An easy one-step electrosynthesis of graphene/polyaniline composites and electrochemical capacitor

An easy electrochemical technique is proposed to prepare electrochemically reduced graphene oxide (ERGO)/polyaniline (PANI) composites in a single step. The technique uses a two-electrode cell in which a separator soaked with an acid solution is sandwiched between graphene oxide (GO)/aniline films deposited on conductive substrates and an alternating voltage was applied to the electrodes. Successful preparations of ERGO/PANI composites were evidenced by characterizations due to UV–vis-NIR, FT-IR, XPS, XRD, and SEM measurements with free-standing films of ERGO/PANI obtained easily by disassembling the two-electrode cells. The ERGO/PANI films exhibited a high mechanical stability, flexibility, and conductivity (68 S cm⁻¹ for the composite film containing 80% ERGO) with nanostructured PANI particles (smaller than 20 nm) embedded homogeneously between the ERGO layers. The two-electrode cells acted as electrochemical capacitors (ECs) after a sufficient voltage cycling and exhibited relatively large specific capacitances (195–243 F g⁻¹ at a scan rate of 100 mV s⁻¹) with an excellent cycle life (retention of 83% capacitance after 20,000 charge–discharge cycles). Influences of the GO/aniline ratio, the sort of electrolytes, and the weight of the composite on the energy storage characteristics of ECs comprising the ERGO/PANI composites were also studied.     

聚苯胺/磺化EPDM锌离聚体导电复合物的制备与性能

在十二烷基苯磺酸存在下，用原位乳液聚合技术聚合苯胺，制得了聚苯胺和磺化乙丙橡胶（EPDM）锌离聚体复合物，EPDM锌离聚体由EPDM磺化及中和制得。用磺化度分别为0.10,0.24,0.40mmol/g的EPDM锌离聚体作为基质制备出各自的复合物，复合物可以熔融热塑加工，其导电率呈现的渗滤阈值为13%，在聚苯胺质量分数相同的情况下，磺化度小的复合物的电导率高于磺化度大的复合物。当磺化度为0.10mmol/g、聚苯胺质量分数为6%～11%和磺化度为0.24mmol/g、聚苯胺质量分数为2%～11%时，复合物表现出热塑性弹性体的行为，扯断伸长率达200%～500%，永久变形小于40%，用间甲酚进行二次掺杂后复合物的电导率有所提高，加入硬脂酸锌会降低复合物的电导率及力学性能。     

A study of polyurethane ionomer dispersant

Anionic polyurethane ionomers as the dispersant in water‐soluble acrylic baked paint were successfully synthesized at our lab and these ionomer structures have been proven by infrared spectra. In aqueous solution, the surface tension for polyurethane ionomer molecules with different ionics was found to increase with increasing the concentration of ionics, as a result of the hydrophobics of ionomer molecules adsorbed at the air–water interface becoming even more ordered. It was also found that the viscosity is higher for polyurethane ionomer with L ‐2,5‐diaminovaleric acid hydrochloride than for polyurethane ionomer with sodium 4,4‐dihydroxy‐l‐butane sulfonate (DS200) or with dimethylol propionic acid (DMPA) in water. For the wettability and dispersion of titanium dioxide pigment present in water‐soluble acrylic baked paint, the polyurethane ionomer molecules with respective sodium 4,4‐dihydroxy‐L ‐butane sulfonate, DMPA, DS200 containing 3% 1,3‐propane sultone (ES200) and DMPA containing 3% ES200 are considered to be better dispersants. The titanium dioxide pigment was found to become finer, as the agitation time and the ionic concentration of anionic polyurethane ionomer were increased. In addition, the system with DS200 or dimethylol propionic acid will make the dispersion of titanium dioxide pigment stable in water‐soluble acrylic paint. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 103–111, 2005     

