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％。     

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     

Preparation of conductive polyaniline‐sulfonated EPDM ionomer composites from in situ emulsion polymerization and study of their properties

The composites of polyaniline (PAn) and zinc sulfonated ethylene–propylene–diene rubber (EPDM) ionomer were made by polymerization of aniline in the presence of the ionomer by using a direct, one‐step in situ emulsion polymerization technique. The ionomers were prepared by sulfonation of EPDM rubber with acetyl sulfate in petroleum ether, followed by neutralization with zinc acetate solution. The ionomers with sulfonate contents of 10, 24, and 42 mmol SO₃H/100 g were used for preparation of PAn/ionomer composites. The in situ polymerization of aniline was carried out in an emulsion comprising water and xylene containing the ionomer in the presence of dodecyl benzene sulfonic acid, acting as both a surfactant and a dopant for PAn. The composite was characterized by IR and WAXD. The composite obtained can be processed by melt method. The conductivity of the composite with lower sulfonate content was higher than that with higher sulfonate content. Conductivity of the composites exhibits a percolation threshold at about 13 wt % PAn. When the sulfonated content is 10 or 24 mmol SO₃H/100 g and PAn content is 4–10 wt %, the composites behave as a thermoplastic elastomers with high ultimate elongation and low permanent set. The conductivity of the composite after secondary doping with m‐cresol is higher than the composite before secondary doping by about one order. Addition of zinc stearate as an ionic plasticizer lowers both the conductivity and the mechanical strength of the composites. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 2211–2217, 2004     

导电聚苯胺/聚乙烯醇复合乳液的制备研究

以聚乙烯醇为树脂基体 ,通过乳液氧化聚合同步搀杂有机酸 ,研究了聚苯胺 /聚乙烯醇复合乳液的制备。结果表明 ,过硫酸铵的用量对聚苯胺的产率影响较大 ,当氧化剂 /苯胺的摩尔比达到 2时 ,产率为95% ,高于溶液法的原料比例。十二烷基苯磺酸和聚乙烯醇 (88%醇解度 )对聚苯胺乳胶的粒径亦有影响。在聚苯胺 /聚乙烯醇复合膜中 ,当聚苯胺含量超过 2 0 %后 ,电导率趋向稳定 ,可达 2 .3 s/ cm     

乳液聚合法制备聚苯胺/聚乙烯醇电致变色材料

以十二烷基苯磺酸(DBSA)为掺杂剂,在非有机溶剂的两相体系中以聚乙烯醇(PVA)为成膜助剂,采用现场乳液聚合法合成了可直接用于制备电致变色膜的聚苯胺(PAn)/PVA乳液。研究了PVA含量、苯胺(An)与DBSA的量比、氧化剂过硫酸铵(APS)与An的量比及反应温度对膜的电致变色性、导电性的影响。实验结果表明:在w(PVA)=4 3%、n(An)∶n(DBSA)∶n(APS)=0 86∶1∶0 86、反应温度为8℃时,所制得的PAn/PVA乳液可直接制成具有良好电致变色性的自支撑膜(电致变色响应时间小于0 5s,电导率可达2 69×10-4S/m)。     

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.     

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     

In situ fast polymerization of graphene nanosheets‐filled poly(methyl methacrylate) nanocomposites

A series of graphene nanosheets‐filled poly(methyl methacrylate) nanocomposites (GNS/PMMA) is successfully prepared by an in situ fast polymerization method with graphene weight fractions from 0.1 to 2.0 wt %. In situ polymerization is effective in well dispersing of GNS in matrixes and suitable for both low and high content of GNS. The synthesis processes of polymer composites could be simplified and fast by using industrial grade graphene. The GNS fillers are found to disperse homogeneously in the PMMA matrix. The maximum electrical conductivity of the composites achieves 0.57 S m^?1, with an extremely low percolation threshold of 0.3 wt %. The electrical conductivities are further predicted by percolation theory and found to agree well with the experimental results. The results indicate that the microstructures, thermal, electrical, and mechanical properties of PMMA polymer are significantly improved by adding a low amount of graphene nanosheets. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43423.     

