Conductive Blends Research Articles

Self-healing, stretchable and recyclable polyurethane-PEDOT:PSS conductive blends.

Future electronics call for materials with mechanical toughness, flexibility, and stretchability. Moreover, self-healing and recyclability are highly desirable to mitigate the escalating environmental threat of electronic waste (e-waste). Herein, we report a stretchable, self-healing, and recyclable material based on a mixture of the conductive polymer poly(3,4-ethylenedioxythiophene) doped with polystyrene sulfonate (PEDOT:PSS) with a custom-designed polyurethane (PU) and polyethylene glycol (PEG). This material showed excellent elongation at brake (∼350%), high toughness (∼24.6 MJ m-3), moderate electrical conductivity (∼10 S cm-1), and outstanding mechanical and electrical healing efficiencies. In addition, it demonstrated exceptional recyclability with no significant loss in the mechanical and electrical properties after being recycled 20 times. Based on these properties, as a proof of principle for sustainable electronic devices, we demonstrated that electrocardiogram (ECG) electrodes and pressure sensors based on this material could be recycled without significant performance loss. The development of multifunctional electronic materials that are self-healing and fully recyclable is a promising step toward sustainable electronics, offering a potential solution to the e-waste challenge.

Preparation and characterization of conductive blends of polyaniline with polyphenol red

Polymers are widely employed in biomedical applications, pharmaceutical product formulation, and drug delivery systems. Since every polymer has its own distinct properties, polymer blends will have novel chemical and physical properties. Functionally, the purpose of blending polymers is to improve, customize, or maximize material performance. In this study, polyaniline and polyphenol red polymer mixtures were prepared electrochemically and characterized with XPS imaging and SEM whether their distribution was homogeneous. The mixture of aniline and phenol red was deposited glassy carbon electrode (GCE) surface using the cyclic voltammetry technique in the potential range of -0.80 V to 2.00 V with 50 mV/s scan rate for 25 cycles. The phase separation of the two polymers was demonstrated by a combination of spectroscopic imaging and microscopy. For this purpose, the X-ray spot size and step number were set to 50μm. 1 x 1 mm2 area scan of the polymer mixtures was performed, and spectra were obtained at each pixel in an array of 20 x 20 pixels. Chemical imaging was obtained by applying Principal Component Analysis (PCA) to collected XPS survey spectra. For the morphological characterization, scanning electron microscopy (SEM) was employed, and images were obtained at magnifications of 5000 x. The results obtained in the mixtures prepared with 5%, 10% and 25% were better compared to the mixture prepared with 50% polyphenol red. Since the X-ray spot size is limited, the desired image resolution could not be obtained. It was shown that XPS imaging studies could also be used for examining the distribution of different and unknown polymer mixtures together with SEM.

A mechanical, thermal and electrical properties study of novel vulcanised blends of poly(epichlorohydrin) elastomer with polyaniline dodecylbenzenesulfonate

With good mechanical and thermal properties, elastomers having appreciable electrical conductivity may potentially be developed as smart materials for applications such as strain sensors, artificial muscles or flexible biosensors. With such applications in mind, the purpose of this study was to investigate the structure-properties relationships of new vulcanised blends of a poly (epichlorohydrin) elastomer (PECH) and electrically-conducting polyaniline dodecylbenzenesulfonate salt (PAni.DBSA). PAni.DBSA, synthesised by a published method, was blended with PECH and vulcanised with a commercial sulfur cross-linking agent in an internal mixer. The morphological, mechanical, thermal and electrical properties were examined as a function of the amount of PAni.DBSA in the blends. The electrical conductivities increased with the proportion of polyaniline, showing a low percolation threshold of about 1 wt. % (1.07 vol %) PAni.DBSA (from about 10−12 to 10−10 S cm−1), and a second stage of percolation around 5 wt.%, ultimately reaching around 3 × 10−8 S cm−1. The results from microscopy and other techniques indicated that a mixture of micro- and nano-sized PAni.DBSA particles was dispersed in the elastomer matrix at compositions above 5 wt. % PAni.DBSA. The infrared spectra of vulcanised PECH-PAni.DBSA blends showed features of the pure polymers, with some notable peak shifts due to intermolecular interactions between the constituents. Thermal properties of the conductive blends were investigated using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The thermal stabilities of the blends were strongly dependent on the ratio of PAni.DBSA to PECH, and the two components inhibited the thermal decomposition of each other. The elastomer’s glass transition temperature (Tg) was determined by thermomechanical analysis (TMA); each blend showed only one such transition, at temperatures that increased monotonically with the proportion of PAni.DBSA present, indicating a significant degree of molecular interaction between the two polymers.

