Functionalized Graphene Nanosheets Research Articles

Highly adsorptive removal of heavy metal, dye, and antibiotic pollutants using functionalized graphene nanosheets sono-electrochemically derived from graphitic waste

The development of highly adsorptive materials at low cost is critically important for efficient treatment of industrial wastewater. We herein report a one-step sonoelectrochemical strategy to synthesize functionalized graphene (FG) nanosheets as an effective adsorptive material using graphite waste from spent household batteries. Scanning/transmission electron and Raman microscopy studies reveal that the as-synthesized nanosheets are composed of few (2–6) graphene layers. Additionally, Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy analyses imply the presence of oxygen functional groups on the nanosheets (C=O and -COOH, oxygen content of 4.29%), which are immensely beneficial for the electrostatic adsorption with heavy metals, dyes, and antibiotics in aqueous solutions. As expected, FG nanosheets exhibit potent capabilities of handling a wide range of pollutants, such as methylene blue, methyl orange, enrofloxacin, and Pb2+, with high adsorption performances (99.95% and 21.21mg/g for Enrofloxacin, 98.93% and 119.3mg/g for methylene blue, 95.82% and 25.67mg/g for methyl orange, 95.56% and 86.10mg/g for Pb2+). These findings therefore show a great promise for practical uses of the FG material as efficient adsorbents in eliminating metallic, organic, and antibiotic pollutants in water.

Melt processing of graphene-coated polylactide granules for producing biodegradable nanocomposite with higher mechanical strength

ABSTRACT Innovative melt processing technology is necessary for the production of biodegradable polylactide/graphene nanocomposites. In this paper, we present the aqueous spray coating method to prepare graphene-coated polylactide granules for improving the distribution of small graphene contents in polymer matrix during the melt mixing process. Three types of functionalized graphene nanosheets, including graphene oxide (GO), reduced graphene oxide (RGO) and poly(ethylene glycol)/RGO (PEG/RGO), were investigated in the formations of graphene coatings on polylactide granules and subsequent melt-processed nanocomposites. It is found that RGO nanosheets have good interfacial compatibility to form better coatings on polylactide granules. Melt processing of graphene-coated granules produced polylactide/graphene nanocomposites with higher mechanical strengths. Nanocomposite materials containing 0.1% RGO showed the best improvements of mechanical and thermal properties. As-prepared nanomaterials and nanocomposites were characterized using transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), ultraviolet-visible spectroscopy (UV-Vis), attenuated total reflectance infrared spectroscopy (ATR-FTIR), tensile, flexural and impact measurements, differential scanning calorimetry (DSC) and integrated thermogravimetric analysis (TGA-DTA). In general, the innovative strategy of aqueous spray coating and melt processing is applicable for manufacturing biodegradable PLA/graphene nanocomposites in the sustainable trend of environmentally friendly development.

Simulation of adsorption behavior for various functionalized graphene nanosheets containing alkyl chain/polymer nanocomposites using ReaxFF

The non-covalent interactions in polymer/functionalized graphene nanosheet (FGN) nanocomposites containing the alkyl chain were investigated in this study. For this purpose, the non-covalent interactions at the interfaces of the mentioned polymer nanocomposites were accurately assessed using reactive molecular dynamics (RMD) simulation. The considered structures included poly(3-(4-n-octyl)-phenylthiophene) (POPT) and poly(3-phenylhydrazone thiophene) (PPHT) with FGNs featuring primary amine (PA), secondary amine (SA), alkanolamine (AA), and diamine (D) functional groups in alkyl chain. The functional groups varied in alkyl chain lengths via n (n equal to carbon atoms). Results from RMD simulations highlighted that the minimum interaction energy occurred between polymers and G-SA 1 %. PPHT exhibited strong interactions with G-D-4 1 % and G-PA-16 1 %. Contrary to other FGN, especially G-PA 1 %, increasing alkyl chain length in G-SA 1 % negatively affected polymers/G-SA 1 % interaction energy. Moreover, Hydrogen bonding (H-bonding) was examined in all different nanocomposites of PPHT/FGN. Also, the effect of an increase in coverage percentage and temperature was evaluated. These findings offer valuable insights into interactions of polymer-FGN with different alkyl chain lengths, aiding in the design of tailored nanocomposites.

