Conductive Nanocomposite Materials Research Articles

Conductive Nanocomposites Based on Graphene and Natural Polymers

This thesis focuses on the development of conductive nanocomposite materials based on graphene and natural polymers such as cellulose and chitosan. Graphene, a single layer of carbon atoms arranged in a honeycomb lattice, exhibits exceptional electrical, mechanical, and thermal properties, making it an attractive filler for polymer composites. However, the challenge lies in effectively dispersing graphene sheets within polymer matrices. The work presented explores new strategies for grafting polysaccharide chains onto oxidized graphite (graphene oxide) to improve its compatibility and dispersion in cellulose and chitosan matrices. The resulting composites were doped with gold or nickel nanoparticles to further enhance their electrical and catalytic properties. Detailed characterization techniques, including spectroscopic and microscopic methods, were employed to analyze the structure, morphology, and properties of the developed nanocomposites. The thesis is organized into three main parts: 1) a literature review on graphene, polysaccharides, and their biocomposites; 2) a description of the experimental materials and methods; and 3) a scientific discussion of the results, presented in the form of three research publications. The findings demonstrate the successful synthesis of conductive nanocomposites with improved compatibility and performance, opening up new avenues for the application of these sustainable and multifunctional materials in areas such as electronics, catalysis, and electromagnetic shielding.

Partially oxidized polyvinyl alcohol + functionalized water soluble multiwalled carbon nanotubes: A new conductive nanocomposite material with promising implications for neuroregeneration

Carbon nanotubes (CNT) are promising electroconductive nano-scale materials for neuroregeneration. Herein, we report on a new electroconductive composite scaffold made of the polymer 1% oxidized polyvinyl alcohol (OxPVA) combined with functionalized water soluble multiwalled CNT (OxPVA + MWCNT-S) (diazotization reaction). Preliminarily, MWCNT-S were characterized to evaluate the reaction outcome, the degree of functionalization and the dispersibility in water. Thereafter, OxPVA + MWCNT-S nanocomposite membranes were fabricated and analyzed for physicochemical properties (Raman spectroscopy, thermal decomposition, calorimetric properties, electroconductivity), macroscopic appearance and ultrastructure, mechanical behavior, in vitro cytotoxicity and in vivo biocompatibility. In parallel, OxPVA + MWCNT-S membranes with a linear pattern were also developed and analyzed for interaction with SH-SY5Y cells. Compared to OxPVA, the presence of MWCNT-S (only 0.016 wt%) significantly increased polymer conductivity and imparted a certain porosity without altering mechanical behaviour, as corroborated by uniaxial tensile tests. Neither cytotoxicity nor local signs of inflammation were detected in vitro and after subcutaneous implantation (14 and 42 days), proving composite material biocompatibility. OxPVA + MWCNT-S nanocomposite revealed as promising for future electroconductive conduits free from toxic effects amenable to CNT agglomeration within the polymer. Ideally, nerve lesions with wide gaps, may be effectively supported by those “active” devices, overcoming limitations of the available ones. Despite preliminary data, the presence of a linear pattern confirmed to have a beneficial effect over the scaffold/cells interaction.

Self-healable and super-stretchable conductive elastomeric nanocomposites for efficient thermal management characteristics and electromagnetic interference shielding

Due to the pressing need to mitigate current electromagnetic wave pollution (connecting to the 5 G era), lightweight, stretchable, thermally, and electrically conductive nanocomposite materials have attracted significant scientific interest. Herein, self-healable carboxylated nitrile butadiene elastomeric (XNBR) based nanocomposites were fabricated via sequential wet cum melt mixing technique utilizing multi-walled carbon nanotubes (MWCNTs). The metal-ligand complexes in the XNBR elastomer chain endow a reversible network that leads to self-healing ability. The higher aspect ratio of MWCNTs assists in constructing interconnected conductive pathways inside the XNBR matrix. The nanocomposite with MWCNTs (15 phr) provided an excellent EMI shielding effectiveness of − 27.4 dB, whereas the nanocomposite exhibited a thermal conductivity of 0.85 W.m−1. K−1. Interestingly, the interconnected networking pathway of MWCNTs in the XNBR matrix prepared a tunable analogical structure providing an absorption-dominant shielding mechanism. Under severe practical and environmental testing conditions, the nanocomposites showed a minute change in electromagnetic effectiveness, demonstrating their good performance for outdoor applications. These ultra-lightweight, self-healable, recyclable MWCNTs/ XNBR EMI shields are promising materials for next-generation super-stretchable and portable smart electronics.