Preferential localization of conductive filler in ethylene‐co‐methyl acrylate/thermoplastic polyolefin polymer blends to reduce percolation threshold and enhanced electromagnetic radiation shielding over K band region

AbstractTo minimize radiation pollution at ultra‐low filler concentrations, there is a growing interest in microwave‐absorbing materials based on polymer blends composites. Herein, ethylene‐co‐methyl acrylate (EMA)/thermoplastic polyolefin (TPO) blend composites were prepared by employing solution mixing utilizing conductive Vulcan XC 72 carbon black (VCB) as nanofiller. The work focused on the reduction of electrical percolation and outstanding electromagnetic interference (EMI) shielding performance in low loading caused by the preferential distribution of carbon particles in one phase (ethylene‐co‐methyl acrylate copolymer) of the co‐continuous immiscible polymer blend. The fabricated conductive blend was further tested to ensure its superiority in physic‐mechanical and thermal stability. The morphology analysis reveals that the VCB particles are selectively localized in EMA phase of the blend which facilitates the formation of compact spatial conductive network throughout the matrix for electronic hopping. High electrical conductivity is achieved in the scale 10−2 S/cm for the prepared composites with 30 wt% of carbon black loading whereas a total EMI shielding effectiveness of −29 dB and thermal conductivity of ~0.75 W/m·K are achieved for this same filler content. This study reveals that the fabricated conductive polymer nanocomposites can be effectively utilized as promising EMI shields in the future generation of stretchable and wearable electronics.

Development of polyaniline/ethylene propylene diene monomer rubber (PANI/EPDM) conductive blend by in situ polymerization technique

Development of polyaniline/ethylene propylene diene monomer rubber (PANI/EPDM) conductive blend by in situ polymerization technique

Visualization of Macrophase Separation and Transformation in Immiscible Polymer Blends

Visualization of Macrophase Separation and Transformation in Immiscible Polymer Blends

Structural and Morphological Properties of As-Deposited and Heat Treated Blended Graphene Oxide / Poly(3,4-Ethylenedioxythiophene)-Poly(Styrenesulfonate) Thin Films

In this study the as-deposited and heat treated at 423K of conductive blend graphene oxide (GO)/ poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) thin films was prepared with different PEDOT:PSS concentration (0, 0.25, 0.5, 0.75 and 1)w/w on pre-cleaned glass substrate by spin coater. The XRD analysis indicate the existence of the preffered peak (001) of GO around 2θ=8.24° which is domain in all GO/ PEDOT:PSS films characterized for GO, this result approve the good quality of the PEDOT:PSS dispersion in GO, this peak shifted to the lower 2θ with increasing PEDOT:PSS concentration and after annealing process. The scanning electron microscopy (SEM) images and atomic force microscopy (AFM) clearly show the GO flakes and go to disappear with increasing the PEDOT:PSS concentration.

Development of conductive molecularly imprinted polymers (cMIPs) for limonene to improve and interconnect QCM and chemiresistor sensing

This paper presents a straightforward method to develop a chemiresistor based sensor for the detection of the plant volatile R-(+)-limonene. By using blends of polystyrene-based molecularly imprinted polymers (MIPs) and the organic semiconductor poly3-hexylthiophene (P3HT), electrical conductivity is introduced into the highly selective MIPs, allowing their application as sensing layers in robust and economic chemiresistor devices. Polystyrene-based MIPs and conductive blends were assessed on quartz crystal microbalances (QCMs) and chemiresistors and compared to non-imprinted polymer (NIP) and pristine P3HT layers. Blending MIPs and conductive polymers led to a strong signal enhancement, both on the QCM as well as during resistive measurements, allowing for detecting R-(+)-limonene gas concentrations as low as 50 ppm. The presented results provide a simple and valuable way for potential MIP sensing improvements and the possibility for a method transfer to cheap and simple chemiresistors.