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.     

Synthesis and characterization of organo‐attapulgite/polyaniline‐dodecylbenzenesulfonic acid based on emulsion polymerization method

Organo‐attapulgite (OAT) was obtained by pretreating attapulgite (AT) with hexadecyltrimethyl ammonium bromide (HDTMABr) and dodecylbenzenesulfonic acid doped polyaniline (PAn‐DBSA) (OAT/PAn‐DBSA) was synthesized by emulsion polymerization at different OAT weight ratios. The perhaps polymerization procedure was supposed. The chemical structure and electronic absorption of the composites was confirmed by FTIR and UV–Vis spectroscopy, respectively. According to the X‐ray diffraction (XRD) results, it can be concluded that HDTMABr and PAn‐DBSA was just adsorbed on the surface of AT during the cation‐exchange process and OAT respectively without destroying the crystalline structure of AT or OAT. The composites showed a higher thermal stability than pure PAn‐DBSA by introduction of OAT into this polymerization system by using TGA analysis. Morphologies of the samples were confirmed by TEM and it showed that OAT was dispersed well in organic solvent after AT was pretreated with HDTMABr. The morphologies of OAT/PAn‐DBSA also supported the perhaps formation procedure we hypothesized. The electrical conductivity of the composite decreased with increasing the feed weight ratios of OAT in this polymerization system. POLYM. COMPOS., 2008 © 2007 Society of Plastics Engineers     

A novel soluble PANI/TPU composite doped with inorganic and organic compound acid

A series of novel soluble and thermoplastic polyurethane/polyaniline (TPU/PANI) composites doped with a compound acid, which was composed of an organic acid (p‐toluene sulfonic acid) and an inorganic acid (phosphoric acid), were successfully prepared by in situ polymerization. The effect of aniline (ANI) content, ratio of organic acid/inorganic acid, and different preparation methods on the conductivity of the TPU/PANI composites were investigated by using conductivity measurement. Lithium bisoxalato borate (LiBOB) was added to the prepared in situ TPU/PANI to coordinate with the ether oxygen groups originating from the soft molecular chains of TPU, and thus the conductivity of the composites was further enhanced. The molecular structure, thermal properties, and morphology of the TPU/PANI composites were studied by UV–visible spectroscopy, differential scanning calorimetry, and scanning electron microscopy, respectively. The results show that the in situ TPU/PANI composites doped with the compound acid can be easily dissolved in normal solvents such as dimethylformamide (DMF) and 1,4‐dioxane. The conductivity of the TPU/PANI composites increases with the increase of the ANI content, in the ANI content range of 0–20 wt %; however, the conductivity of the composites reduces with further increment of ANI content. The conductivity of the TPU/PANI composites prepared by in situ polymerization is about two orders of magnitude higher than that prepared by solution blending method. LiBOB can endow the in situ TPU/PANI composites with an ionic conductivity. The dependence of the conductivity on temperature is in good accordance with the Arrhenius equation in the temperature range of 20–80°C. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Development of electrical conductivity with minimum possible percolation threshold in multi-wall carbon nanotube/polystyrene composites

A method is reported that involves the bulk polymerization of styrene monomer in the presence of multi-wall carbon nanotubes (MWCNTs) and polystyrene (PS) beads, for the preparation of MWCNT/PS conducting composites with a significantly lower (0.08 wt.% MWCNT) percolation threshold than previously reported. Thus, the conductivities of 7.62 × 10⁻⁵ and 1.48 × 10⁻³ S cm⁻¹ were achieved in the MWCNT/PS composites through homogeneous dispersion of 0.08 and 0.26 wt.% CNTs, respectively in the in situ polymerized PS region by using 70 wt.% PS beads during the polymerization. The extent of dispersion and location of the MWCNTs in the PS matrix has been investigated with a scanning and transmission electron microscopy. The conductivity of the composites was increased with increasing wt.% of the PS beads at a constant CNT loading, indicating the formation of a more continuous network structure of the CNTs in PS matrix.     

