Conducting Polymer Materials Research Articles

Research on Conductive Polymer Materials

With the continuous improvement of the national science and technology level, some advanced high-tech has been the focus of the country. It has played an important role in enhancing the lives of the people and improving their living habits. In particular, the technical means represented by Internet technology have completely subverted the past lifestyle. But for the development of the entire country, it is necessary to strengthen the research and development of industry and new material science, especially the research of conductive polymer materials. It is necessary to further strengthen capital investment and scientific and technological research and ensure that the entire development process is able to obtain large-scale applications of new materials. This article takes the research of conductive polymer materials as the topic through a comprehensive introduction to its concept, significance and effective application of polymer conductive materials. It aims to bring some references.

Design, fabrication and performance of flexible pressure sensors based on microstructures

With the rapid development of science and technology, electronic skin and flexible wearable devices have attracted wide attention because of their important applications in human motion, health monitoring, intelligent robots and other fields. The traditional pressure sensors based on noble metal or metal oxide semiconductor have high cost or poor flexibility, while the flexible pressure sensors based on microstructures have the advantages of high sensitivity, wide strain range, low cost, low power consumption and fast response, which play an important role in electronic skin and flexible wearable devices and have become one of the main research hotspots of materials and devices in flexible electronics. This review systematically summarizes the important progress made in the material selection, structural design, preparation methods and sensing performance of flexible pressure sensors based on different flexible substrate microstructures such as pyramid, microsphere, micro-column, bionic structure and fold and porous conductive polymer materials. Finally, the future development of flexible pressure sensors is prospected.

Conjugated Conductive Polymer Materials and its Applications: A Mini-Review.

Since their discovery 50 years ago, conjugated conducting polymers have received increasing attention owing to their unique conductive properties and potential applications in energy storage, sensors, coatings, and electronic devices such as organic field-effect transistors, photovoltaic cells, and light-emitting devices. Recently, these materials have played a key role in providing a more comfortable environment for humans. Consequently, the development of novel, high-performance conjugated conductive materials is crucial. In this mini-review, the progress of conjugated conductive materials in various applications and the relationship between the chemical structures and their performances is reviewed. This can aid in the molecular design and development of novel high-performance conjugated polymer materials.

Analysis on the Conductivity of Graphene-based Composite Material

Electric energy is the main energy source in production and life. How to make efficient transmission and utilization of electric energy is a problem that requires long-term research. Graphene, as a material with a single-layer two-dimensional honeycomb lattice carbon chain structure, has good electrical conductivity. Its composite with conductive polymer or inorganic metal materials can effectively improve its electrical conductivity and obtain more outstanding electrochemical performance. In order to understand the application of graphene’s electrical conductivity in life in more detail, this article first reviews the electrical properties of graphene, and then reviews and analyzes the research progress of graphene polymer electrical conductivity based on different composite materials and processing methods. The author also points out that the biggest problem facing graphene composites now is that the expensive price of graphene nanosheets and its unavailableness in large-scale applications and industrial production, as well as proposes that the future of graphene composites is still through scientific research in a short period of time. Continuously improving its electrical conductivity is necessary, yet the long-term strategic goal should be reducing the cost of industrialized production of graphene products and find the preparation conditions of graphene composite materials that are more suitable for industrial production.

Endowing Acceptable Mechanical Properties of Segregated Conductive Polymer Composites with Enhanced Filler-Matrix Interfacial Interactions by Incorporating High Specific Surface Area Nanosized Carbon Black.