Data‐Driven Design of Electrically Conductive Nanocomposite Materials: A Case Study of Acrylonitrile–Butadiene–Styrene/Carbon Nanotube Binary Composites

Electrically Conductive Nanocomposite Materials In article number 2200399, Boseok Kang, Jong Hwan Ko, and co-workers have developed an artificial intelligence (AI) system predicting various physical properties of carbon nanotube (CNT) / acrylonitrile-butadiene-styrene (ABS) nanocomposites by training the model with data collected from online literature. The AI model not only predicts physical properties of the nanocomposites when manufacturing information is given, but also conversely determines manufacturing conditions for the nanocomposites with desired physical properties. This demonstrates that AI-supported material development systems would be expanded into various applications in composite manufacturing.

Conductance-strain behavior in silver-nanowire composites: network properties of a tunable strain sensor

Highly flexible and conductive nano-composite materials are promising candidates for stretchable and flexible electronics. We report on the strain–resistance relation of a silver-nanowire photopolymer composite during repetitive stretching. Resistance measurements reveal a gradual change of the hysteretic resistance curves towards a linear and non-hysteretic behavior. Furthermore, a decrease in resistance and an increase in electrical sensitivity to strain over the first five stretching cycles can be observed. Sensitivity gauge factors between 10 and 500 at 23% strain were found depending on the nanowire concentration and stretching cycle. We model the electrical behavior of the investigated silver nanowire composites upon repetitive stretching considering the strain induced changes in the local force distribution within the polymer matrix and the tunnel resistance between the nanowires by using a Monte Carlo method.

Versatile Multi-Functional Block Copolymers Made by Atom Transfer Radical Polymerization and Post-Synthetic Modification: Switching from Volatile Organic Compound Sensors to Polymeric Surfactants for Water Rheology Control via Hydrolysis.

Novel, multipurpose terpolymers based on styrene (PS), tert-butyl methacrylate (tBMA) and glycidyl methacrylate (GMA), have been synthesized via Atom Transfer Radical Polymerization (ATRP). Post-synthetic modification with 1-pyrenemethylamine (AMP) allows non-covalent functionalization of carbon nanotubes, eventually yielding a conductive nanocomposite materials capable of interacting with different Volatile Organic Compounds (VOCs) by electrical resistance variation upon exposure. Moreover, facile hydrolysis of the tBMA group yields polyelectrolytic macrosurfactants with remarkable thickening properties for promising applications in water solution, such as Enhanced Oil Recovery (EOR).

Direct 3D Printing of Graphene Nanoplatelet/Silver Nanoparticle‐Based Nanocomposites for Multiaxial Piezoresistive Sensor Applications

AbstractAs a new area of biological integration systems ranging from fitness to costume, arable electronic devices are extensively investigated and recently focused on the development of customized and highly interactive devices with human‐friendly factors. Here, a facile method of integrating a three‐dimensional printing (3DP) with stretchable and conductive nanocomposite materials to form a multiaxial piezoresistive sensor that can detect human motion is presented. The multiaxial piezoresistive sensors are fabricated through direct 3DP of nanocomposites based on graphene nanoplatelets (GNPs), silver nanoparticles (AgNPs), and polyurethane. The sensor can detect not only compression, but also tensile strain upto more than 160%. Based on the synergy between GNPs and AgNPs, the sensor shows high sensitivity with a gauge factor of 48.2, which is a much higher value considering that most of the previously reported stretchable strain sensors are less than 35. In addition to the high sensitivity, the GNPs/AgNPs nanocomposite sensor exhibits a fast response time and excellent stability over 500 cycles. When the sensor is integrated into an LED light system, it functions as an interactive device that can control the intensity of light by detecting various human motions such as the bending of fingers.

