Functionalized Graphene Oxide Research Articles

Graphene Oxide, a Prominent Nanocarrier to Reduce the Toxicity of Alzheimer's Proteins: A Revolution in Treatment.

Graphene oxide, a derivative of graphene, has recently emerged as a promising nanomaterial in the biomedical field due to its unique properties. Its potential as a nanocarrier in the treatment of Alzheimer's disease represents a significant advancement. This abstract outlines a study focused on utilizing graphene oxide to reduce the toxicity of Alzheimer's proteins, marking a revolutionary approach in treatment strategies. The pathological features of Alzheimer's disease, primarily focusing on the accumulation and toxicity of amyloid-beta proteins, have been described in this review. These proteins are known to form plaques in the brain, leading to neuronal damage and the progression of Alzheimer's disease. The current therapeutic strategies and their limitations are briefly reviewed, highlighting the need for innovative approaches. Graphene oxide, with its high surface area, biocompatibility, and ability to cross the blood-brain barrier, is introduced as a novel nanocarrier. The methodology involves functionalizing graphene oxide sheets with specific ligands that target amyloid-beta proteins. This functionalization facilitates the binding and removal of these toxic proteins from the brain, potentially alleviating the symptoms of Alzheimer's disease. Preliminary findings indicate a significant reduction in amyloid-beta toxicity in neuronal cell cultures treated with graphene oxide nanocarriers. The study also explores the biocompatibility and safety profile of graphene oxide in biological systems, ensuring its suitability for clinical applications. It calls for further research and clinical trials to fully understand and harness the benefits of this nanotechnology, paving the way for a new era in neurodegenerative disease therapy.

Polyimide nanocomposites for high‐temperature capacitive energy storage applications by incorporating functional graphene oxide nanosheets: Design, preparation, and mechanism

AbstractHerein, graphene oxide (GO) and its derivative, reduced GO (rGO) and p‐phenylenediamine (PPD) functionalized GO (GO‐g‐PPD) were first synthesized and selected as dielectric fillers, and then GO/polyimide (PI), rGO/PI, and GO‐g‐PPD/PI dielectric nanocomposites were fabricated through in situ polymerization‐composition strategy. Fourier transform infrared, Ram, and x‐ray diffraction analysis confirmed the success synthesis of rGO and GO‐g‐PPD dielectric fillers. The mechanical properties showed that GO‐g‐PPD/PI nanocomposites exhibited the highest tensile strength and elasticity modulus. TGA analysis revealed that the enhancement of thermal stability by addition of dielectric fillers. The dielectric constant of 2.5 wt.% GO‐g‐PPD/PI nanocomposites reached 25.05, which was 8.55 times that of pure PI (2.93). Energy storage performance tests showed that the energy storage density of GO‐g‐PPD/PI containing 2 wt.% filler reached 0.77 J/cm3, which was 71% higher than pure PI. These findings underscore the potential of GO derivative as a cost‐effective reinforcement for PI dielectric nanocomposites for high‐temperature capacitive energy storage applications.

Polyvinylpyrrolidone‐functionalized graphene oxide as a nanocarrier for dual‐drug delivery of quercetin and curcumin against HeLa cancer cells

AbstractThis study is to develop a nanocarrier based on polyvinylpyrrolidone (PVP)‐functionalized graphene oxide (GO–PVP), loaded with both curcumin (CUR) and quercetin (QSR), and then its performance compared with nanocarriers carrying the drugs separately. The study also aimed to investigate the cytotoxic effects of these nanocarriers on HeLa cancer cells. To achieve this, GO was synthesized using a modified version of Hummer's method and subsequently functionalized with PVP. Drug loading onto the GO and GO–PVP nanocarriers was achieved through hydrophobic interactions. Furthermore, the ability of the nanocarriers to accommodate a single drug or a combination of drugs was examined. In our study, combined system shows higher drug loading, that is, 28.1% of QSR and 24.34% of CUR onto GO–PVP–QSR–CUR nanocarrier in comparison to single drug nanocarrier systems GO–PVP–QSR and GO–PVP–CUR which loaded 22.5% of QSR and 18.73% of CUR, respectively. Notably, the synthesized nanocarrier exhibited a pH‐sensitive drug release pattern. These results collectively suggest that GO–PVP–CUR–QSR displayed significantly higher cytotoxicity against HeLa cancer cells compared to both single‐drug nanocarrier systems at the specified concentrations. In addition, future pre‐clinical and clinical studies to evaluate the safety and efficacy of GO–PVP–CUR–QSR for cancer treatment are strongly recommended.Highlights Developed nanocarrier based on polyvinylpyrrolidone functionalized GO (GO–PVP). The GO–PVP nanocarrier was loaded with both curcumin (CUR) and quercetin (QSR). GO–PVP displays a higher loading capacity for both QSR and CUR compared to GO. QSR‐ and CUR‐loaded GO–PVP nanocarriers exhibited higher cytotoxic effects.

