, hereafter referred to as m‐SEBS, followed by its neutralization by metal acetates. Infrared spectroscopic studies reveal that sulfonation reaction takes place in the para position of the benzene rings of polystyrene blocks and metal salts are formed on neutralization of the precursor acids. Dynamic mechanical thermal analyses show that sulfonation causes increase in T_g of the rubbery phase of m‐SEBS and decrease in tan δ at T_g of the hard phase, along with formation of a rubbery plateau. The changes become more pronounced on neutralization of the sulfonated maleated SEBS, and the effect is greater in the case of Ba salt. Dielectric thermal analyses (DETA) show that incorporation of ionic groups causes profound changes in the dielectric constant (ϵ′) of m‐SEBS. In addition to the low temperature glass–rubber transition, the plot of ϵ′ vs. temperature shows occurrence of a high‐temperature transition, also known as the ionic transition. Activation energy for the dielectric relaxation could be determined on the basis of frequency dependence of the ionic transition temperature. Two values of the activation energy for the dielectric relaxation refer to the presence of two types of ionic aggregates, namely multiplets and clusters. Incorporation of the ionic groups causes enhancement in stress–strain properties as well as retention of the properties at elevated temperatures (50° and 75°C), and the effect is more pronounced in the case of Ba ionomer. Although sulfonated ionomers show greater strength than the carboxylated ionomers, the sulfonated maleated ionomers show higher stress–strain properties in comparison to both sulfonated and carboxylated ionomers. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 816–825, 2000     

Fracture mechanics investigation on the PP/EPDM/ionomer ternary blends using j-integral by locus method

The fracture mechanics investigation of the polypropylene (PP)/ethylene–propylene–diene terpolymer (EPDM)/ionomer ternary blends was performed in terms of the J-integral by measuring fracture energy via the locus method. Blends were prepared in a laboratory internal mixer. The composition of PP and EPDM was fixed at a 50/50 ratio by weight. Two kinds of Poly(ethylene-co-methacrylic acid) (EMA) ionomers were used. The J-integral value at crack initiation, Jc, of the PP/EPDM/EMA ionomer ternary blends were affected by the cation types (Na⁺ or Zn²⁺) and contents (5–20 wt %) of the added EMA ionomers. The ternary blend having 5 wt % of Na-neutralized ionomer showed a higher Jc value than that of any other ternary blends. The results were discussed with regard to the fracture topology by a scanning electron microscope (SEM). © 1994 John Wiley & Sons, Inc.     

原位乳液聚合制备导电性聚苯胺/氯磺化聚乙烯复合材料及其性能

以十二烷基苯磺酸为乳化剂及掺杂剂,由二甲苯及水组成乳液,在氯磺化聚乙烯存在下,采用一步原位乳液聚合法制备了聚苯胺／氯磺化聚乙烯(PAn／CSPE)导电复合材料。研究了用熔融法(MP)或溶液法(SP)加工复合物材料的导电性及力学性能,并进行了表征。结果表明,MP法制得的复合材料在导电性及力学性能方面优于SP法制得的复合材料;当PAn质量分数为12％～18％时,MP法复合材料呈现热塑性弹性体行为,拉伸强度为6～8MPa,扯断伸长率大于400％,永久变形小于30％。当PAn质量分数小于18％时,SP法复合材料用闻甲酚二次渗杂后的导电率比原复合材料高出6个数量级,且其导电渗滤阈值由PAn质量分数22％降至3％。     

Melt flow and mechanical properties of sulfonated butyl rubber ionomers

Study of melt flow properties and mechanical properties of sulfonated butyl rubber ionomers showed that in the case of lithium ionomers addition of zinc stearate lowered obviously the melt viscosity, represented by torque value of a Brabender rheometer, and enhanced tensile strength of the ionomer up to 25% of zinc stearate, while in the case of ethylamine neutralized ionomer addition of zinc stearate lowered the melt viscosity not so obviously as in the case of lithium ionomer and slightly affected the tensile strength. Amine neutralized ionomers exhibited very low permanent sets, while the lithium ionomer showed much higher permanent set, which increased with sulfonate group and amount of zinc stearate added. Increase of neutralization degree below equivalent ratio of 1 significantly raised the melt viscosity and tensile strength. For monovalent cation ionomer, melt viscosity and tensile strength diminished with decreasing ionic potentials, but for divalent cation ionomers with increasing ionic potentials and with decreasing covalent character tensile strength decreased and melt viscosity increased. For different amine neutralized ionomers tensile strength decreased in the following orders: ethylamine > triethylamine > diethylamine; isopropylamine > ethylamine > tertiary butylamine > methylamine; ethylamine > hexylamine > dodecylamine > octadecylamine.     

