Facile Preparation of Highly Conductive Poly(amide-imide) Composite Films beyond 1000 S m-1 through Ternary Blend Strategy

Optimization of PVDF-TrFE Based Electro-Conductive Nanofibers: Morphology and In Vitro Response

In this study, morphology and in vitro response of electroconductive composite nanofibers were explored for biomedical use. The composite nanofibers were prepared by blending the piezoelectric polymer poly(vinylidene fluoride-trifluorethylene) (PVDF-TrFE) and electroconductive materials with different physical and chemical properties such as copper oxide (CuO), poly(3-hexylthiophene) (P3HT), copper phthalocyanine (CuPc), and methylene blue (MB) resulting in unique combinations of electrical conductivity, biocompatibility, and other desirable properties. Morphological investigation via SEM analysis has remarked some differences in fiber size as a function of the electroconductive phase used, with a reduction of fiber diameters for the composite fibers of 12.43% for CuO, 32.87% for CuPc, 36.46% for P3HT, and 63% for MB. This effect is related to the peculiar electroconductive behavior of fibers: measurements of electrical properties showed the highest ability to transport charges of methylene blue, in accordance with the lowest fibers diameters, while P3HT poorly conducts in air but improves charge transfer during the fiber formation. In vitro assays showed a tunable response of fibers in terms of viability, underlining a preferential interaction of fibroblast cells to P3HT-loaded fibers that can be considered the most suitable for use in biomedical applications. These results provide valuable information for future studies to be addressed at optimizing the properties of composite nanofibers for potential applications in bioengineering and bioelectronics.

Self-Healing Silver Nanowires and Reduced Graphene Oxide/Polyurethane Composite Film Based on the Diels–Alder Reaction under Infrared Radiation

The hybrid composite of silver nanowires (AgNWs) and reduced graphene oxide (RGO) was synthesized in situ by an improved polyol–thermal method. The AgNWs-RGO with mass contents of 5–37 wt% was added into the thermo-reversible Diels–Alder reaction polyurethane (DA-PU) matrix with the AgNWs as the main conductor and the RGO as the auxiliary conductor to prepare self-healing composite conductive films. Further, the electrical conductivity, thermal conductivity, mechanical properties, infrared thermal response, and self-healing property of the composite film under infrared light irradiation were studied. The experimental results demonstrate that the AgNWs-RGO endows the composite film with good electrical and thermal conductivity and infrared thermal response ability, while the mechanical properties of the composite film decrease as the AgNWs-RGO mass content increases. The self-healing efficiency of the composite film is higher than that of the pure DA-PU under infrared light irradiation due to the good infrared photothermal response ability of the AgNWs-RGO. When the mass content of AgNWs-RGO in the composite film was 25 wt%, the AgNWs-RGO showed good dispersion in composite films, and the resistivity, thermal conductivity, and tensile strength of the composite film were 0.544 Ω·m, 0.3039 W·m⁻¹·K⁻¹, and 9.05 MPa, respectively. The infrared photothermal conversion temperature of the composite film is 158.5 °C (3450 lux for 1 min), and the infrared photothermal self-healing efficiency is 118% (3450 lux for 600 s). The AgNWs-RGO also improves the multiple self-healing ability of the composite film. The use of a high mass content of AgNWs-RGO in the composite film is beneficial in obtaining high multiple self-healing efficiencies. The first and the fifth infrared thermal self-healing efficiencies of the composite film with AgNWs-RGO of 35 wt% are 105% and 86%, respectively, and the resistivity of the composite film changes little and still maintains good conductivity.

Charge Transfer and Biocompatibility Aspects in Conducting Polymer-Based Enzymatic Biosensors and Biofuel Cells

Charge transfer (CT) is a very important issue in the design of biosensors and biofuel cells. Some nanomaterials can be applied to facilitate the CT in these bioelectronics-based devices. In this review, we overview some CT mechanisms and/or pathways that are the most frequently established between redox enzymes and electrodes. Facilitation of indirect CT by the application of some nanomaterials is frequently applied in electrochemical enzymatic biosensors and biofuel cells. More sophisticated and still rather rarely observed is direct charge transfer (DCT), which is often addressed as direct electron transfer (DET), therefore, DCT/DET is also targeted and discussed in this review. The application of conducting polymers (CPs) for the immobilization of enzymes and facilitation of charge transfer during the design of biosensors and biofuel cells are overviewed. Significant attention is paid to various ways of synthesis and application of conducting polymers such as polyaniline, polypyrrole, polythiophene poly(3,4-ethylenedioxythiophene). Some DCT/DET mechanisms in CP-based sensors and biosensors are discussed, taking into account that not only charge transfer via electrons, but also charge transfer via holes can play a crucial role in the design of bioelectronics-based devices. Biocompatibility aspects of CPs, which provides important advantages essential for implantable bioelectronics, are discussed.