Functionalized Graphene Oxide as an Adsorbent Material for Endocrine Disruptor 4-Octylphenol

The widely used 4-octylphenol (OP) belongs to the group of endocrine disrupters (ED). However, it exerts potentially adverse effects on human health and the environment and has been detected in various environmental matrices. Adsorption is an effective treatment method for removing ED. This study analyzes the adsorption process of OP on graphene oxide (GO) on a bench scale and the central composite design was used for analyses of adsorption with four factors, namely, adsorbate concentration (100 to 120mg.L-1 COP), adsorbent concentration (0.2 to 3.4g.L-1 CGO), contact time (15 to 90min Ct), and pH (2 to 10). The results helped investigate adsorption capacity, adsorption kinetics pseudo-first order, pseudo-second order, Elovich equation, and intraparticle diffusion (IPD) and equilibrium conditions Langmuir, Freundlich, and Redlich-Peterson by mathematical models and showed 158.92mg.g-1 (120mg.L-1 COP, 0.2g.L-1 CGO, 90min Ct, and pH 2) maximum adsorption capacity. Regarding kinetics, Elovich equation best fitted the experimental data (R2 = 0.9961) and IPD indicated the adsorption process took place in the intraparticle and in the boundary layer. Redlich-Peterson model showed the best fit to the data (R2 = 0.9971) in the isotherms. The study demonstrated the adsorption of OP by GO in an aqueous solution can be used over a wide range of pH and contact times with no significant loss of efficiency.

Functionalized electrospun nanofibers to enhance β-Galactosidase immobilization and catalytic activity for efficient galactooligosaccharide synthesis

This study aimed to immobilize β-galactosidase (β-GAL) into enhanced polystyrene (PS) electrospun nanofiber membranes (ENMs) with functionalized graphene oxide (GO). Initially, GO sheets were functionalized by salinization with 3-aminopropyl triethoxysilane (APTES). Then the ENMs (PS, PS/GO, and PS/GO-APTES) were prepared and characterized. Then, the β-GAL was immobilized in the different ENMs to produce the β-GAL-bound nanocomposites (PS-GAL, PS/GO-GAL, and PS/GO-APTES-GAL). Immobilization of β-GAL into PS/GO-APTES significantly improved enzyme adsorption by up to 87 %. Also, PS/GO-APTES-GAL improved the enzyme activity, where the highest enzyme activity was obtained at enzyme concentrations of 4 mg/L, 50 °C, and pH 4.5. Likewise, the storage stability and reusability of immobilized β-GAL were improved. Furthermore, this process led to enhanced catalytic behavior and transgalactosylation efficiency, where GOS synthesis (72 %) and lactose conversion (81 %) increased significantly compared to the free enzyme. Overall, the immobilized β-GAL produced in this study showed potential as an effective biocatalyst in the food industry.

High-performance hybrid glass fibre epoxy composites reinforced with amine functionalised graphene oxide for structural applications