Synthesis and physical properties of sulfonated syndiotactic polystyrene ionomers

Sulfonation of highly stereoregular syndiotactic polystyrene has been accomplished in 1,1,2‐trichloroethane and chloroform (60/40 v/v) mixed solvent. FTIR spectroscopy was used to confirm that the sulfonated syndiotactic polystyrene was the product of the sulfonation reactions. Sodium, potassium, zinc (II), manganese (II) and cobalt (II) salts of the sulfonated polymers exhibited behaviour indicative of strong interactions. FTIR spectroscopy and DSC data showed that the roles of the cation–anionic site interactions in alkali form and transition metal form ionomers are somewhat different. The DSC data also showed that the alkali metal cations had more pronounced effect on T_g than did the transition metal cations. In addition, the crystallization behaviour of the ionomers with a low degree of sulfonation also exhibited considerable differences in comparison with the neat syndiotactic polystyrene. The melting points (T_m) and the degree of crystallization (X_c) were significantly lowered by the presence of the sulfonic acid groups or the sulfonate metal groups. Moreover, the ionomers were more thermally stable and more hygroscopic than the unmodified polymer. © 2001 Society of Chemical Industry     

Preparation and properties of high‐performance recyclable ethylene propylene diene rubber

To obtain high‐performance recyclable ethylene propylene diene rubber (EPDM), EPDM was chemically functionalized as follows: EPDM was grafted with citraconic acid (CCA) by radical melt polymerization to produce a grafted EPDM (EPDM‐g‐CCA), and EPDM‐g‐CCA was reacted with various amino acids by melt condensation reaction to give amidated copolymers (EPDM‐g‐CCA‐2‐Am, EPDM‐g‐CCA‐7‐Am, and EPDM‐g‐CCA‐12‐Am, where the n indicates the carbon number of amino acid), and then ionomers (EPDM‐g‐CCA/n‐Am/Io) were prepared by melt reaction of EPDM‐g‐CCA/n‐Ams with Zinc oxide (ZnO)/zinc stearate (ZnSt). The mechanical properties/compression set (CS) resistance (elasticity)/recyclability of pristine EPDM, EPDM‐g‐CCA, EPDM‐g‐CCA/n‐Am, and ionomers sheet samples were compared. The tensile strength/modulus, tear strength, and elasticity of samples were mostly increased in the order of ionomers>EPDM‐g‐CCA/n‐Ams>EPDM‐g‐CCA>pristine EPDM. The properties of ionomers increased significantly with increasing the carbon number in amino acid up to seven, and then levelled off or decreased a little. The tensile strength/elasticity (compression set resistance) of recyclable ionomer (EPDM‐g‐CCA/7‐Am/Io) was found to be ～9.42/～2.31 times of pristine EPDM, respectively. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42718.     

Doped polyaniline/multiwalled carbon nanotube composites: Preparation and characterization

Polyaniline (PANI)/multiwalled carbon nanotube (MWNT) composites with a uniform tubular structure were prepared from in situ polymerization by dissolving amino‐functionalized MWNT (a‐MWNT) in aniline monomer. For this the oxidized multiwalled nanotube was functionalized with ethylenediamine, which provided ethylenediamine functional group on the MWNT surface confirmed by Fourier‐transform infrared spectra (FT‐IR). The a‐MWNT was dissolved in aniline monomer, and the in situ polymerization of aniline in the presence of these well dispersed nanotubes yielded a novel tubular composite of carbon nanotube having an ordered uniform encapsulation of doped polyaniline. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) showed that the nanotubes were coated with a PANI layer. The thermal stability and electrical conductivity of the PANI /MWNTs composites were characterized by thermogravimetric analysis (TGA) and conventional four‐probe method respectively. Compared with pure PANI, the electrical conductivity and the decomposition temperature of the MWNTs/PANI composites increased with the enhancement of MWNT content in PANI matrix. POLYM. COMPOS., 34:1119–1125, 2013. © 2013 Society of Plastics Engineers     

23Na-NMR of solid state ionomers: lineshape,shift, and hydration effects

Summary ²³Na-NMR spectra at 52.9 MHz have been obtained for a series of sodium sulfonate and carboxylate model compounds and for solid poly(styrene-co-styrene sulfonate) and poly(ethylene-co-methacrylic acid). Spectra of the model compounds show spin-rate independent features resembling pure quadrupolar lineshapes, but with anomalies. ²³Na-NMR spectra of the dried ionomers are featureless and much broader than those of the models and are shifted 30–40 ppm upfield from NaCl. The sulfonated ionomer spectrum changes to a narrow line at 0 ppm upon exposure to 45% humidity at 20°C for 12 hours. The carboxylic ionomer shows no change on room temperature air exposure but 12 hours at 95°C in watersaturated air changes the spectrum markedly with some evidence for exchange among water and carboxyl groups. This type of experiment with a range of acid and Na content under rigidly controlled conditions should help elucidate the aggregation of salt groups in various ionomers.