Tuning the high properties of segregated conductive polymer materials (CPCs) by incorporating nanoscale carbon fillers has drawn increasing attention in the industry and academy fields, although weak interfacial interaction of matrix-filler is a daunting challenge for high-loading CPCs. Herein, we present a facile and efficient strategy for preparing the segregated conducting ultra-high molecular weight polyethylene (UHMWPE)-based composites with acceptable mechanical properties. The interfacial interactions, mechanical properties, electrical properties and electromagnetic interference (EMI) shielding effectiveness (SE) of the UHMWPE/conducting carbon black (CCB) composites were investigated. The morphological and Raman mapping results showed that UHMWPE/high specific surface area CCB (h-CCB) composites demonstrate an obviously interfacial transition layer and strongly interfacial adhesion, as compared to UHMWPE/low specific surface area CCB (l-CCB) composites. Consequently, the high-loading UHMWPE/h-CCB composite (beyond 10 wt% CCB dosage) exhibits higher strength and elongation at break than the UHMWPE/l-CCB composite. Moreover, due to the formation of a densely stacked h-CCB network under the enhanced filler-matrix interfacial interactions, UHMWPE/h-CCB composite possesses a higher EMI SE than those of UHMWPE/l-CCB composites. The electrical conductivity and EMI SE value of the UHMWPE/h-CCB composite increase sharply with the increasing content of h-CCB. The EMI SE of UHMWPE/h-CCB composite with 10 wt% h-CCB is 22.3 dB at X-band, as four times that of the UHMWPE/l-CCB composite with same l-CCB dosage (5.6 dB). This work will help to manufacture a low-cost and high-performance EMI shielding material for modern electronic systems.

Highly thermo-conductive yet electrically insulating material with perpendicularly engineered assembly of boron nitride nanosheets

With rapid evolution of advanced microelectronic devices, thermally conductive polymeric materials with impressive through-plane thermal conductivity (κ⊥) and remarkable electrical insulating properties are urgently demanded for efficient thermal management. Assembly of boron nitride nanosheets (BNNS) into polymer matrix with vertically interconnected conformation was usually adopted. However, impeded by inferior oriented degree and insufficient overlapped interconnection of BNNS, polymer/BNNS nanocomposites still suffered from a limited enhancement of κ⊥. In this work, we firstly prepared regenerated cellulose (RC)/BNNS filaments with high thermal conductivity via wet-spinning method. Then, a tailored polydimethylsiloxane (PDMS)/(RC/BNNS) filaments nanocomposite with hierarchical assembled architectures is successfully fabricated with customized-mold vacuum impregnation. Numerous bunches of macroscopical hybrid filaments penetrate through the nanocomposite from the bottom to the up, while vertically aligned microscopical BNNS with efficient filler interconnections confined within filaments provide many uniaxial thermal pathways. Attributed to tactfully engineered phonon pathways, the as-prepared material exhibits a remarkable κ⊥ up to 5.13 W/m K at 27.05 vol% BNNS loading, outperforming the characters in most literatures. Along with excellent electrical resistance and extraordinary thermal management performances, this type of nanocomposite with hierarchical structures provides an effective strategy to thickness-direction heat transfer issues of electronic devices.

Thermoplastic polyurethane/CNT nanocomposites with low electromagnetic resistance property

Multi-wall carbon nanotubes (MWCNTs) at 0.5 wt% to 2 wt% proportions were added to thermoplastic polyurethane (TPU) synthesized with polycarbonatediol (PCDL), 4,4’-methylene diphenyl diisocyanate (MDI), and 1,3-butanediol(1,3-BDO). To formulate a new TPU-MWCNT nanocomposite, the composite was melt-blended with a twin-screw extruder. To ensure the even dispersion of MWCNTs, dispersant (ethylene acrylic ester terpolymer; Lotader AX8900) of equal weight proportion to the added MWCNTs was also added during the blending process. Studies on the mechanical and thermal properties, and melt flow experiments and phase analysis of TPU-MWCNT nanocomposites, these nanocomposites exhibit higher tensile strength and elongation at break than neat TPU. TPU-MWCNT nanocomposites with higher MWCNT content possess higher glass-transition temperature (Tg), a lower melt index, and greater hardness. Relative to neat TPU, TPU-MWCNT nanocomposites exhibit favorable mechanical properties. By adding MWCNTs, the tensile strength of the nanocomposites increased from 7.59 MPa to 21.52 MPa, and Shore A hardness increased from 65 to 81. Additionally, TPU-MWCNT nanocomposites with MWCNTs had lower resistance coefficients; the resistance coefficient decreased from 4.97 × 1011 Ω/sq to 2.53 × 104 Ω/sq after adding MWCNTs, indicating a conductive polymer material. Finally, the internal structure of the TPU-MWCNT nanocomposites was examined under transmission electron microscopy. When 1.5 wt% or 2 wt% of MWCNTs and dispersant were added to TPU, the MWCNTs were evenly dispersed, with increased electrical conductivity and mechanical properties. The new material is applicable in the electronics industry as a conductive polymer with high stiffness.