Glass fibre-reinforced epoxy (GFRE) composites have had limited use as structural components in industrial applications (e.g., oil and gas, aerospace and civil infrastructure). The use of nanomaterials, such as graphene, has been explored recently to enhance the mechanical and long-term properties of GFRE to realise their full potential and increase their usage. This study evaluated the tensile, creep, and fatigue behaviour of amine-functionalised graphene oxide (fGO) modified glass fibre/epoxy laminate composites. A spray coating technique was used to coat the fGO particles onto the glass fibre surface, and epoxy composite laminates were manufactured using the vacuum resin infusion method. Creep and fatigue testing were performed under a load-controlled mode in the tension direction. Adding fGO within the composites significantly improves the static, creep, and fatigue properties of the fGO-GFRE composites at both room and elevated temperatures. It is shown that adding fGO acts as a barrier to microcrack initiation and restrains the macrocrack propagation during cyclic loading under elevated temperatures in the GFRE composites. These factors, therefore, prevent the early delamination of the matrix and fibre interface during cyclic loading, which explains the fatigue life extension observed in the fGO-modified composites. With 0.05 wt% fGO, the fatigue life of the fGO-GFRE composites was extended by 8× and 30× at a maximum stress of 124–151 MPa, in a 90 °C environment compared to the control GFRE composites. While the creep life compared to the control increased by 63×, 103× and 159× with 0.25 wt%, 0.5 wt% and 1 wt% fGO, respectively. These enhancements are attributed to the large surface area, high stiffness, and functional groups present, which provide a stronger bond between the composite phases. These features help restrict the mobility of the polymer chain during the creeping load and act as barriers to fatigue crack propagation, enhancing the composite’s durability. The nanocomposites produced display attractive properties for many possible industrial applications where improved performance is needed while maintaining a minimum cost.

Formation and catalytic potential of sheet like nanostructured amino functionalized graphene oxide Schiff's base immobilized by Cu nanoparticles in Click reaction, oxidation of fluorene and in photodegradation of methylene blue

A heterogeneous catalyst, environmentally benign, containing copper immobilized over amino functionalized Schiff's base graphene oxide was prepared. The prepared nanocatalyst was explored in various organic transformations such as in tri-azoles formation, in oxidation and the degradation of methylene blue. Click chemistry was employed in the formation of triazoles for the construction of carbon-heteroatom bonds which have many applications ranging from drug discovery to material science. Our present work focused on graphene-based nanocatalyst (Cu @NH2GO) which provided excellent efficiency and catalytic activity in carrying out organic transformations. The prepared nanocatalyst was characterized and examined by various spectroscopic techniques such as X-ray diffraction (PXRD), thermo gravimetric analysis (TGA), field emission-scanning electron microscopy (FE-SEM), EDX, high-resolution transmission electron microscopy (HR-TEM), Fourier transformer infrared spectroscopy (FT-IR), and X-ray Photoelectron Spectroscopy (XPS). TEM images showed the light grey sheets of silane functionalized Schiff's base on which Cu nanoparticles were immobilized. The catalyst was also explored for the degradation of methylene blue which provided an effective path for the treatment of wastewater. Methylene Blue is one of the environmentally persistent, carcinogenic and mutagenic cationic dyes. A large volume of methylene blue containing wastewater is discharged into groundwater or surface water. So it becomes necessary to degrade the toxic dye by the use of a prepared nanocatalyst (Cu @NH2GO). Moreover, the catalyst possesses excellent stability and reusability.

Influence of the modification of chlorophyll-rich extracts on the hydrogen evolution reaction of rGO-based electrocatalysts

The great efforts to develop alternative electrocatalysts for efficient hydrogen evolution reaction (HER) applications through environmentally friendly synthesis still need to be completed. We explore a green route using spinach extract to simultaneously reduce and functionalize graphene oxide (GO). A spinach extract, rich in green reducing agents and chlorophyll, was obtained and modified by saponification and demetallation to yield Chln-H2 and further used to reduce and functionalize GO in a one-step procedure. The resulting RGO/Chln-H2 electrocatalyst was evaluated on the HER by Lineal Sweep Voltammetry (LSV), achieving a current density of −34.84 mA/cm2 starting its activation from an onset potential of −0.68 V vs reference hydrogen electrode (RHE). The effect of saponification and demetallation produces a new metal-free alternative catalyst with increased current density seven times, boosting hydrogen production performance.