Interfacial interaction energies at the interface of graphene/conductive polymer nanocomposites: A reactive molecular dynamics study

Reactive molecular dynamics (RMD) simulation was employed to investigate the interaction in the polymer nanocomposites, including functionalized graphene nanosheet (FGN) and conductive polymers namely poly (3-phenylhydrazone thiophene) (PPHT), poly (3-(4-n-octyl)-phenylthiophene) (POPT). FGN structures were resulted from incorporation of aryl functional groups containing various substitutions, including hydroxyl, ether. The effect of alkyl chain attached to hydroxyl was also examined. Based on the obtained results, the highest level of interaction energy was achieved in the PPHT/graphene-phenethyl alcohol (G-PhCH2CH2OH) and POPT/G-phenol (G-PhOH). The cause of the increase or decrease interaction energy in certain interaction in polymer nanocomposites was investigate by examining radial distribution function (RDF) diagrams in the case of different reactive sites. In addition, the polymer's state in terms of expansion or contraction during its interaction with FGN was determined based on radius of gyration (Rg) of the polymer. The impact of temperature variations among other parameters, was also examined. For this purpose, the nanocomposite of polymers/graphene-phenyl methyl ether (G-PhOCH3) was investigated at elevated temperature above 300 K. Ultimately, the investigation based on obtained RMD simulation results demonstrated a strong agreement with other reported other papers.

Effect of various aryl substitutions on the interfacial interaction energy of graphene/conductive polymer nanocomposites

Studying intermolecular interactions in polymer nanocomposites is highly effective in achieving high-efficiency nanocomposites. To investigate the polymer nanocomposites including conductive polymers, namely poly (3-phenylhydrazone thiophene) (PPHT), poly (3-(4-n-octyl)-phenylthiophene) (POPT), and functionalized graphene nanosheet (FGN), reactive molecular dynamics (RMD) simulation were employed. The FGN structures were a result of the arylation of graphene nanosheets containing different substitutions including sulfide, amine, di-amine, and thiol functional groups. According to interaction energies at polymers / arylated graphene nanosheet, the most interaction energies resulted in nanocomposites of PPHT/graphene-thiophenyl amine (G-PATP) and POPT/graphene-p-Phenylenediamine (G-PPD). Due to the polarity of PPHT, the formation of hydrogen bonding (H-bonding) was expected at specific sites, which were confirmed based on H-bonding interaction criteria. In reality, the criteria required for detecting H-bonding through RDF and the relevant angle measurement have been established. On the other hand, due to the acidic-sensitive hydrazone bond in PPHT, it was expected that the increasing trend in interaction energy of nanocomposites of PPHT could be solely justified based on the acidity of the functional groups employed. However, based on the obtained results, other factors such as the topological polar surface area (TPSA) and the formation of unconventional H-bonding, in addition to the acidity of functional groups, have been considered as influential factors in the changing of interaction energy. Also, the dynamic behavior of polymers was examined by plotting the radius of the gyration (Rg) parameter via time and functional groups. Finally, the temperature effect on interaction energy was determined, too.

Probing interaction of atherogenic lysophosphatidylcholine with functionalized graphene nanosheets: theoretical modelling and experimental validation.