Flexible UWB organic antenna for wearable technologies application

New generations of printed flexible antennas are playing an important role in wireless communication systems. The ultra wide band and wearable possibilities are critical aspects of these kinds of antennas. In this study, the proposed antenna is an elliptical monopole fed by a coplanar waveguide; it uses a kapton substrate and it is optimised to work from 1 to 8 GHz. In the case of copper, a conductive nanocomposite material based on a polymer (polyaniline: PANI) and charged by multiwalled carbon nanotubes (MWCNTs) is exploited. The flexibility of both the kapton substrate and the nanocomposite (PANI/MWCNTs) provides the ability to crumple the antenna paving the way to potential applications for body-worn wireless communications systems. In this study, the performance of the antenna is investigated in terms of return loss, radiation patterns and gain for both crumpled and uncrumpled antennas. The results confirm that performance remains at a good level when the antenna is crumpled.

Design and Characterization of Conductive Biopolymer Nanocomposite Electrodes for Medical Applications

Metal-based electrodes, despite being the most widely used for biomedical applications, are limited by a poor reliable skin-surface interface and patients suffer from comfort issues. The most common problems/inconveniences are caused by stiff electrodes, skin irritation, allergic reaction or corrosion. In order to overcome these problems, we produced and tested flexible electrodes involving biopolymer nanocomposite materials. Conductive polymers have been intensively studied and applied in the field of organic photovoltaics and flexible organic electronics. Recently, the use of conductive biopolymer nanocomposite has also emerged as an interesting and promising material for biomedical applications. In this study, we have designed and characterized electrodes made of a flexible and conductive nanocomposite material using a biocompatible and biodegradable polymeric matrix of poly (3-hydroxyalkanoate) (PHA, in particular poly (3-hydroxybutyrate), PHB) containing conductive nanowires. The biopolymer nanocomposites and their electrical conductivities were investigated by optical microscopy, scanning electron microscopy (SEM) and electrical four-point probing. The electrical conductivities obtained in the different PHA-polymer nanocomposites containing different concentrations of conductive additives is discussed in relation to the nanocomposite structure at the microscopic level. Finally, our developed biopolymer nanocomposite prototype electrodes have successfully been tested for transcutaneous electrical nerve stimulation (TENS) and electrocardiography ECG applications in comparison to conventional electrodes.

Conducting shrinkable nanocomposite based on au-nanoparticle implanted plastic sheet: tunable thermally induced surface wrinkling.

A thermally shrinkable and conductive nanocomposite material is prepared by supersonic cluster beam implantation (SCBI) of neutral Au nanoparticles (Au NPs) into a commercially available thermo-retractable polystyrene (PS) sheet. Micronanowrinkling is obtained during shrinking, which is studied by means of SEM, TEM and AFM imaging. Characteristic periodicity is determined and correlated with nanoparticle implantation dose, which permits us to tune the topographic pattern. Remarkable differences emerged with respect to the well-known case of wrinkling of bilayer metal-polymer. Wrinkled composite surfaces are characterized by a peculiar multiscale structuring that promises potential technological applications in the field of catalytic surfaces, sensors, biointerfaces, and optics, among others.