导电聚氨酯泡沫的制备

以聚氨酯软泡为基体制备了炭黑/聚氨酯泡沫复合材料,实验以热塑性聚氨酯(TPU)粉末为黏结剂,采用浸渍法制备导电聚氨酯泡沫材料,研究了溶剂、导电炭黑用量及聚氨酯泡沫泡孔对所制备复合材料电学及力学性能的影响。实验表明,丙酮为溶剂、m(炭黑):m(TPU)为0.36时使用低密度泡沫制备出的复合材料具有更优异的电学和物理性能。     

Electrical conductivity and EMI shielding effectiveness of polyurethane foam–conductive filler composites

The morphological, electrical, and thermal properties of polyurethane foam (PUF)/single conductive filler composites and PUF/hybrid conductive filler composites were investigated. For the PUF/single conductive filler composites, the PUF/nickel‐coated carbon fiber (NCCF) composite showed higher electrical conductivity and electromagnetic interference shielding effectiveness (EMI SE) than did the PUF/multiwall carbon nanotube (MWCNT) and PUF/graphite composites; therefore, NCCF is the most effective filler among those tested in this study. For the PUF/hybrid conductive fillers PUF/NCCF (3.0 php)/MWCNT (3.0 php) composites, the values of electrical conductivity and EMI SE were determined to be 0.171 S/cm and 24.7 dB (decibel), respectively, which were the highest among the fillers investigated in this study. NCCF and MWCNT were the most effective primary and secondary fillers, and they had a synergistic effect on the electrical conductivity and EMI SE of the PUF/NCCF/MWCNT composites. From the results of thermal conductivity and cell size of the PUF/conductive filler composites, it is suggested that a reduction in cell size lowers the thermal conductivity of the PUF/conductive filler composites. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44373.     

3D打印炭黑/水性聚氨酯导电复合材料的制备及性能

采用硅烷偶联剂KH550对炭黑（CB）进行共价键功能化改性,并通过FTIR、DLS和SEM对改性前后的炭黑进行考察。结果表明经过KH550改性得到的炭黑,粒径约为620nm,且分散均匀。通过溶液共混法和流延浇铸法制备了CB/WPU与KH550/CB/WPU导电复合材料。研究对比发现,由于KH550/CB在WPU基体中分散性更好,使导电粒子之间接触更加紧密。当添加量为3%时,其电导率为1.79×10-3 S/m,较CB/WPU复合材料增加了10倍;力学测试显示含量为2%时,其拉伸强度较CB/WPU复合材料增加了175%。并在此基础上利用直写式3D打印,探讨不同的填充图案和填充率对KH550/CB/WPU复合材料导电性能的影响。结果显示选择线型填充、填充率为80%时,导电性能较好,其电导率达到2.66×10-3 S/m。     

A study of colored siloxane-based polyurethane ionomer

The reaction of dye with toluene diisocyanate and dimethyldichlorosilane in the presence of other additives to form a colored siloxane-based polyurethane (PU) ionomer has been proven to occur by infrared spectra. In aqueous solution, the number-average particle size for the colored siloxane-based PU ionomer was found to increase with an increase in the NCO-to-OH ratio, dye concentration, and dimethyldichlorosilane concentration, as a result of increased free volume of the ionomer molecules. It is worthy to note that the amount of air diffusing into the film cast from colored siloxane-based PU ionomer was found to increase with an increase in the concentration of dimethyldichlorosilane instead of raising the ratio of NCO to OH or the concentration of dye, as a result of the formation of more porosities. In addition, the tensile strength of this film will be strengthened by raising the NCO/OH ratio or the concentration of dimethyldichlorosilane, whereas the elongation, on the other hand, can be substantially increased with increasing the concentration of dye instead of increasing the concentration of dimethyldichlorosilane for use in the PU ionomer system. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 2097–2105, 1998     

Poly(vinylidene fluoride)/thermoplastic polyurethane flexible and 3D printable conductive composites