The potential of graphene derivatives for theranostic applications depends on their compatibility with cellular and biomolecular components. Lysophosphatidylcholine (LPC), a lipid component present in oxidized low-density lipoproteins, microvesicles and free circulation in blood, plays a critical role in the pathophysiology of various diseases. Usingdensity functional theory-based methods, we systematically investigated the interaction of atherogenic LPC molecule with different derivatives of graphene, including pristine graphene, graphene with defect, N-doped graphene, amine-functionalized graphene, various graphene oxides and hydroxylated graphene oxides. We observed that the adsorption of LPC on graphene derivatives is highly selective based on the orientation of the functional groups of LPC interacting with the surface of the derivatives. Hydroxylated graphene oxide exhibited the strongest interaction with LPC with adsorption energy of - 2.1 eV due to the interaction between the hydroxyl group on graphene and the phosphate group of LPC. The presence of aqueous medium further enhanced this interaction indicating favourable adsorption of LPC and graphene oxide in biological systems. Such strong interaction leads to substantial change in the electronic structure of the LPC molecule, which results in the activation of this molecule. In contrast, amine-modified graphene showed the least interaction. These theoretical results are in line with our experimental fluorescence spectroscopic data of LPC/1-anilino-8-napthalene sulfonic acid complex. Our present comprehensive investigation employing both theoretical and experimental methods provides a deeper understanding of graphene-lipid interaction, which holds paramount importance in the design and fabrication of graphene-based nanomaterials for biomedical applications. In this study, we employed the density functional theory-based methods to investigate the electronic and structural properties of graphene derivatives and LPC molecule using the Quantum Espresso package. The exchange-correlation functional was described within generalized gradient approximation (GGA) as parameterized by Perdew, Burke and Ernzerhof (PBE). The valence electrons were represented using plane wave basis sets. `The Grimme's dispersion method was used to include the van der Waals dispersion correction.

Large-Area and Visible-Light-Driven Heterojunctions of In2O3/Graphene Built for ppb-Level Formaldehyde Detection at Room Temperature.

Achieving convenient and accurate detection of indoor ppb-level formaldehyde is an urgent requirement to ensure a healthy working and living environment for people. Herein, ultrasmall In2O3 nanorods and supramolecularly functionalized reduced graphene oxide are selected as hybrid components of visible-light-driven (VLD) heterojunctions to fabricate ppb-level formaldehyde (HCHO) gas sensors (named InAG sensors). Under 405 nm visible light illumination, the sensor exhibits an outstanding response toward ppb-level HCHO at room temperature, including the ultralow practical limit of detection (pLOD) of 5 ppb, high response (Ra/Rg = 2.4, 500 ppb), relatively short response/recovery time (119 s/179 s, 500 ppb), high selectivity, and long-term stability. The ultrasensitive room temperature HCHO-sensing property is derived from visible-light-driven and large-area heterojunctions between ultrasmall In2O3 nanorods and supramolecularly functionalized graphene nanosheets. The performance of the actual detection toward HCHO is evaluated in a 3 m3 test chamber, confirming the practicability and reliability of the InAG sensor. This work provides an effective strategy for the development of low-power-consumption ppb-level gas sensors.

Multiscale modeling of VOC–graphene nanostructure interactions: designing new sorbents for portable mass spectrometric applications

In this study, we conducted an extensive computational investigation using various theoretical approaches to elucidate the molecular-level interactions between ten representative volatile organic compounds and functionalized graphene nanosheets.

Ab – initio study on the stability and electronic property of graphene nanosheets: Applications to batteries

AbstractThe aim of this work is to improve the electrochemical performance of graphene nanosheets for its potential applications as electrode materials in supercapacitors. In order to achieve this, we have carried out detailed ab – initio based density functional theory calculations on pristine and functionalized graphene nanosheets (containing 8, 18, and 32 carbon atoms) with different functional groups. We considered graphene nanosheets functionalized with groups such as ether, lactone, ketone, and carboxylate in addition to previously studied epoxy and hydroxyl. From the structural optimization, we observed variations in the transverse displacement of carbon atoms, changes in CC and CO bond length, and bond angles. In particular, we noticed when functionalized with lactone CC and CO bonds contracts more which results in excessive surface charge density, and quantum capacitance, This suggest that C32 – functionalized with lactone would be a better candidate for battery electrodes with relatively high and values.