Development of Electromagnetic Shielding Material from Conductive Blends of Polyaniline/Polystyrene‐isoprene‐styrene Copolymer

AbstractThe interference of different electromagnetic waves is considered a major concern in the current era. Various materials serve as potential candidates for shielding, but polymer composites have gained attention due to their superior properties. Polymer composites of poly(styrene‐isoprene‐styrene) (SIS) and polyaniline (PANI) are prepared with the help of solvent casting technique to study electromagnetic interference shielding effectiveness. To study the properties of these blends, different techniques were utilized, including FTIR, SEM, XRD. With the help of a conductivity test, the composites have shown improvement in electrical conductivity up to 1.18 Scm−1. Electromagnetic interference shielding effectiveness was measured within the X‐band by using a vector network analyzer (VNA). The results observed showed an increase in attenuation up to 16dB upon optimum polyaniline concentration. The interaction and dispersion rate of filler is regarded as the primary aspect for enhanced properties. However, the agglomeration caused due to higher content of polyaniline resulted in decreased properties, i. e., 20 wt. % polyaniline.

Selective distribution of conductive carbonaceous inclusion in thermoplastic elastomer: A wet chemical approach of promoting dual percolation and inhibiting radiation pollution in X-band

Reinforced polymer blend is a well-practiced area of interest adopted by materials scientist throughout the world due to its tunable end properties. The present study has been fueled by developing an immiscible thermoplastic elastomeric blend (polystyrene/ethylene-co- methyl acrylate copolymer) with loading of conducting carbon black (Vulcan XC 72); an overworked conductive clustered carbon filler. The work emphasized selective dispersion of carbon particulates in one phase (ethylene-co-methyl acrylate copolymer) resulting lowering of electrical percolation and excellent EMI shielding effectiveness in low loading. The conductive blend was also cross-checked to establish their superiority in physico-mechanical, rheological behaviors and thermal stability. The microscopic analysis has implied dispersed islands of clustered carbon particles inside blend ensuing path for electronic hopping. The segregated microstructure also has been correlated to their frequency dependent conductivity, skin depth analysis and EMI shielding measurement.

Morphology development to achieve electrical conductive blends based on polylactic acid/polyolefin elastomer/graphene nanoplates

Morphology development to achieve electrical conductive blends based on polylactic acid/polyolefin elastomer/graphene nanoplates

Preparation and Characterization of Conductive blend composites of PP filled with ionic liquids treated-CNT

According to the facile melt blending method, a series of conductive blend composites based on polypropylene with the excellent electrical conductivityare prepared by Multi-walled carbon nanotube (MWCNT) and ionic liquid (IL). In light of the results of the FTIR and Raman, it was confirmed that the MWCNT was non-covalent modified by IL. The dispersion of MWCNT and the electrical conductivity of the composites are enhanced by the addition of a master-batch as a compatibilizer and IL as a modifier, respectively. With the adding of MWCNTs, the surface resistivity of the conductive blend composites was reduced by 4∼6 orders of magnitude under the same IL loading.

Flexible conductive blend of natural rubber latex with PEDOT:PSS

Natural Rubber Latex (NRL) obtained from Hevea brasiliensis is a biocompatible electrically insulating material with exceptional mechanical properties. Poly(3,4-ethylene dioxythiophene) poly(styrene sulfonate), PEDOT:PSS, on the other hand, is a biocompatible highly conductive organic material with poor flexibility. We hereby introduce a blend of NRL/PEDOT:PSS (N/P). This study involved different N/P volume ratios and temperatures of curing aiming at an optimal combination of good flexibility and conductivity. Low-temperature annealing, at 60 °C, dries and cures the blend in a few minutes and improves its tensile strength and conductivity. The blend can stretch more than 700% of its initial length and presents a good gauge factor and small resistance variation (R/R0) for ΔL/L0 of up to 100%. Among the different N/P concentrations, the membranes of an N/P ratio of 1/4 and those thermally cured have the most promising conductive flexible properties for bioelectronic applications.

Manipulating the morphology of PA6/POE blends using graphene to achieve balanced electrical and mechanical properties