Theory of ionic conductivity with morphological control in polymers.

We present a general theory of ionic conductivity in polymeric materials consisting of percolated ionic pathways. Identifying two key length scales corresponding to inter-path permeation distance ξ and one-dimensional hopping conduction path length mλ, we have derived closed-form formulas in terms of the energy U required to unbind a conductive ion from its bound state and the partition ratio ξ/mλ between the three-dimensional permeation and one-dimensional hopping pathways. The results provide design strategies to significantly enhance ionic conductivity in single-ion conductors. For large barriers to dissociate an ion, corrections to the Arrhenius law are presented. The predicted dependence of ionic conductivity on the unbinding time is in agreement with results in the literature based on simulations and experiments. This theory is generally applicable to conductive systems where the two mechanisms of permeation and hopping occur concurrently.

Maintaining electrical conductivity of microcellular MWCNT/TPU composites after deformation

Along with stretching ability, maintaining good electrical conductivity has become one of the most desirable properties for the next-generation electronics. Although various fabrication methods have been suggested, the greatest obstacle is their feasibility for large-scale production with low cost. In this study, highly stretchable and conductive MWCNT/TPU composite foams were fabricated by an industrially viable technique, melt compounding followed by supercritical fluid treatment and physical foaming. It was demonstrated that the introduction of a microcellular structure can significantly suppress increase in the electrical resistance with stretching. The 3.1 vol% MWCNT/TPU composite exhibited electrical conductivity of 9.5 × 10−4 S/cm, which reduced to 1.7 × 10−5 S/cm with 100% stretching. The creation of 26% void fraction increased the conductivity to 1.9 × 10−3 S/cm and assisted in maintaining a constant level of the electrical conductivity with 100% stretching. This is attributed to the localized deformation around the cells. Since the deformation is localized around the cells, the filler interconnections away from the cells are less deformed, and hence can maintain a high level of electrical conductivity. It was further found that the effect of localized deformation enhances the elongating ability of the MWCNT/TPU composites. This study shows that the generation of a microcellular structure offers a very effective way of fabricating highly stretchable and conductive polymeric materials for future electronics.

Improvement of the Optoelectrical Properties of a Transparent Conductive Polymer via the Introduction of ITO Nanoparticles and Its Application in Crystalline Silicon/Organic Heterojunction Solar Cells.

Compared with conventional transparent conductive indium tin oxide (ITO) films, poly(3,4-ethylenedioxythiophene):poly (styrenesulfonic acid) (PEDOT:PSS) as a conductive polymer material has been diffusely applied in organic optoelectronic devices. However, its optoelectrical properties need to be further improved. Therefore, a simple and universal approach with introducing ITO nanoparticles (NPs) was proposed to improve the optoelectrical properties of PEDOT:PSS thin films. The results show that the vertical conductivity (σDC⊥) and average transmittance (from 300 to 1200 nm) of PEDOT:PSS films were enhanced about 26.8 and 6.3%, respectively. Crystalline silicon (c-Si)/organic heterojunction solar cells (HSCs) with PEDOT:PSS/ITO NP hybrid films were fabricated and performances led to further improvement. The spatial distributions of relative electrical field intensity and the carrier generation rate of the HSCs under the standard AM 1.5 G condition were simulated, which were in good agreement with the experimental conclusions.

General design criteria for neonatal temperature monitoring sensor using "smart material" conducting polymer development: A review

Surface thermistors are being currently used in patient monitoring, including temperature monitoring among neonates. However, these thermistors are reported as being mechanically rigid. This review article aims to provide researchers with a guide to better design a flexible neonatal temperature monitoring sensor. A literature search was conducted to obtain available literature on temperature sensors with specific attention to designing flexible temperature sensors. The achievement of a flexible type thermistor for neonates requires a basic understanding of the thermistor. Also, the conducting polymer material being used and the rationale for their placement. The updated technology in thermistors should be made flexible for the ease of neonates during monitoring. Careful considerations for the design and conduct of flexible temperature sensor research as outlined in this review would help to enhance the quality and comparability of future research studies. Considerations for efficient neonatal temperature monitoring and protection include accuracy, sensor's size, weight, material, and sensor placement. Flexible sensors could be the alternative to conventional bulky and stiff temperature sensors.