Edge and basal functionalized graphene oxide nanosheets: Two different behavior in improving electrical conductivity of epoxy nanocomposite coatings

Two different graphene nanosheets with different oxygen groups' localization were synthesized to investigate their effect on the electrical properties of graphene/epoxy nanocomposite coatings. Graphite natural flakes (NG) and expanded graphite (EG) were used as a carbon precursor to synthesize Edge functionalized (E-GO) and Basal Functionalized (B-GO) graphene nanosheets, respectively. Next, polymer nanocomposite coatings were fabricated by dispersing E-GO and B-GO into a waterborne epoxy matrix. Rheology was assisted in evaluating the dispersion state of the nanosheets in the epoxy matrix. B-GO exhibited better performance in network formation which can be related to the similarity of oxygen groups between B-GO and epoxy matrix. Next, the electrical conductivitie values of polymer nanocomposite coatings were measured after in-situ thermal reduction at 225 °C. The results indicated that polymeric coatings containing B-GO nanosheets represent higher electrical conductivity values compared to samples containing E-GO nanosheets despite the higher intrinsic electrical conductivity of E-GO compared to B-GO. This can be related to the improved ability of B-GO nanosheets to form an electrically conductive network inside the epoxy matrix. The electrical conductivity value of 0.5 S/m was obtained for polymeric coatings containing 0.8 vol% B-GO nanosheets with percolation thresholds of 0.17 vol%. The improved electrical conductivity can be correlated to the formation of the interphase region between the epoxy matrix and B-GO nanosheets which is the result of the similarity of the oxygen groups' nature in B-GO and epoxy.

Plasma treatment for enhanced functionalization of graphene nanosheets by octadecylamine

We report here a method for enhancing the non-oxygen functionalization of graphene nanosheets. This improvement is taken place by increasing the oxygen functional groups as the active reaction sites on graphene oxide by cold plasma treatment followed by substitution reaction by octadecylamine (ODA). The FTIR, XPS, XRD, RAMAN, and TGA analyses verified that the modification could increase the amount of functional groups by 61%. The plasma-treated functionalized graphene nanosheets were incorporated in polydimethylsiloxane (PDMS) membranes to remove toluene from water in pervaporation and showed an enhanced enrichment factor and pervaporation separation index of 123% and 68%, respectively, compared to those for the membrane incorporated with normally-functionalized reduced graphene nanosheets. The performance enhancement is attributed to the higher degree of functionalization of plasma-treated nanosheets, which causes a more uniform distribution of the nanosheets in the membrane acting as a barrier against water permeation while facilitating the permeation of toluene molecules through the membrane. Hence, this method could be used to increase the degree of functionality of graphenic materials and increase the applicability of these nanoparticles.

A Sensor for Selective Dopamine Determination Based on Overoxidized Poly‐1,5‐Diaminonaphthalene on Graphene Nanosheets

AbstractAn effective nanocomposite sensor for selective electroanalytical dopamine (DA) determination using overoxidized conducting polymer of poly‐1,5‐diaminonaphthalene (OPoly‐1,5‐DAN) functionalized graphene nanosheets (GNS) was achieved. The OPoly‐1,5‐DAN/GNS nanocomposite polymer was prepared via an electropolymerization of 1,5‐DAN on GNS/GCE after 7 cycles of potential scan (−0.2 V to +0.9 V), followed by an electrooveroxidation of the nanocomposite Poly‐1,5‐DAN/GNS by the potential cycle (0.0 V to +1.8 V) for 2 scans. The OPoly‐1,5‐DAN was effectively designed by GNS as a uniformly distribution of nanocomposite that caused more accumulations of analyte due to large electrocatalytic active positions created on electrode surface. The high specific and sensitive performance of the OPoly‐1,5‐DAN/GNS nanocomposite polymer was conducted to greater effective electrons transferring behavior for DA with copresent of vitamin C (VC). The stable and suitable formation of OPoly‐1,5‐DAN/GNS nanocomposite polymer showed rapid charge transport voltammogram and obvious electrocatalytic activity to DA and eliminated VC response. Moreover, the OPoly‐1,5‐DAN/GNS displays an excellent responses to DA determination with wide linear range (LR) 1.0–150 μM and lower detection limit (DL) 8.82±0.1 nM as comparing with other studies. Additionally, the excellent reproducibility of OPoly‐1,5‐DAN/GNS as well as long‐term stability indicated that it is an excellent and effective electrochemical DA sensor. Finally, the electroanalytical application of the OPoly‐1,5‐DAN/GNS nanocomposite polymer was employed for the electroanalysis of DA in human urine.