Adsorption of Pb(II) and Cd(II) by functionalized graphene oxide (GO-MBT): Mechanisms, antibacterial activity, and DFT studies

Contamination of natural water with heavy metals is an ongoing environmental challenge and warrants the advancement of purification technologies. The present research deals with the synthesis and fabrication of graphite from coconut shell and subsequently to graphene oxide (GO) and thiol-functionalized GO-MBT adsorbents for the removal of heavy metals from aqueous medium. The synthesized GO and GO-MBT were characterized by employing HR-TEM, XPS, EDX, FTIR, FE-SEM, TGA, AAS and XRD. The adsorption kinetics followed the pseudo-second-order model with regression coefficients close to 1(0.99) for both Pb(II) and Cd(II). Thiol-functionalized GO-MBT showed the adsorption capacity of GO-MBT for Pb(II) and Cd(II) with a value of 116.959 mg/g at pH 6 and 112.99 mg/g at pH 7 respectively. The GO-MBT exhibited impressive adsorption efficiency towards heavy metal ions Pb(II) and Cd(II) owing to the presence of high density of oxygen and sulfur-containing groups. DFT calculations provide valuable insights into the structural and energy properties of GO and GO-MBT, supporting their stability and reactivity. Besides, the antibacterial activities of developed adsorbents were determined using the agar well diffusion method and broth dilution method. The developed GO-MBT could be used as an effective adsorbent for the removal of Pb(II) and Cd(II) and bacterial species from contaminated water.

Synthesis of Polyethylene Terephthalate (PET) with High Crystallization and Mechanical Properties via Functionalized Graphene Oxide as Nucleation Agent.

In this work, a novel functionalized graphene oxide nucleating agent (GITP) was successfully synthesized using a silane coupling agent (IPTES), and polymer block (ITP) to efficiently improve the crystallization and mechanical performance of PET. To comprehensively investigate the effect of functionalized GO on PET properties, PET/GITP nanocomposites were prepared by introducing GITP into the PET matrix using the melt blending method. The results indicate that PET/GITP exhibits better thermal stability and crystallization properties compared with pure PET, increasing the melting temperature from 244.1 °C to 257.1 °C as well as reducing its crystallization half-time from 595 s to 201 s. Moreover, the crystallization temperature of PET/GITP nanocomposites was increased from 185.1 °C to 207.5 °C and the tensile strength was increased from 50.69 MPa to 66.8 MPa. This study provides an effective strategy for functionalized GO as a nucleating agent with which to improve the crystalline and mechanical properties of PET polyester.

Sub-structures and phase transitions of bi-tilted smectic CG in dimer liquid crystals induced by amide functionalised graphene oxide

ABSTRACT A unique ferroelectric smectic CG phase, in its bi-tilting configurations induced by admixture of the dimeric liquid crystal (LC) 7OBA, serving as an matrix and amide functionalised graphene oxide (AmGO) was presented. Thus, an electrooptically tunable functionalised nanocomposite, indicating bi-tilting state, displayed by two sub-structures, CGcl (clinic) and CGln (leaning) was created. Using both microtextural and DSC analysis, we studied the thermal and structural features of the functionalised nanocomposite. By endothermal peak asymmetry analysis, we found an intermediate between CGcl and CGln state. An enhanced degrees of freedom of the LC director was indicated, allowing an increase of the corresponding micropolarisation LC textures able to create surface memorisation and reach information, respectively.

Mechanistic evaluation of contrasting modulation in conformation and catalytic performance of urease by surface interaction of graphene oxide and amine- functionalized graphene oxide nanosheets