Conductive nanocomposite materials derived from SEBS-g-PPy and surface modified clay

Abstract Conductive nanocomposites were synthesized from surface modified clay and polypyrrole grafted triblock copolymer, polystyrene-b-poly(ethylene-co-butylene)-b-polystyrene (SEBS-g-PPy). The grafting of PPy was carried out on SEBS using FeCl 3 as an oxidant and the formation of subsequent materials was monitored by IR, 1 H NMR spectroscopy and Gel permeation chromatography (GPC). Surface treatment of the clay was carried out by ion exchange method using the cationic salt of 2,2-bis[4-(4-aminophenoxy)phenyl]propane for better adhesion with the polymer matrix. Thin composite films containing 1–8-wt.% organoclay were investigated by FTIR, XRD, TEM, tensile testing, TGA, DSC and electrical conductivity measurements. The molar mass as determined by GPC was around 37,000. XRD pattern and TEM images described good dispersion of clay platelets in the nanocomposites. Tensile testing revealed improvement in mechanical properties up to 3-wt.% of organoclay. The bulk electrical conductivity was increased up to 7-wt.% with increase in resonance of delocalized electrons of stretched PPy chains due to hydrogen bonding with organoclay in the nanocomposites. Thermal decomposition temperatures of the nanocomposites were in the range 435–448 °C. The decomposition of the nanocomposites was observed at higher temperatures relative to the pure polymer matrix with increasing clay loading. The weight retained after 900 °C was approximately equal to the amount of organoclay added in the composites. These composite materials exhibited improvement in glass transition temperature as compared to SEBS-g-PPy.

Electroactive actuation and conductive behavior of polyaniline-impregnated blood compatible nanocomposites

Novel electrically conducting and biocompatible composite hydrogel materials comprising polyaniline (PANI) nanoparticles dispersed in a polyvinyl alcohol—g—poly (2-acrylamido-2-methyl-1-propanesulfonic acid) matrix were prepared by in situ polymerization of aniline. The prepared ionic nanocomposites were evaluated for their water-uptake capacity in distilled water and electrolyte solutions. While structural confirmation and crystalline nature of the synthesized graft copolymer was sought by Fourier transform infrared spectroscopy and X-ray diffraction techniques, respectively, morphology and dimension of PANI particles embedded into the colored optically semi-transparent polymer films were evaluated by scanning electron microscopy analysis and transmission electron microscopy. Electrical conductivity of composite hydrogels containing different percentages of PANI was determined by the LCR meter while the electroactive behavior of composite hydrogel swollen in electrolyte solution was investigated by effective bend angle measurements. Considering the potential of electrically conductive nanocomposite materials in biomedical applications, the in vitro blood compatibility of nanocomposites was investigated by employing several established in vitro test procedures.

Enhanced corrosion protection coatings prepared from soluble electronically conductive polypyrrole‐clay nanocomposite materials

AbstractA series of electronically conductive nanocomposite materials that consisted of soluble polypyrrole (PPY) and layered montmorillonite (MMT) clay platelets were prepared by effectively dispersing the inorganic nanolayers of MMT clay in organic PPY matrix via an in situ oxidative polymerization with dodecylbenzene sulfonic acid (DBSA) as dopant. Organic pyrrole monomers were first intercalated into the interlayer regions of organophilic clay hosts and followed by a one‐step oxidative polymerization. The as‐synthesized electronically conductive polypyrrole–clay nanocomposite (PCN) materials were then characterized by Fourier transformation infrared (FTIR) spectroscopy, wide‐angle powder X‐ray diffraction (XRD), and transmission electron microscopy (TEM). PCNs in the form of coatings with low clay loading (e.g., 1.0 wt %) on cold‐rolled steel (CRS) were found to exhibit much better in corrosion protection over those of pristine PPY based on a series of electrochemical measurements including corrosion potential, polarization resistance, and corrosion current in 5 wt % aqueous NaCl electrolyte. Effects of the material composition on the thermal stability, optical properties, and electrical conductivity of pristine PPY along with PCN materials, in the form of fine powder, powder‐pressed pellet, and solution, were also studied by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), UV‐visible absorption spectra, and four‐point probe technique, respectively. The viscosity of PPY existed in PCN materials and pristine PPY were determined by viscometric analysis with m‐cresol as solvent. The heterogeneous nucleating effect of MMT clay platelets in PPY matrix was studied by wide‐angle powder XRD. The corresponding morphological images of the nucleating behavior of clay platelets in PPY matrix were investigated by scanning electron microscopy (SEM). © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 3264–3272, 2003