Functionalized graphene nanosheets obtained by direct shear exfoliation with poly(ionic liquid)s and its PAA composite

In this study, poly(ionic liquid)s functionalized graphene nanosheets (GNSPIL) were produced directly from graphite by shear exfoliation with the assistance of poly(ionic liquid)s. The chemical structure, as well as thermal, electrical, and mechanical properties of the obtained graphene sheets were characterized by TEM, SEM, AFM, FTIR, TGA, Raman spectroscopy, etc. In addition, a composite of graphene-coated sodium polyacrylate gel sphere (GNSPIL/PAA) was prepared by anion exchange reaction, and the properties of this composite were characterized through a series of techniques. This study showed that the obtained GNSPIL were well dispersed in water without agglomeration. Moreover, the solution-processability of GNSPIL and the easily realized ion exchangeability can greatly expand the application in the field of graphene composites and play an important role in the construction of carbon materials.

Biomass-Based Functionalized Graphene for Self-Rechargeable Zinc–Air Batteries

Commercial batteries are typically charged with electrical power systems and consume electrical energy for recharging. Chemically self-charging batteries are a class of electrochemical devices that use chemical reactions to recharge batteries without electrical grids. Herein, we report the fabrication of a self-rechargeable zinc–air battery that is capable of simultaneously harnessing and storing energy based on biomass-derived functionalized graphene nanosheets (f-GNS). The chemical energy was harnessed into electric power by the spontaneous and reversible redox reactions between the f-GNS and atmospheric oxygen. This enables the fabrication of an energy storage device capable of self-charging without using any catalyst or organic dye. For the realization of integrated energy harvesting, conversion, and storage by a facile and sustainable approach, the f-GNS synthesized by the hydrothermal carbonization of pears followed by mild acid oxidation was used as the active material in an alkaline solution. The self-rechargeable zinc–air battery delivered an initial open circuit voltage of ∼1.15 V and a maximum instantaneous peak power density of ∼250 mW cm–2. The zinc–air batteries can charge themselves at rest in 15 min and exhibit high reversibility and excellent durability over prolonged charge and discharge cycles. When connected in series and parallel, the zinc–air batteries can offer the desired voltage and current, respectively, for practical applications. This work opens an avenue for further advancement in the design of self-sustainable, next-generation aqueous zinc–air batteries for practical applications.

A theoretical investigation into the effects of functionalized graphene nanosheets on dimethyl sulfoxide separation

The potential of carbon-based nanosheet membranes with functionalized pores is great as water treatment membranes. Using the molecular dynamic simulation technique, the dimethyl sulfoxide (DMSO) separation from the water/DMSO binary solution is investigated, and the functionalized graphene nanosheets are used as a membrane. This membrane was functionalized by –F (fluorine) and –H (hydrogen) functional groups. For the separation of DMSO, external hydrostatic pressures up to 100 MPa were applied to the considered systems. The separation mechanism was based on molecular size. Multiple analyses were done to study the capability of considered membranes for the separation of DMSO molecules from water. The simulation results have indicated that the graphene membrane with various functional groups was impervious to DMSO molecules, and the water molecules were able to permeate across the membrane's pore with high penetrability. In this regard, the water permeability in 100 MPa was obtained at 3915.5 and 3715.3 L m−2. h−1. bar−1 for fluorinated and hydrogenated pore membranes, respectively. These functionalized graphene membranes have high efficiency, and they can be considered effective modules for water/DMSO binary mixture separations.

