Controlling adhesion properties of SWCNT-PET films prepared by wet deposition

Carbon Nanotube Film Electrodes with Acrylic Additives: Blocking Electrochemical Charge Transfer Reactions

Carbon nanotubes (CNTs) processed into conductive films by liquid phase deposition technologies reveal increasing interest as electrode components in electrochemical device platforms for sensing and energy storage applications. In this work we show that the addition of acrylic latex to water-based CNT inks not only favors the fabrication of stable and robust flexible electrodes on plastic substrates but, moreover, sensitively enables the control of their electrical and electrochemical transport properties. Importantly, within a given concentration range, the acrylic additive in the films, being used as working electrodes, effectively blocks undesired faradaic transfer reactions across the electrode-electrolyte interface while maintaining their capacitance response as probed in a three-electrode electrochemical device configuration. Our results suggest a valuable strategy to enhance the chemical stability of CNT film electrodes and to suppress non-specific parasitic electrochemical reactions of relevance to electroanalytical and energy storage applications.

Adhesion of Single-Walled Carbon Nanotube Thin Films with Different Materials

Single-walled carbon nanotubes (SWCNTs) possess extraordinary physical and chemical properties. Thin films of randomly oriented SWCNTs have great potential in many opto-electro-mechanical applications. However, good adhesion of SWCNT films with a substrate material is pivotal for their practical use. Here, for the first time, we systematically investigate the adhesion properties of SWCNT thin films with commonly used substrates such as glass (SiO₂), indium tin oxide (ITO), crystalline silicon (C-Si), amorphous silicon (a-Si:H), zirconium oxide (ZrO₂), platinum (Pt), polydimethylsiloxane (PDMS), and SWCNTs for self-adhesion using atomic force microscopy. By comparing the results obtained in air and inert Ar atmospheres, we observed that the surface state of the materials greatly contributes to their adhesion properties. We found that the SWCNT thin films have stronger adhesion in an inert atmosphere. The adhesion in the air can be greatly improved by a fluorination process. Experimental and theoretical analyses suggest that adhesion depends on the atmospheric conditions and surface functionalization.

Transparent Conductive Flexible Trilayer Films for a Deicing Window and Self-Recover Bending Sensor Based on a Single-Walled Carbon Nanotube/Polyvinyl Butyral Interlayer

A flexible transparent conductive film (TCF) is an important component in many modern smart devices. Recent TCF is always fabricated based on indium tin oxide (ITO). However, the drawbacks of ITO (e.g., brittle nature, high cost, and resource scarcity) and the complex preparation process of TCF limit the massive production and further application of TCF. Herein, a facile and low-cost method is proposed to prepare flexible TCF. Rolls of single-walled carbon nanotubes (SWCNTs)/polyvinyl butyral (PVB) interlayer film were first fabricated by the roll-to-roll (R2R) spraying method. Then, the interlayer film was laminated between polycarbonate (PC) films (0.1 mm in thickness) to fabricate a transparent (80% optical transmittance) but flexible trilayer film. Such a prepared trilayer film shows multifunctional applications. For example, on the one hand, high conductivity and uniform distribution of resistance ensure that it can work as a deicing window with good performance at a low voltage. On the other hand, its flexibility, rapid self-recovery, and stable response enable it to be used as a bending sensor, which shows remarkable stability, repeatability, and durability. This study provides a facile method to fabricate TCF based on commercial but low-cost materials, which is suitable for industrial production and wide practical applications.

Conductive nanomaterials for 2D and 3D printed flexible electronics

This review describes recent developments in the field of conductive nanomaterials and their application in 2D and 3D printed flexible electronics, with particular emphasis on inks based on metal nanoparticles and nanowires, carbon nanotubes, and graphene sheets. We present the basic properties of these nanomaterials, their stabilization in dispersions, formulation of conductive inks and formation of conductive patterns on flexible substrates (polymers, paper, textile) by using various printing technologies and post-printing processes. Applications of conductive nanomaterials for fabrication of various 2D and 3D electronic devices are also briefly discussed.

Chemical Postdeposition Treatments To Improve the Adhesion of Carbon Nanotube Films on Plastic Substrates

The robust adhesion of single-walled carbon nanotubes (SWCNTs) to plastic substrates is a key issue toward their use in flexible electronic devices. In this work, semitransparent SWCNT films were prepared by spray-coating on two different plastic substrates, specifically poly(ethylene terephthalate) and poly(vinylidene fluoride). The deposited SWCNT films were treated by dipping in suitable solvents separately, namely, 53% nitric acid (HNO₃) and N-methyl pyrrolidone. Direct evidence of SWCNT adhesion to the substrate was obtained by a peel-off test carried out with an adhesive tape. Moreover, these treatments caused enhanced film transparency and electrical conductivity. Electron microscopy images suggested that SWCNTs were embedded in the plastic substrates, forming a thin layer of conductive composite materials. Raman spectroscopy detected a certain level of doping in the SWCNTs after the chemical treatments, which particularly affected metallic nanotubes in the case of the HNO₃ treatment. The microscopic adhesion and hardness of the SWCNT films were studied through a nanoscratch test. Overall, the efficiency of selected chemical postdeposition treatments for improving the SWCNT adhesion and the robustness of the resulting SWCNT films are demonstrated on flexible substrates of different chemical compositions.

Insights into the Interactions of Amino Acids and Peptides with Inorganic Materials Using Single-Molecule Force Spectroscopy

The interactions between proteins or peptides and inorganic materials lead to several interesting processes. For example, combining proteins with minerals leads to the formation of composite materials with unique properties. In addition, the undesirable process of biofouling is initiated by the adsorption of biomolecules, mainly proteins, on surfaces. This organic layer is an adhesion layer for bacteria and allows them to interact with the surface. Understanding the fundamental forces that govern the interactions at the organic-inorganic interface is therefore important for many areas of research and could lead to the design of new materials for optical, mechanical and biomedical applications. This paper demonstrates a single-molecule force spectroscopy technique that utilizes an AFM to measure the adhesion force between either peptides or amino acids and well-defined inorganic surfaces. This technique involves a protocol for attaching the biomolecule to the AFM tip through a covalent flexible linker and single-molecule force spectroscopy measurements by atomic force microscope. In addition, an analysis of these measurements is included.

Fabrication of durable and flexible single-walled carbon nanotube transparent conductive films

Highly flexible, durable, and transparent conducting films are fabricated from the de-bundled SWCNTs in aqueous solutions of SPES with high conductivity (125 Ω sq⁻¹) and good transmittance (87%) without adopting any binder or post treatment techniques.

Recent Advances in Controlling the Depositing Morphologies of Inkjet Droplets

Inkjet printing has been widely used in functional material patterning for fabrication of optical/electrical devices. The depositing morphologies of inkjet droplets are critical to the resolution and performance of resulted functional patterns. This review summarizes various strategies to control the depositing morphologies of inkjet droplets, including suppressing and utilizing coffee-ring effect, employing liquid substrates, developing patterned substrates and controlling droplets coalescence. Moreover, the remaining challenges in controlling inkjet droplets are presented, and the broad research and application prospects of controlling nanomaterial patterning by inkjet printing are proposed.