This work focus on the development of polymeric blends to produce multifunctional materials for 3D printing with enhanced electrical and mechanical properties. In this context, flexible and highly conductive materials comprising poly(vinylidene fluoride)/thermoplastic polyurethane (PVDF/TPU) filled with carbon black-polypyrrole (CB-PPy) were prepared by compression molding, filament extrusion and fused filament fabrication. In order to achieve an optimal compromise between electrical conductivity, mechanical properties and printability, blends composition was optimized and different CB-PPy content were added. Overall, the electrical conductivities of PVDF/TPU 50/50 vol% co-continuous blend were higher than those found for PVDF/TPU 50/50 wt% (i.e., 38/62 vol%) composites at same filler content. PVDF/TPU/CB-PPy 3D printed samples with 6.77 vol% filler fraction presented electrical conductivity of 4.14 S m⁻¹ and elastic modulus, elongation at break and maximum tensile stress of 0.43 GPa, 10.3% and 10.0 MPa, respectively. These results highlight that PVDF/TPU/CB-PPy composites are promising materials for technological applications.     

Water vapor‐permeable polyurethane ionomer

The reaction of toluene diisocyanate with 2,2,3,3‐tetrafluoro‐1‐propanol (fluoro compound) or 3‐glycidoxypropyl trimethoxysilane(siloxane compound) and other additives to form the structure of the fluoro‐based or siloxane‐based polyurethane (PU) ionomer has been proven by infrared spectra. Experimental results indicated that the amount of water vapor permeability of the film made by fluoro‐based or siloxane‐based PU ionomer appeared to gradually increase with increasing concentration of the siloxane compound or fluoro compound, as a result of the formation of more porosities. Our experimental results also showed that the water vapor absorption was seen to be larger for the film made by siloxane‐based PU ionomer film than for the film made by fluoro‐based PU ionomer film, as a result of increased hydrophilic groups attached to the backbone of the PU ionomer molecule. For the film prepared by siloxane‐based PU ionomer, both tensile strength and elongation appeared to increase with an increase in the concentration of siloxane compound. This may be the result of the intermolecular interaction between siloxane‐based PU ionomer molecules themselves, thus enhancing the crosslinking capability of the ionomer molecules. On the other hand, both tensile strength and elongation for the film prepared by fluoro‐based PU ionomer decreased with increasing concentration of the fluoro compound, as a result of intramolecular interaction greatly reducing the crosslinking capability of the ionomer molecules. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3767–3773, 2006     

新颖离子导电型聚氨酯弹性体

以低聚二氧戊环磺酸盐(SPDXL)为离子源和增塑剂,聚己二酸乙二醇酯聚氨酯弹性体(EGPU)为基质,设计了一种新颖的正离子导电型聚氨酯弹性体,并对其结构、形态及性能进行了研究。结果表明,通过选取适当平均相对分子质量的磺化低聚醚以及通过控制磺化低聚醚的质量分数,可以优化聚氨酯固体电解质体系的离子导电性能。对于EGPU/SPDXL固体电解质体系,采用SPDXL800的样品具有较高的离子导电性能,其室温离子电导率均达到10-6S/cm以上。     

氧化铝/环氧树脂/聚氨酯导热复合材料的制备及表征

采用硅烷偶联剂KH550对氧化铝表面进行改性,并以改性氧化铝为导热填料,以环氧树脂为基体树脂,自制的聚氨酯预聚体为柔性改性剂,制备了氧化铝/环氧树脂/聚氨酯导热复合材料。采用红外光谱对KH550改性氧化铝的结构进行了表征,探讨了影响复合材料热导率的主要因素,研究了改性氧化铝用量对复合材料力学性能的影响,并利用扫描电镜对复合材料的微观结构进行了观察。结果表明,KH550已通过化学键接枝在氧化铝表面。随着KH550改性氧化铝用量的增加,复合材料的拉伸强度逐渐增大,而导热率和断裂伸长率呈现先上升后下降的趋势。当改性氧化铝的用量为150 phr时,复合材料的导热率达到最大值0.66 W/(m·K),拉伸强度和断裂伸长率分别为37.2 MPa和1.62%。随着m(PUA)/m(EP)的增大,复合材料的导热率相应下降,适宜的m(PUA)/m(EP)为15/85。     