We investigate the effect of graphene localization on the morphology and properties of Polyamide 6 (PA6)/Polyolefin elastomer (POE) blends. Two systems with different compositions were studied: (i) 60/40 (a composition near phase inversion) and (ii) 80/20 (a highly asymmetric composition). In this study, we demonstrate that the migration behavior of graphene is strongly dependent on its dispersion state, which is determined by mixing order. We show that the neat 60/40 (PA6/POE) blend has an unstable co-continuous morphology which breaks up over time during annealing to a droplet-matrix morphology with POE being the continuous phase. The addition of 3 wt% graphene leads to co-continuous morphologies independent of mixing order. In the case of 80/20 systems, preparation of nanocomposites with a POE master batch resulted in elongated POE dispersed domains which becomes a co-continuous morphology at higher level of graphene content (1.5 wt%). However, we observed a decrease in the continuity of the POE phase in the nanocomposite containing 3%wt of graphene due to a reduction of coalescence. Our rheological and electrical measurements revealed that the graphene formed a stronger percolated structure in 80/20 blend containing 3 wt% of graphene in comparison to 60/40/3 nanocomposites, which resulted in lower electrical resistivity. The electrical percolation threshold in this system is 0.66 wt% which demonstrates that using graphene to induce co-continuity in a highly asymmetric composition is a promising approach to design electrically conductive blends with a very low percolation threshold.

Poly(vinylidene fluoride‐co‐hexafluorpropylene)/polyaniline conductive blends: Effect of the mixing procedure on the electrical properties and electromagnetic interference shielding effectiveness

AbstractPoly(vinylidene fluoride‐co‐hexafluoropropylene)/polyaniline (PVDF‐co‐HFP/PAni) conductive blends were prepared by two methodologies involving the in situ polymerization in two different media and dry blending approach using ball milling. Dodecylbenzenesulfonic acid (DBSA) was used both as surfactant and as protonating agent in PAni synthesis. X‐ray diffraction (XRD), scanning electron microscopy (SEM), ultraviolet–visible (UV–Vis) spectroscopy, and thermogravimetric analysis were used for characterizing the blends. PAni and PVDF/PAni prepared by in situ polymerization in H2O/toluene medium exhibited superior electrical conductivity, higher thermal stability and significantly higher electromagnetic interference shielding effectiveness (EMI SE) than those prepared in H2O/dimethylformamide (DMF) medium. PVDF/PAni with high‐PAni content (>40%) prepared by the dry blend approach presented higher conductivity and EMI SE than those prepared by in situ polymerization. The molding temperature exerted significant influence on the conductivity and EMI SE for the blend containing higher amount of PAni. The free‐solvent dry blending approach using ball milling presented similar conductivity value but the higher EMI SE when compared with in situ polymerization, and is considered environmentally and technologically interesting.

Carbon nanotubes to enable autonomous and volumetric self-heating in epoxy/polycaprolactone blends

Carbon nanotubes (CNT) were added to epoxy/polycaprolactone (PCL) blends in order to get electrically conductive blends. As it was expected, an increase of CNT content promotes a higher electrical conductivity due to the creation of more electrical pathways. Furthermore, it was observed that the enhancement is also observed with increasing PCL content, reaching values of around 0.2 S/m for 0.2 wt % CNT and 20 wt % PCL samples, due to its effect on rheological properties of the mixture, which affect positively to the CNT dispersion process, thus leading to more homogeneous and well dispersed nanocomposites, as observed by microstructural analysis. Thermal conductivity also increases with CNT content but decreases with PCL addition due to its insulating properties. A study of the voltage required to reach the above-mentioned self-healing temperature for each material has been performed by thermography monitoring. It has been observed that the samples with the highest amount of both CNT and PCL, have the best resistive heating capabilities due to a higher thermoresistive efficiency of the electrical network, reaching temperatures above 100 °C, at voltages below 150 V.

Fabrication of thermoplastic polyurethane and polyaniline conductive blend with improved mechanical, thermal and excellent dielectric properties: exploring the effect of ultralow-level loading of SWCNT and temperature

A novel multifunctional conductive blend and nanocomposites based on thermoplastic polyurethane (TPU), polyaniline (PANI) and carboxylic acid functionalized single-wall carbon nanotubes (SWCNT) with very high mechanical, thermal and excellent dielectric properties have been fabricated. The dispersion pattern and the interconnectivity of nanowire form of PANI and SWCNT in the TPU matrix are observed from HRTEM and FESEM photomicrographs. The interfacial interaction between the constituents in terms of hydrogen bonding has been confirmed from the FTIR and Raman spectra. The enhancement in tensile strength at 10 weight percentage (wt%) PANI loading explores the reinforcing nature of PANI on TPU matrix. The increase in thermal stability of the TPU/PANI blend in comparison with PANI again confirms the establishment of chemical linkages in the interface. The effect of PANI loading and temperature on the dielectric relaxation behavior has been explored in a wide range of frequency (1–106 Hz). The easiness in the polarization of the dipoles in PANI as well as in SWCNT has been confirmed from the improved value of dielectric permittivity (e′). The pronounced tunneling and hopping mode of conduction have reflected from conductivity (σac) and reduction in impedance (Z′ and Z″) value. The substantial improvement in e′ and σac of TPU/PANI/SWCNT nanocomposites at ultralow loading level of SWCNT (0.5wt %) in comparison with unfilled TPU/PANI blend is the uniqueness of this study. The effect of temperature on e′ and σac ensures the negative temperature coefficient (NTC) behavior of resistance of TPU/PANI blends.