Biocompatible functionalized graphene nanosheet for delivery of doxorubicin to breast cancer cells

Nanotechnology has emerged as a promising approach to overcome the obstacles against successful cancer chemotherapy. Herein, biocompatible carbon nanosheets grafted with multi-cyclodextrin were fabricated for doxorubicin delivery to breast cancer cells. Structural characteristics of the nanocarrier were evaluated by FTIR, XRD, MAP, EDS, SEM, TEM, and VSM. Drug-loading and -encapsulation efficiencies were calculated to optimize the formulation. The biocompatibility of synthesized drug-carrier was determined using hemolysis assay and the MTT assay was performed to assess the viability of MCF-7 cells after treatment with various formulations. In-vitro drug release revealed the pH-triggered drug release capability of the drug carrier which can improve the cytotoxic potency of the doxorubicin in the tumor microenvironment. Hemolysis assay indicated the blood biocompatible feature of drug carrier which is further confirmed by cytotoxicity study, while, doxorubicin-loaded drug carrier significantly enhanced the cytotoxic effect of doxorubicin. Fluorescence microscopy observations of the nucleus after DAPI staining indicated the apoptotic-inducing effect of the drug-loaded carrier in comparison to free drug. This can be due to the higher internalization rate of drug-loaded carriers observed in fluorescence microscopy images. These results suggest that the fabricated drug carrier can be considered as a possible tool for the delivery of doxorubicin to breast cancer cells.

The simulation study of transport performance of HU drugs on functionalized graphene nanosheets based on the Density Functional Theory

In this study, density functional theory (DFT) was used to study the interaction between porous graphene nanosheets (PG), functionalized porous graphene nanosheets (PG-OH and PG-COOH) and HU anticancer drug, and to explore the effectiveness of functionalized porous graphene nanosheets as HU drug transport carrier. From the calculation results, it is found that HU drug tends to adsorb on the PG-COOH surface, and the existence of holes in nanosheets effectively improves the adsorption performance of graphene for HU drug. Non-covalent interaction (NCI) analysis showed that the interaction between HU drug and PG-COOH was mainly the result of double hydrogen bonds. Frontier molecular orbital analysis and density of state (DOS) analysis showed that the HOMO-LUMO energy gap of PG-COOH decreased with the adsorption of HU drug. In addition, the calculation results of adsorption energy and solvation energy show that the solvation of HU/PG-OH and HU/PG-COOH complexes in aqueous solvent is spontaneous, and the water molecules adsorbed on HU drug complexes can stabilize the structure. Overall, the calculations proposed that PG-COOH is more suitable for HU drug carrier in vivo. HU/PG-COOH complex has high stability in both gas phase and aqueous solution, which can achieve the purpose of sustainably releasing HU drug in vivo. These findings contribute to the development of new drug transport systems based on modified carboxy porous graphene for the transport of anticancer drugs.

New Fabricated (PAA-PVA/GO) and (PAAm-PVA/GO) Nanocomposites: Functional Groups and Graphene Nanosheets effect on the Morphology and Mechanical Properties