Microstructural behaviors of polyaniline/CB Composites by SAXS

Polyaniline doped with dodecylbenzene sulfonic acid and conductive carbon black (PAn.DBSA/CB) hybrid materials have been prepared by in situ polymerization. The electrical resistivity of the PAn/CB was measured as a function of CB. The minimum resistivity was noticed for the composites with 25 wt % of CB as compared to other systems. Small angle x‐ray diffraction data was used to characterize the molecular arrangements of these composites. The refinement parameters such as periodicity (L), phase lengths (<Y> and <Z>), phase ratio (<Y>/<Z>), and probability distribution of phases [γ_Z (crystalline), γ_Y (amorphous)] for PAn, CB, and PAn/CB composites have been measured by SAXS data. It was observed that there is decrease in the crystallinity with increase in CB content in the composites. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Preparation of aqueous polyaniline dispersions by micellar‐aided polymerization

Polyaniline (PAn) dispersed in water was prepared with sodium dodecylsulfonate (SDS) as a surfactant with varying concentrations of aniline and HCl and molar ratios of SDS/aniline. The PAn dispersion was homogeneous and stable, and its pH value could be adjusted. The conductivity of PAn powder, precipitated from this dispersion, was as high as 20 S/cm. The transmission electron microscopy morphology of PAn assembled in the dispersion was particle‐like, fiber‐like, or coil‐like, depending on the initial concentration of SDS and aniline. The polymerization of aniline was accelerated by SDS, which was confirmed by open‐circuit potential measurement during the polymerization process. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1550–1555, 2003     

Polyaniline-silver composites prepared by the oxidation of aniline with mixed oxidants, silver nitrate and ammonium peroxydisulfate: The control of silver content

Aniline was oxidized with mixtures of two oxidants, ammonium peroxydisulfate and silver nitrate, to give polyaniline-silver composites with variable content of silver in the composites. The presence of peroxydisulfate has a marked accelerating effect on the oxidation of aniline with silver nitrate. Oxidations in 1 M methanesulfonic acid produced composites in high yield. The molecular structure of the polyaniline was confirmed by UV-visible and FTIR spectra, and the polymeric character was established by gel-permeation chromatography. The content of silver varied between 0 and 70 wt.%. The silver nanoparticles were smaller than 100 nm. The conductivity of the composites was of the order of units S cm⁻¹. Only at high silver nitrate contents in the reaction mixture, the conductivity of products exceeded 100 S cm⁻¹. The conductivity of the composites sometimes increased after deprotonation of the polyaniline salt to a non-conducting base. Such conductivity behaviour is discussed in terms of the percolation model.     

Electromagnetic radiation shielding by composites of conducting polymers and wood

Polyaniline or polypyrrole composites with fir or oak wood have been prepared by in situ polymerization of the corresponding monomers in an aqueous suspension of wood sawdust. The percolation threshold of compressed coated particles is located below 5 wt % of the conducting component and, above this limit, the conductivity of most composites was higher than 10^?3 S cm^?1. The conductivity of composites containing ca 30 wt % of conducting polymer was of the order of 10^?1 S cm^?1, an order of magnitude lower than that of the corresponding homopolymers, polyaniline and polypyrrole. The conductivity stability has been tested at 175°C. The polypyrrole‐based composites generally lasted for a longer time than pyrrole homopolymers, also on account of the improved mechanical integrity of the samples provided by the presence of wood. The reverse order was found with polyaniline composites. The dielectric properties of the composites were determined in the range of 100 MHz–3 GHz, indicating that thick layers of composite material, ～ 100 mm, are needed for the screening of the electromagnetic radiation below ?10 dB level in this frequency range. Nevertheless, considering the potential production cost of composites and their low weight, such composite materials could be of practical interest in the shielding of electromagnetic interference. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 95: 807–814, 2005     