导电聚氨酯泡沫材料研究进展

从使用不同导电填料（炭黑、碳纳米管、石墨、金属、有机填料等）制备导电聚氨酯泡沫（PUF）材料的角度进行分析,总结了添加不同导电填料的复合泡沫制备方法以及对泡沫材料性能的影响,并论述了导电PUF材料在压阻材料、吸波材料、电磁屏蔽材料以及电极材料等领域的应用。分析表明,通过添加导电填料,可以改善PUF的静电现象,提高防静电、导电等性能并拓宽PUF材料的应用领域。     

Nylon fiber reinforcement for polyurethane composites

The potential of a nylon 6 fiber was evaluated for composite applications involving rigid polyurethane systems. A study showed that the use of COMPET N, a nylon 6 based fiber surface treated to enhance wetout and adhesion, in an ISP polyurethane system results in composites with higher impact values and lower weight than those reinforced with glass fiber. A 2 percent loading of COMPET N matt increased impact values by more than 300 percent over an unreinforced control while a 3 percent loading of glass matt resulted in increases of less than 100 percent. A drop impact test showed COMPET N fabric reinforced composites to absorb twice as much energy as an unreinforced and glass reinforced composite without major damage. These advantages have also been observed in COMPET N/Glass hybrids, in which layer orientation can be used to produce composites with specific properties. Cut fiber reinforced composites were found to exhibit similar properties as fabric reinforced ones resulting in the commercialization of a canoe end cap containing cut nylon fiber. Additional property benefits such as improved impact fatigue and decreased stress cracking have also been observed in nylon 6 reinforced composites resulting in the consideration of these materials for a wide range of applications.     

Silicone membranes to inhibit water uptake into thermoset polyurethane shape‐memory polymer conductive composites

Electroactive shape memory polymer (SMP) composites capable of shape actuation via resistive heating are of interest for various biomedical applications. However, water uptake into SMPs will produce a depression of the glass transition temperature (T_g) resulting in shape recovery in vivo. While water actuated shape recovery may be useful, it is foreseen to be undesirable during early periods of surgical placement into the body. Silicone membranes have been previously reported to prevent release of conductive filler from an electroactive polymer composite in vivo. In this study, a silicone membrane was used to inhibit water uptake into a thermoset SMP composite containing conductive filler. Thermoset polyurethane SMPs were loaded with either 5 wt % carbon black or 5 wt % carbon nanotubes, and subsequently coated with either an Al₂O₃‐ or silica‐filled silicone membrane. It was observed that the silicone membranes, particularly the silica‐filled membrane, reduced the rate of water absorption (37°C) and subsequent T_g depression versus uncoated composites. In turn, this led to a reduction in the rate of recovery of the permanent shape when exposed to water at 37°C. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41226.     

Thermally conductive polymer composites for electronic packaging

Polyurethane composites filled with alumina or carbon fibers were prepared to study the thermal conductivities and dielectric properties of polymer composites under humid environments. The thermal conductivities of these polymer composites in relation to filler concentrations and filler sizes were investigated and it was found that the thermal conductivities can increase up to 50 times that of pure polyurethane. The results were analyzed using Agari's model to explain the intrinsic reasons to affect the thermal conductivities of composites. The dielectric loss of these polymer composites were also measured to estimate the influence of moisture under various humid environments. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65: 2733–2738, 1997     

Electrically conductive composites of polyurethane derived from castor oil with polypyrrole‐coated peach palm fibers