Electropolymerized Poly(3,4-ethylenedioxythiophene)/Screen-Printed Reduced Graphene Oxide-Chitosan Bilayer Electrodes for Flexible Supercapacitors.

An electropolymerized poly(3,4-ethylenedioxythiophene) (PEDOT)/screen-printed reduced graphene oxide (rGO)–chitosan (CS) bilayer material was coated on carbon cloth to form electrodes for gel-electrolyte flexible supercapacitors. The conductive polymer and carbon-based materials mainly contribute pseudocapacitance (PC) and electrical double-layer capacitance (EDLC), respectively. The high porosity and hydrophilicity of the PEDOT/rGO–CS bilayer material offers a large contact area and improves the contact quality for the gel electrolyte, thereby enhancing the capacitive performance. Cyclic voltammetry (CV) under a potential scan rate of 2 mV/s revealed that a maximum areal capacitance of 1073.67 mF/cm2 was achieved. The capacitance contribution ratio PC/EDLC was evaluated to be ∼67/33 by the Trasatti method. A 10,000-cycle CV test showed a capacitance retention rate of 99.3% under a potential scan rate of 200 mV/s, indicating good stability. The areal capacitance remains similar under bending with a bending curvature of up to 1.5 cm–1.

Enhanced Thermal Conductivity in Oriented Polyvinyl Alcohol/Graphene Oxide Composites.

Polymer composites have attracted increasing interest as thermal management materials for use in devices owing to their ease of processing and potential lower costs. However, most polymer composites have only modest thermal conductivities, even at high concentrations of additives, resulting in high costs and reduced mechanical properties, which limit their applications. To achieve high thermally conductive polymer materials with a low concentration of additives, anisotropic, solid-state drawn composite films were prepared using water-soluble polyvinyl alcohol (PVA) and dispersible graphene oxide (GO). A co-additive (sodium dodecyl benzenesulfonate) was used to improve both the dispersion of GO and consequently the thermal conductivity. The hydrogen bonding between GO and PVA and the simultaneous alignment of GO and PVA in drawn composite films contribute to an improved thermal conductivity (∼25 W m–1 K–1), which is higher than most reported polymer composites and an approximately 50-fold enhancement over isotropic PVA (0.3–0.5 W m–1 K–1). This work provides a new method for preparing water-processable, drawn polymer composite films with high thermal conductivity, which may be useful for thermal management applications.

General synthesis of hollow mesoporous conducting polymers by dual-colloid interface co-assembly for high-energy-density micro-supercapacitors

Rational design and precise regulation over the morphology, structure, and pore size of functional conducting mesoporous polymers with enriched active sites and shorten electron–ion transport pathway are extremely important for developing high-performance micro-supercapacitors (MSCs), but still remain a great challenge. Herein, a general dual-colloid interface co-assembly strategy is proposed to fabricate hollow mesoporous polypyrrole nano-bowls (mPPy-nbs) for high-energy-density solid-state planar MSCs. By simply adjusting the size of block copolymer micelles, the diameter of polystyrene nanospheres and the amount of pyrrole monomer, mesopore size of the shell, void and shell thickness of mPPy-nbs can be simultaneously controlled. Importantly, this strategy can be further utilized to synthesize other hollow mesoporous polymers, including poly(tris(4-aminophenyl)amine), poly(1,3,5-triaminobenzene) and their copolymers, demonstrative of excellent universality. The structurally optimized mPPy-nb exhibits high specific surface area of 122 m2 g−1and large capacitance of 225 F g−1 at 1 mV s−1. Furthermore, the MSCs assembled by mPPy-nbs deliver impressive volumetric capacitance of 90 F cm−3 and energy density of 2.0 mWh cm−3, superior to the most reported polymers-based MSCs. Also, the fabricated MSCs present excellent flexibility with almost no capacitance decay under varying bending states, and robust serial/parallel self-integration for boosting voltage and capacitance output. Therefore, this work will inspire the new design of mesoporous conducting polymer materials toward high-performance microscale supercapacitive devices.