The increasing use of graphene-based nanomaterials raises concerns about their potential environmental impact as ecotoxicants. This article examines the interaction and effects of graphene oxide (GO) and its amine-derived (GONH2) 2-D nanosheets on urease dynamics, a crucial enzyme in soil nutrient cycling, through spectroscopic, microscopic, and computational analyses. The findings reveal the distinct interaction mechanisms: GO formed ground - and excited-state complexes with urease; thus, fluorescence quenching was static and dynamic via hydrophobic interaction. In contrast, GONH2 nanosheets formed a ground-state complex by static quenching involving Van der Waals and hydrogen bonding. These interactions were energetically favored and altered tryptophan (Trp) residues’ microenvironment more than tyrosine (Tyr). The average exciton lifetime of urease in the presence of GO have decreased from 4.34 ns to 3.647 ns at the mere concentration of 7.11 µM, while for GONH2, no discernable change (4.16 ns) was observed even at the concentration of 16.75 µM. Primarily, the strong interaction of GO leads to the rearrangement of polypeptide structure, reduced α-helices to 12 %, and increased β-sheets by six times. In contrast, with GONH2, α-helices were reduced to 79 %, and β-sheets were increased by 1.8 times at the similar concentration. Molecular docking revealed that neither GO nor GONH2 interacted with the active site of urease, and binding was primarily via hydrophobic, Van der Waals, and hydrogen bonding, concurrent with in-vitro incubation results. Positive total energy (3.85 kJ mol−1) during molecular docking analysis of urease-GO interaction and inhibition in enzyme activity to 62 %, altered Vmax value (0.04606 ± 0.001 mM/s), without affecting the Km (4.78045 ± 0.12 mM) suggested that inhibition was noncompetitive and steric clashes due to disruptive binding might drove the inhibition. Meanwhile, negative total internal energy (-3.97 kJ mol−1) during urease + GONH2 binding and enhanced enzymatic activity by 32 % in-vitro without altering Vmax (0.063091 ± 0.003 mM/s) and Km (4.953943 ± 0.2 mM) values suggested that urease's binding site was well-complemented by GONH2 nanosheets, serving as a redox-mediator and radical-quencher.

Design of quetiapine fumarate loaded polyethylene glycol decorated graphene oxide nanosheets: Invitro-exvivo characterization

Quetiapine Fumarate (QF) is an atypical antipsychotic with poor oral bioavailability (9%) due to its low permeability and pH-dependent solubility. Therefore, this study aims to design QF-loaded polyethylene glycol (PEG) functionalized graphene oxide nanosheets (GON) for nasal delivery of QF. In brief, GO was synthesized using a modified Hummers process, followed by ultra-sonication to produce GON. Subsequently, PEG-functionalized GON was prepared using carbodiimide chemistry (PEG-GON). QF was then decorated onto the cage of PEG-GON using the π-π stacking phenomenon (QF@PEG-GON). The QF@PEG-GON nanocomposite underwent several spectral characterizations, in vitro drug release, mucoadhesion study, ex vivo diffusion study, etc. The surface morphology of QF@PEG-GON nanocomposite validates the cracked nature of the nanocomposite, whereas the diffractograms and thermogram of nanocomposite confirm the conversion of QF into an amorphous form with uniform distribution in PEG-GON. Moreover, an ex vivo study of PEG-GON demonstrates superior mucoadhesion capacity due to its surface functional groups and hydrophilicity. The percent drug loading content and percent entrapment efficiency of the nanocomposite were found to be 9.2±0.62% and 92.3±1.02%, respectively. The developed nanocomposite exhibited 43.82±1.65% drug release within 24h, with the Korsemeyer-Peppas model providing the best-fit release kinetics (R2: 0.8614). Here, the interlayer spacing of PEG-GON prevented prompt diffusion of the buffer, leading to a delayed release pattern. In conclusion, the anticipated QF@PEG-GON nanocomposite shows promise as a nanocarrier platform for nasal delivery of QF.

Photocatalytic bio‐inspired PDA‐RGO/g‐C3N4 nanocomposite incorporated PES membrane for removal of environmental antibiotic pollutants

AbstractBACKGROUNDMembrane technology makes it more suitable for the treatment of environmental polluted organic wastewater. Membrane fouling is one of the major concerns in commercial membranes. To overcome this issue, photocatalytic nanomaterials are embedded into the membrane to enhance its surface nature and reusability. In this investigation, polydopamine functionalized graphene oxide (PDA‐RGO), graphite carbon nitride (g‐C3N4) and PDA‐RGO/g‐C3N4 nanomaterials were incorporated within polyethersulfone membrane fabricated via a phase inversion technique. These as‐prepared membranes’ functional groups and surface morphologies were investigated by Fourier transform infrared (FTIR) spectroscopy, atomic force microscopy (AFM) and field emission electron microscopy (FESEM). These as‐prepared membranes were investigated for photocatalytic activity under visible‐light‐driven photodegradation by environmental pollutants such as Rhodamine B (RhB) and Norfloxacin (NOR).RESULTSCompared with pristine PES membrane, the PDA‐RGO/g‐C3N4‐PES nanocomposite membrane showed higher photocatalytic activity for Rhodamine B 94.6% and Norfloxacin 96.8%, also reached greater water flux 189 L m−2 h−1. Therefore, the bio‐inspired nanocomposite‐modified PDA‐RGO/g‐C3N4 photocatalytic membrane could have huge potential in processing environmentally polluted water.CONCLUSIONSPDA‐RGO/g‐C3N4‐PES nanocomposite membrane improved the membrane hydrophilicity, water flow, anti‐fouling performance, rejection studies and photocatalytic degradation than the pristine membrane. The synergistic result of PDA‐RGO and g‐C3N4 exhibits better photodegradation efficiency of the membrane towards environmental pollutants. © 2024 Society of Chemical Industry (SCI).