Conducting Polymers in the Design of Biosensors and Biofuel Cells

Fast and sensitive determination of biologically active compounds is very important in biomedical diagnostics, the food and beverage industry, and environmental analysis. In this review, the most promising directions in analytical application of conducting polymers (CPs) are outlined. Up to now polyaniline, polypyrrole, polythiophene, and poly(3,4-ethylenedioxythiophene) are the most frequently used CPs in the design of sensors and biosensors; therefore, in this review, main attention is paid to these conducting polymers. The most popular polymerization methods applied for the formation of conducting polymer layers are discussed. The applicability of polypyrrole-based functional layers in the design of electrochemical biosensors and biofuel cells is highlighted. Some signal transduction mechanisms in CP-based sensors and biosensors are discussed. Biocompatibility-related aspects of some conducting polymers are overviewed and some insights into the application of CP-based coatings for the design of implantable sensors and biofuel cells are addressed. New trends and perspectives in the development of sensors based on CPs and their composites with other materials are discussed.

Polyurethane-Carbon Nanotubes Composite Dual Band Antenna for Wearable Applications

The design of a unipole and a dual band F-shaped antenna was conducted to find the best parameters of prepared antenna. Antenna radiator part is fully made of polymer and nonmetal base composite. Thermoplastic polyurethane (PU) was chosen as a matrix and multi-wall carbon nanotubes (MWCNT) as an electrical conductive filler, which creates conductive network. The use of the composite for the antenna has the advantage in simple preparation through dip coating technique. Minor disadvantage is the usage of solvent for composite preparation. Composite structure was used for radiator part of antenna. The antenna operates in 2.45 and 5.18 GHz frequency bands. DC conductivity of our PU/MWCNT composite is about 160 S/m. With this material, a unipole and a dual band F antenna were realized on 2 mm thick polypropylene substrate. Both antenna designs were also simulated using finite integration technique in the frequency domain (FI-FD). Measurements and full wave simulations of S11 of the antenna showed good agreement between measurements and simulations. Except for S11, the gain and radiation pattern of the antennas were measured and simulated. Maximum gain of the designed unipole antenna is around −10.0 and −5.5 dBi for 2.45 and 5.18 GHz frequency bands, respectively. The manufactured antennas are intended for application in wearable electronics, which can be used to monitor various activities such as walking, sleeping, heart rate or food consumption.

Simultaneous improvement of mechanical and conductive properties of poly(amide-imide) composites using carbon nano-materials with different morphologies

Two conductive carbon materials, one with a beaded-like structure (carbon black, ECP) and another with tube-like structure (functionalized multi-walled carbon nanotubes, FMWCNTs), were added into a poly(amide-imide) (PAI) matrix. Combining the advantages of ECP (good compatibility) and FMWCNT (high conductivity), the conductivity was improved from 3.7 S m−1 for PAI/FMWCNT polymer composites to 100 S m−1 for PAI/FMWCNT/ECP ternary conductive polymer composites, much higher than that of the sum of PAI/ECP and PAI/FMWCNT. The tensile strength increased from 40 to 70 MPa. The improved conductive and mechanical properties were mainly due to much more intensive conductive network produced in the PAI/FMWCNT/ECP ternary composites, which is useful for electron flow and stress spread. The number of hydrogen bond was increased by adding ECP into PAI/FMWCNT binary composites, and played an important role in forming the unique morphology as evident by Fourier transform infrared spectrometry (FTIR) and X-ray diffraction (XRD) measurements. These conductive composites have potential for flexible electronic applications.

Synthesis of Novel Thermostable Polyamideimides from Bis(2-aminoethyl)terephthalamide and Dianhydrides

Bis(2-aminoethyl)terephthalamide, an amide-containing diamine, was obtained from the aminolysis of waste poly(ethylene terephthalate) bottles. This diamine reacts with various aromatic dianhydrides to form novel polyamideimides (PAIs). The formation of amic acid or ammonium carboxylate salt intermediates depends strongly on the substituents of the dianhydrides. The electron-withdrawing substituents promote the creation of an ammonium carboxylate salt, whereas the electron donors assist with the amic acid intermediate formation. These salts and amic acids were further converted into polyimides by thermal treatment. The structures of the intermediates and PAIs were characterized by Fourier transform infrared, 1H nuclear magnetic resonance (NMR), and 13C NMR spectroscopies, and their thermal properties were determined by differential scanning calorimetry and thermogravimetry. X-ray diffraction patterns and inherent viscosity values of these PAIs were also reported. By using these chemical transformations, waste poly(ethylene terephthalate) bottles were converted into high-performance PAIs. These PAIs can be used as membrane-modifying agents for industrial separation applications.

Cost Effective Chemical Oxidative Synthesis of Soluble and Electroactive Polyaniline Salt and Its Application as Anticorrosive Agent for Steel

The cost effective synthesis of electroactive polyaniline (PANI) while retaining its desirable properties is one of the most debatable and challenging tasks for researchers in the field. Herein, we report a cost effective inverse emulsion polymerization pathway for the synthesis of soluble and processable PANI salt by using diesel as a novel dispersion medium. Different reaction parameters and their effects on the properties and yield of polyaniline were optimized. The polymer exhibited a highly porous morphology and was found to be stable up to 417 °C. The PANI salt showed good solubility in common solvents, such as chloroform, N-Methyl-2-pyrrolidone (NMP), dimethyl sulphoxide (DMSO) and in a 1:3 mixtures by volume of 2-propanol and toluene. The coating of the synthesized PANI salt on stainless steel has shown good corrosion resistant behavior in marine water by reducing the corrosion rate to 67.9% as compared to uncoated stainless steel.