Electromagnetic interference shielding of graphite/acrylonitrile butadiene styrene composites

Dispersion of graphite within the acrylonitrile butadiene styrene matrix demonstrates enhanced electromagnetic interference shielding of composites through the use of tumble mixing technique. A shielding effectiveness of 60 dB with 15 wt % of graphite has been achieved. D shore hardness data revealed a little decrease in hardness of composites with rise in graphite content. DC conductivity measurements revealed a fairly low percolation threshold at 3 wt % of graphite. The conductivity exhibited by 15 wt % composite is 1.66 × 10⁻¹ S/cm. These composites are fit for use as an effective and convenient EMI shielding material because of easy processing, better hardness, light weight, and, reasonable shielding efficiency. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Reduced percolation concentration in polypropylene/expanded graphite composites: Effect of viscosity and polypyrrole

With the goal to obtain material combining electrical and thermal conductivity at low filler loadings, composites based on polypropylenes (PP) and expanded graphite (EG) have been prepared. The effects of matrix viscosity and of coating the EG particles with polypyrrole (PPy, EG/PPy = 37.5/62.5 by weight) on the EG dispersibility and formation of percolation structures have been analyzed. When increasing the EG amount from 6 to 8 wt %, the electrical conductivity of PP/EG composites increased by 7–9 orders of magnitude, independent of matrix viscosity. When EG‐PPy is added, percolation was observed between 8 and 12 wt % EG‐PPy (3 and 4.5 wt % EG) in case of PP with higher viscosity and 6 wt % EG (2.25 wt % EG) in case of PP with lower viscosity, exhibiting a strong synergistic effect of EG and PPy in the latter case. In contrast, PPy does not contribute to reduction of thermal percolation concentration. Thermal percolation is observed at 8 wt % EG in PP/EG composites, but no percolation was found in PP/EG‐PPy composites with EG‐PPy contents of up to 20 wt %, corresponding to 7.5 wt % EG. Analyzing the melt rheology it becomes clear that the contribution of PPy to the formation of a filler network is strongly dependent on the matrix viscosity. The comparison of thermal, electrical and rheological percolation reveals that PPy participates in electron transport reducing the electrical percolation but not to heat transport. Overall, we found a good correlation between electrical, thermal, and melt rheological percolation concentrations. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41994.     

Enhanced positive temperature coefficient in amorphous PS/CSPE-MWCNT composites with low percolation threshold

In this work, amorphous polystyrene/chlorosulfonated polyethylene composites doped with multiwalled carbon nanotubes (PS/CSPE-MWCNT) were constructed by in situ polymerization to form semi-interpenetrating networks. The MWCNTs showed excellent dispersion and selective location in the PS regions. High electrical conductivity and low percolation threshold (0.89 wt %) for the composites were achieved. An enhanced positive temperature coefficient (PTC) behavior for amorphous PS/CSPE-MWCNT composites was first reported, nearly without a negative temperature coefficient (NTC) effect when the conductive fillers were beyond the percolation threshold, similar to those of crystalline polymer composites. Moreover, a PTC intensity of more than five orders of magnitude and excellent repeatability of the PTC effect were achieved. This study offers new insight into the development of novel PTC materials with low percolation threshold. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47053.     

聚苯胺/纳米石墨复合材料的原位制备与导电性能研究

采用原位聚合法制备了聚苯胺/纳米石墨微片（PANI/NanoG）导电复合材料。结果表明,NanoG的直径约为1~20 μm,厚度为30~90 nm,径厚比为300~500;PANI均匀覆盖在NanoG表面;当NanoG体积含量为2.30 %时,复合材料电导率达到5.16 S/cm,其渗滤阈值达到2.30 %,NanoG的高比表面积及在PANI中的分散造就了复合材料良好的导电性能。