Development of Poly(l-Lactic Acid)-Based Bending Actuators.

This work reports on the development of bending actuators based on poly(l-lactic acid) (PLLA)/ionic liquid (IL) blends, through the incorporation of 40% wt. of the 1-ethyl-methylimidazolium bis(trifluoromethylsulfonyl)imide ([Emim][TFSI]) IL. The films, obtained by solvent casting at room temperature and 50 °C, were subjected to several post-thermal treatments at 70, 90, 120 and 140 °C, in order to modify the crystallinity of the films. The influence of the drying temperature and of [Emim][TFSI] blending on the morphological, structural, mechanical and electrical properties of the composite materials were studied. The IL induced the formation of a porous surface independently of the processing conditions. Moreover, the [Emim][TFSI] dopant and the post-thermal treatments at 70 °C promoted an increase of the degree of crystallinity of the samples. No significant changes were observed in the degree of crystallinity and Young Modulus for samples with thermal treatment between 70 and 140 °C. The viability of the developed high ionic conductive blends for applications as soft actuators was evaluated. A maximum displacement of 1.7 mm was achieved with the PLLA/[Emim][TFSI] composite prepared at 50 °C and thermally treated at 140 °C, for an applied voltage of 10 Vpp, at a frequency of 100 mHz. This work highlights interesting avenues for the use of PLLA in the field of actuators.

Dielectric barrier discharge plasma induced surface modification of polyester/cotton blend fabrics to improve polypyrrole coating adhesion and conductivity

Electrically conductive polyester-cotton blend fabrics were prepared by plasma pre-treatment followed by oxidative in-situ chemical polymerization of pyrrole. Polyester-cotton blend fabrics were pre-treated with dielectric barrier discharge-atmospheric pressure plasma treatment to improve the binding of polypyrrole coating on polyester-cotton blend substrate. A range of gas mixtures in dielectric barrier discharge were employed to investigate the effects of different gases in plasma induced surface modification to the surface roughness, surface chemistry and hydrophilicity of the fabric. Polyester-cotton blend fabric’s topographical change was observed by means of scanning electron microscopy, wettability changes by wicking height measurements and chemical changes by X-ray photoelectron spectroscopy. Effect of the plasma treatment on binding strength was analyzed by studying abrasion resistance and surface resistivity. Results showed that increase in wettability and surface functionalization by oxygen functional groups contributed to improved adhesion (by 80% up to 2500 abrasion cycles), conductivity (by 65%) and atmospheric degradation (by 68% up to 4 months).

Development of Poly (vinylidene fluoride) and Polyaniline blend with high dielectric permittivity, excellent electromagnetic shielding effectiveness and Ultra low optical energy band gap: Effect of ionic liquid and temperature

Electrically conductive polymer blends have attracted profound attention as dielectric materials. However, achieving isotropic behavior, electrical stability and low current leakage is still challenging. Here we have synthesized a conductive polymer blend of Polyaniline (PANI) and Poly (vinylidene fluoride) (PVDF) exhibiting relatively high dielectric permittivity (εʹ) together with low band gap. Ionic liquid (IL) has been incorporated and the effect of IL in the dielectric properties are explored. The interfacial adhesion, morphology and the dielectric polarization of the blends are investigated. The electromagnetic shielding effectiveness (EMISE) of the conductive blends is studied in X-band frequency range. The electrical stability and decrease in current loss of the blends has been analyzed through I–V characteristics. The findings reveal that with increase in PANI loading in the temperature range of 25–100 °C and IL incorporation results in excellent dielectric properties for charge storage applications. The high efficiency of absorption and low transmission of electromagnetic radiation by the conductive blends is the main reason for excellent EMISE possessed by the systems which can be used for shielding applications in electronics. The increase in electrical stability and decrease in current leakage ability appear in the form of narrow band gap.