Synthesis of shape memory electroconductive polyurethane with self-healing capability as an intelligent biomedical scaffold for bone tissue engineering

Electrically conductive polymeric materials are known as a special class of intelligent bioactive materials capable of regulating cellular behaviors of human adipose-derived mesenchymal stem cells, especially their differentiation to bone tissue. Here the synthesis of electroactive self-healing polyurethane scaffolds (PUAT) with shape memory ability based on aniline trimer and disulfide bonds are reported. The prepared scaffolds were characterized by FTIR, tensile test, water contact angle, electrical conductivity, and degradation test. The PUAT5 scaffold (containing 5% aniline trimer) exhibited excellent self-healing (>95%) and shape memory properties with shape recovery ratio (>95%, ~30 s at 40 °C) and shape fixity ratio (>96%) at a temperature close to the physiological temperature. The PUAT5 significantly promote the human adipose-derived mesenchymal stem cell adhesion and proliferation compared to PUAT0 and TCP. Also, the gene expression level of RUNX2, COL1, ALP, and OCN of PUAT5 were significantly enhanced after 21 days, in line with the increased maturity of extracellular matrix and mineralization. Furthermore, almost 75% of the bone volume has been recovered at 8 weeks post-surgery while the control group showed 26% recovery. The In vitro and In Vivo results suggested that these multifunctional engineered constructs have great potential in repairing various bone defects.

Research progress of microextraction by packed sorbent and its application in microvolume sample extraction

微萃取技术是分析化学领域发展迅速,且已经得到广泛应用的样品前处理技术。填充吸附剂微萃取(MEPS)是一种微量固相萃取技术,使用微量的吸附剂填充于微量注射器,通过反复抽推方式使样品多次流经吸附剂以完成样品吸附萃取过程,萃取后的样品可直接用于色谱分析。典型的MEPS萃取设备包括MEPS注射器和MEPS吸附床(BIN)。MEPS优化的主要因素为MEPS处理过程的参数,包括样品流速、样品量与样品萃取循环次数,吸附剂及淋洗、洗脱溶剂的种类和体积,还需要考虑样品基质对MEPS性能的影响和样品残留和重复使用问题。MEPS中最重要的部分是吸附剂,主要有商品化的MEPS吸附剂,包括硅基的Silica、C18、C8等,碳材料的Hypercarb和聚苯乙烯聚合物类的SDVB、HDVB吸附剂等。研究用的吸附剂包括分子印迹材料、限进分子印迹材料、碳基材料、导电聚合物类材料、改性硅基材料及共价-有机骨架材料等。MEPS结合多种分析仪器已经成功应用于从不同基质中提取单一或多种分析物,所涵盖基质包括生物样品(尿液、唾液、血浆或血液)、河流水体或生活污水以及几种食品和饮料。MEPS处理复杂生物基质样品时,通常需要稀释样品、除蛋白质等预处理。MEPS具有需要样品体积小、操作快速等特点,在生物基质样品分析中有望得到更广泛的使用。在环境样品中,该技术可与现场便携仪器联用,未来将有望在现场进行快速检测,并于易分解样品等方面发挥作用。

Reversible Intercalation of Al‐Ions in Poly(3,4‐Ethylenedioxythiophene):Poly(4‐Styrenesulfonate) Electrode for Aqueous Electrochemical Capacitors with High Energy Density

Due to the high capacity of the three‐electron redox mechanism, Al‐ions‐based energy‐storage devices have the potential to provide a viable solution to meet the growing demand for powering electronic products. However, discovering suitable electrode materials for reversible insertion of Al ions remains a difficult task. Herein, it is reported that a classical conductive polymeric material poly(3,4‐ethylenedioxythiophene):poly(4‐styrenesulfonate) (PEDOT:PSS) can perform the reversible Al‐ions intercalation for aqueous electrochemical capacitors. The as‐prepared PEDOT:PSS film on a carbon cloth composite electrode exhibits a large magnitude of faradaic currents and sharp redox peaks in cyclic voltammetry (CV) curves in aluminum sulfate electrolyte, and delivers a high capacitance of 269 F g−1 (78 mAh g−1). Diffusion‐controlled Al‐ions intercalation/deintercalation as the charge‐storage mechanism is demonstrated here, which is not observed in other ions‐based electrolytes (H+, Mg2+, Li+, Na+). An asymmetric electrochemical capacitor based on Al ions, composed of such an electrode and activated carbon electrode is assembled and displays a high energy density of 41.6 Wh kg−1 at a power density of 0.24 kW kg−1, demonstrating a promising aqueous electrochemical capacitor with an advanced energy density via polyvalent ions intercalation.