Graphene reinforcement brings high attraction from researchers as its sole properties improving the mechanical and structural properties of nanomaterials. The research aims to explore the effect of the functional group of the polymers have the same mainstay of the polymer chain but with a different end functional group in addition to the influence of graphene oxide (GO) nanosheets. Poly (acrylic acid) (PAA) and Poly (acrylamide) (PAAm) were the model polymer. These polymers mixed with Poly (vinyl alcohol) (PVA) separately after dissolved in distilled water (DW) then reinforced with GO applying the developed acoustic-sonication-casting method. The applying method was successfully fabricated the new nanocomposites from these mixed materials for the first time with a ratio of 4.5:4.5:1 wt. % of PAA: PVA: GO and PAAm: PVA: GO as nanocomposites, respectively. The new nanocomposites exhibited homogeneous combinations with an acceptable dispersal of GO in the polymers matrix as presented in the visual microscopy (OM). Coupled with the strong interplay between polymers in the matrix and the polymer with GO nanoparticles as nanocomposites, Fourier transform infrared (FTIR) verified the successful preparation of GO. Ultrasound measurements with a multi-frequency channel (30, 40 and 50 kHz) were used to characterize the ultrasonic velocity, absorption coefficient, compressibility and Bulk modulus, etc. Most of the mechanical properties were significantly improved of both new nanocomposites after the contribution of GO in comparison with blended polymers for both nanocomposites up to 74 %, 100 %, 198 and 177% respectively compared to their blended polymers. Interestingly, the PAA-PVA/GO nanocomposites presented a smoother surface and better mechanical results in comparison with PAAm-PVA/GO that showed rough surface and soften behaviour. The results of these new nanocomposites could aid in the development of promising materials for a variety of applications, such as improving oil recovery or developing medical and pharmaceutical applications.

Mechanical Robustness of Metal Nanocomposites Rendered by Graphene Functionalization.

Nanocarbon materials, such as graphene, carbon nanotubes, and their derivatives, are considered highly effective reinforcing agents in metals. Copious experimental and computational observations suggest that the nature of the interfaces may significantly affect the mechanical behavior of nanocarbon-metal composites, while the exact correlation between the interfacial structure and the deformation and failure mechanisms of the composite remains elusive. Using a nanolaminated graphene-aluminum (Al) composite as the model material, we designed and created composites with distinct interfacial structures and bonding states via graphene functionalization. The mechanical behavior of the composites was strongly affected by the structure of the functionalized graphene (FG)/Al interface, and the optimum strength-ductility synergy came from the composite with the intermediate extent of functionalization. Complementing experimental results with molecular dynamics and phase-field simulation efforts, we interpreted these results by the combined effects of the intrinsic strength of FG nanosheets and the FG/Al interfacial bonding state.

Fabrication and characterization of polyaniline functionalized graphene nanosheets (GNSs)/polydimethylsiloxane (PDMS) nanocomposite films

In this study, graphene nanosheets (GNSs)/poly(dimethylsiloxane) (PDMS) nanocomposites and the novel polyaniline (PANI)-functionalized graphene nanosheets (GNSs)/poly(dimethylsiloxane) (PDMS) nanocomposites were fabricated successfully. GNSs and PANI-functionalized GNSs were dispersed in PDMS matrix at different nanofiller concentration and nanocomposites were prepared via solution casting method. PANI functionalization were performed by in-situ polymerization of aniline in the presence of GNSs and was used in order to be dispersed homogenously and efficiently in the PDMS matrix. Besides graphene layers were also isolated to hinder aggregation in the polymeric matrix. The effect of PANI functionalization of GNSs and filler concentration on dielectric, electrical and mechanical properties of nanocomposite films were investigated. According to dielectric measurements, the dielectric constant of polymer nanocomposites highly dependant on frequency, so dielectric constant was characterized in a wide frequency range (1 Hz–10 MHz) at room temperature, in this study. The dielectric constant of PDMS nanocomposites containing 1.50% GNSs and 1.50% PANI-GNSs increased by 111 times and 24 times, at 1 Hz, compared to pure PDMS, respectively. Besides, electrical conductivity increased 6868 and 1474 times with the addition of GNSs and PANI-GNSs, respectively. Optimized GNSs/PDMS and PANI-functionalized GNSs/PDMS nanocomposites can be candidate for soft actuators to be used in artificial muscle applications, in the future.