Electrically conducting fibers were prepared through in situ oxidative polymerization of pyrrole (Py) in the presence of peach palm fibers (PPF) using iron (III) chloride hexahydrate (FeCl₃·6H₂O) as oxidant. The polypyrrole (PPy) coated PPF displayed a PPy layer on the fibers surface, which was responsible for an electrical conductivity of (2.2 ± 0.3) × 10⁻¹ S cm⁻¹, similar to the neat PPy. Electrically conductive composites were prepared by dispersing various amounts of PPy‐coated PPF in a polyurethane matrix derived from castor oil. The polyurethane/PPy‐coated PPF composites (PU/PPF–PPy) exhibited an electrical conductivity higher than PU/PPy blends with similar filler content. This behavior is attributed to the higher aspect ratio of PPF–PPy when compared with PPy particles, inducing a denser conductive network formation in the PU matrix. Electromagnetic interference shielding effectiveness (EMI SE) value in the X‐band (8.2–12.4 GHz) found for PU/PPF–PPy composites containing 25 wt% of PPF–PPy were in the range −12 dB, which corresponds to 93.2% of attenuation, indicating that these composites are promising candidates for EMI shielding applications. POLYM. COMPOS., 38:2146–2155, 2017. © 2015 Society of Plastics Engineers     

Waterborne polyurethane and modified polyurethane acrylate composites

Abstract

Waterborne polyurethane (PU) and a series of PU acrylate (PUA) composite dispersions were synthesised from isophorone diisocyanate, polyester polyols, dimethylol propionic acid, hydroxyethyl methyl acrylate, butyl acrylate and methyl acrylate. Fourier transform infrared, ultraviolet visible and differential scanning calorimetry were used to demonstrate structures, optical transparency and thermal stabilities of PU and PUA. The PUA sample had lower glass transition temperature of hard segment and higher decomposition temperature than the PU sample. Performances of the dispersion and film were studied by means of apparent viscidity, particle size and particle size distribution index, surface tension and mechanical property. The results indicated that the solvent resistance and mechanical property of PUA film were improved compared with the pure PU film. The obtained stable PUA composite samples have excellent integrated properties and have a great potential application in meeting the highly diversified demands in modern technologies, such as coatings, leather finishing, adhesives, sealants, rubbers, plastic coatings and wood finishes.     

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     

Lightweight and thermally conductive thermoplastic polyurethane/hollow glass bead/boron nitride composites with flame retardancy

Polymeric composites with low density and high thermal conductivity (TC) are greatly demanded in some specific applications such as aeronautics, astronautics, and deep-sea exploration. It is a great challenge to obtain lightweight and thermally conductive polymer composites because the heat fillers have high density (>2 g/cm³) Herein, lightweight and thermally conductive thermoplastic polyurethane/hollow glass bead/boron nitride composites (TPU/HGB/BN) were prepared with the construction of a 3D BN network under the assistance of ultralightweight HGB by a solution-mixing and hot-pressing method. A 3D BN heat network has been constructed in the TPU matrix due to the alignment of the BN platelets along with the HGB microspheres during hot-pressing, which leads to a higher TC (5.34 W/mK) of the TPU/HGB/BN composites with a low density of 1.23 g/cm³, which is close to the density of pure TPU (1.20 g/cm³). In addition, the TPU/HGB/BN composites show good thermal stability with TC losses of 4.24% and 2.22%, respectively, even after treated for 50 hot-cold cycles and heated at 80 °C for 50 h. Moreover, the limiting oxygen index (LOI) of the TPU/HGB/BN composites is 51%, and they can extinguish in 8 s after ignition and exhibit enhanced flame retardancy. This work presents a simple method to design and prepare lightweight, flame retardant and thermally conductive composite materials, which can be used as lightweight thermal management materials.     

Hybrid electrically conductive polyaniline/polyurethane foams

Electrically conductive polyaniline/polyurethane foams were prepared. The DC conductivity of the composite prepared at pH = 0.505 is about 0.9 S/cm. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 893–897, 2001