Hand-extended noodle inspired physical conjoined-network organohydrogels with anti-freezing, high stiffness and toughness properties

To obtain excellent anti-freezing, non-drying, mechanical properties and conductivity of polymeric materials is important and necessary to realize their wide applications in the fields of sensor and smart wearable devices. However, it is very difficult to keep all these performances well due to the antagonistic action in different properties. Herein, inspired by the Chinese hand-extended noodles that salt and cooking oil enhance the elasticity, stretchability, and non-drying, a new strategy to fabricate conjoined-network organohydrogel with multiple excellent performances is reported. By dissolving calcium chloride (CaCl2, as ‘salt’) into glycerol/water solution (as ‘oil’) as solvent, a physical conjoined-network organohydrogel composed of polyvinyl alcohol (PVA) and sodium alginate (Alg) with excellent performance was fabricated by a simple gelation and soaking two-step strategy. Under the synergy of CaCl2 and glycerol, the organohydrogel shows excellent anti-freezing performance below −42.1 °C, well non-drying property (72 h), outstanding mechanical properties (tensile strength of 2.11 MPa, elongation at break of 580% and Young’s modulus of 0.42 MPa), and well ionic conductivity (1.69 S m−1) by construct a conjoined-network, which provides a general strategy for the design of hydrogels with multiple outstanding performances due to a variety of the cross-linking mechanisms available and synergistic effect. It was foreseen that the conjoined-network organohydrogel might be widely used in multiple areas such as electric skin, artificial intelligence, and smart wearable devices.

Thermal and Electrical behaviors of Boron Nitride/Epoxy reinforced polymer matrix composite—A review

AbstractIn electronic and electric instruments, heat dissipation is one of the major issues that degrade performance and efficiency. Polymer material has high specific strength and modulus, and it is mainly used in electrical insulation materials due to easy processability and light in weight with great flexibility but has low thermal conductivity. This paper examines the recent developments in highly thermal conductive epoxy‐based polymer composites. First, the composite materials, with applications, are briefly introduced. Second, the thermally conductive polymer types with their thermal conductivity are summarized. Third, the thermal and electric properties of different boron nitride (BN) with epoxy‐filled composite are listed. It also focuses on enhancement in thermal conductivity and electrical insulation, which are mainly influenced by the microstructure and amount of filler content. Some highly thermal conductive BN polymer based composites are reviewed. Fourth, various thermal conductivity measurement techniques are listed with their drawbacks. Finally, the review gives current scenario on thermal conductive polymer materials and developments needed with challenges in this area.

Liquid‐crystalline behavior and thermal conductivity of vinyl polymers containing benzoxazole side groups

AbstractA series of methacrylamides containing benzoxazole (BO) mesogenic side groups and different lengths of alkyl units was synthesized in this study. A methacrylamide containing the n‐dodecyl group was selected as a suitable monomer to obtain beneficial thermally conductive polymeric materials because of its sufficient solubility in toluene in the subsequent radical polymerization and because of its liquid crystallinity. This methacrylamide led to a highly soluble polymer with film‐forming ability. The BO‐containing polymethacrylamide also exhibited liquid‐crystalline (LC) behavior during the heating and cooling processes. The cast film was kept at a slightly lower temperature than the clearing temperature and quenched to room temperature. This procedure afforded a film maintaining optical anisotropy at room temperature, implying that a frozen LC structure is maintained at room temperature. The quenched film also resulted in a significantly enhanced thermal conductivity (λ = 0.60 W m−1 K−1) without the aid of fillers and external fields, unlike the as‐cast counterpart without optical anisotropy. A polyacrylate containing a flexible long alkylene (C6) spacer between the main chains and a BO‐containing mesogenic side group was also investigated. The polyacrylate exhibited LC behavior during the heating and cooling processes over wide ranges. The polyacrylate film quenched from an established temperature, which contains a frozen LC structure, also exhibited a significantly enhanced λ value (0.63 W m−1 K−1) without fillers and external fields. Thus, the BO‐containing vinyl polymers studied in this work are promising candidates for novel heat‐releasing materials. © 2020 Society of Chemical Industry