Preparation and tensile conductivity of carbon nanotube/polyurethane nanofiber conductive films based on the centrifugal spinning method

Flexible conductive thin films have recently become a research area of focus in both academia and industry. In this study, a method of preparing nanofiber conductive films by centrifugal spinning is proposed. Polyurethane (PU) nanofiber films were prepared by centrifugal spinning as the flexible substrate film, and carbon nanotubes (CNTs) were used as the conducting medium, to obtain CNTs/PU nanofiber conductive films with good conductivity and elasticity. The effects of different CNT concentrations on the properties of the nanofiber films were investigated. It was found that the conductivity of the nanofiber conductive films was optimal when an impregnation concentration of 9% CNTs was used in the stretching process. Cyclic tensile resistance tests showed that the nanofiber conductive films have good durability and repeatability. Physical and structural property analysis of the CNT/PU conductive films indicate that the adsorption of the CNTs on the PU surface was successful and the CNTs were evenly dispersed on the surface of the matrix. Moreover, the CNTs improved the thermal stability of the PU membrane. The CNT/PU conductive films were pasted onto a human finger joint, wrist joint, and Adam's apple to test the detection of movement. The results showed that finger bending, wrist bending, and laryngeal prominence movement all caused a change in resistance of the conductive film, with an approximately linear curve. The results indicate that the CNT/PU nanofiber conductive film developed in this study can be used to test the motion of human joints.

Size-Dependent Properties of Solution-Processable Conductive MOF Nanocrystals

The diverse optical, magnetic, and electronic behaviors of most colloidal semiconductor nanocrystals emerge from materials with limited structural and elemental compositions. Conductive metal-organic frameworks (MOFs) possess rich compositions with complex architectures, but remain unexplored as nanocrystals, hindering their incorporation into scalable devices. Here, we report the controllable synthesis of conductive MOF nanoparticles based on Fe(1,2,3-trizolate)2. Sizes can be tuned as small as 5.5 nm, ensuring indefinite colloidal stability. These solution-processable MOFs can be analyzed by solution-state spectroscopy and electrochemistry and cast into conductive thin films with excellent uniformity. This unprecedented analysis of MOF materials reveals a strong size-dependence in optical and electronic behavior sensitive to the intrinsic porosity and guest-host interactions of MOFs. These results provide a radical departure from typical MOF characterization, enabling insight into physical properties otherwise impossible with bulk analogs, while offering a roadmap for the future of MOF nanoparticle synthesis and device fabrication.

Self Standing Mats of Blended Polyaniline Produced by Electrospinning

Conducting nanofibers of polyaniline (PANI) doped with camphor-10-sulfonic acid (HCSA) and blended with different polymers, such as polymethyl methacrylate (PMMA) and polyvinyl acetate (PVAc), have been fabricated using the electrospinning technique. Scanning electron microscopy (SEM) and thermal gravimetric analysis (TGA) were utilized to characterize the morphology and the thermal stability of PANI-blended fibers. An extensive study was performed to understand the copolymer influence on both the structural and surface properties of the realized conductive thin films. Samples main electrical characteristics, as conductivity, specific capacitance and electrochemical performances were tested. The better mats were obtained with the use of PVAc copolymer, which showed a conductivity value two orders of magnitude higher than the PMMA system. Aiming at further improving the electrochemical features of these blended mats, hybrid fibers based on PANI/PVAc/graphene oxide and PANI/PVAc/iron oxide were also produced and characterized. The obtained mats were potentially addressed to numerous practical fields, including sensors, health applications, smart devices and multifunctional textile materials.

Sheet Resistance Measurements of Conductive Thin Films: A Comparison of Techniques

Conductive thin films are an essential component of many electronic devices. Measuring their conductivity accurately is necessary for quality control and process monitoring. We compare conductivity measurements on films for flexible electronics using three different techniques: four-point probe, microwave resonator and terahertz time-domain spectroscopy. Multiple samples were examined, facilitating the comparison of the three techniques. Sheet resistance values at DC, microwave and terahertz frequencies were obtained and were found to be in close agreement.

Equivalent Electrical Circuit Modeling of CNT-Based Transparent Electrodes

Among the various applications of carbon nanotubes (CNTs) that have been investigated since the discovery of their exceptional potential in the electronic field, great interest has been directed towards the creation of carbon-based materials capable of replacing Indium Tin Oxide (ITO) as a transparent electrode. Such transparent conductive films find application in touch panels, LCD screens, OLED displays, photovoltaic cells, and many others. This review presents a collection of techniques that have been proposed during the last decade for the modeling of carbon nanotube-based materials by means of equivalent electrical networks. These networks represent the electrical properties of CNT-based conductive thin films in a way that can be easily included in circuit simulators for the simulation-assisted design of the different devices under static and dynamic conditions.