Amine functionalized graphene oxide decorated with ZnO-WO3 nanocomposites for remediation of organic dye from wastewater

Photocatalytic degradation is as an efficient technique to eradicate toxic chemical pollutants from contaminated water sources. However, the selectivity and photocatalytic activity are the challenging targets to explore the new photocatalysts. Therefore, our research goal is to develop a suitable photocatalyst to satisfy the recent photocatalytic degradation demand. In this work, amine functionalized graphene oxide (NH2-GO) supported heterojunction ternary novel nanocomposites (NH2-GO/ZnO-WO3) were prepared via simple solvothermal method. Structural and morphological investigations of the prepared composites are systematically observed by Field Emission Scanning Electron Spectroscopy (FE-SEM), X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FT-IR), and Ultraviolet–Visible (UV–vis) Spectroscopy. FT-IR analysis confirmed the effective functionalization of amine on graphene oxide. The XRD results indicated that the prepared nanocomposites were free from any impurities and the binary composite (NH2-GO/ZnO) showed hexagonal wurtzite structure, whereas the ternary composite (NH2-GO/ZnO-WO3) exhibited mix crystal structure of monoclinic and hexagonal phase of WO3 and ZnO, respectively. The synthesized ternary photocatalyst (NH2-GO/ZnO-WO3) demonstrated superior photocatalytic efficiency towards various organic dyes such as cationic dye methylene blue (MB, 85.89%) and anionic dye methyl orange (MO, 60.98%) compared to binary photocatalyst (NH2-GO/ZnO) that showed only 52.28% of MB and 25.8% of MO dye degradation under UV light irradiation. The enhanced photocatalytic performance was mainly due to the low recombination rate of photogenerated electron-hole pair, narrow band gap, and large surface area of ternary composite. The presence of lone pair electrons in amino group provides a negative-charged surface composite resulting good interaction with cationic dye is the key to upgrade the photocatalytic performance. The ternary nanocomposite NH2-GO/ZnO-WO3 has the capacity to be a competent and acceptable photocatalyst for the photodegradation of organic dyes used in industries.

Transport and retention of functionalized graphene oxide nanoparticles in saturated/unsaturated porous media: Effects of flow velocity, ionic strength and initial particle concentration

The widespread use of nanomaterials has raised the threat of nanoparticles (NPs) infection of soils and groundwater resources. This research aims to investigate three parameters including flow velocity, ionic strength (IS), and initial particle concentration effects on transport behavior and retention mechanism of functionalization form of graphene oxide with polyvinylpyrrolidone (GO-PVP). The transport of GO-PVP was investigated in a laboratory-scale study through saturated/unsaturated (Saturation Degree = 0.91) sand columns. Experiments were conducted on flow velocity from 1.20 to 2.04 cm min−1, initial particle concentration from 10 to 50 mg L−1, and IS of 5–20 mM. The retention of GO-PVP was best described using the one-site kinetic attachment model in HYDRUS-1D, which accounted for the time and depth-dependent retention. According to breakthrough curves (BTCs), the lower transport related to the rate of mass recovery of GO-PVP was obtained by decreasing flow velocity and initial particle concentration and increasing IS through the sand columns. Increasing IS could improve the GO-PVP retention (based on katt and Smax) in saturated/unsaturated media; katt increases from 2.81 × 10−3 to 3.54 × 10−3 s−1 and Smax increases from 0.37 to 0.42 mg g−1 in saturated/unsaturated conditions, respectively. Our findings showed that the increasing retention of GO-PVP through the sand column under unsaturated condition could be recommended for the reduction of nanoparticles danger of ecosystem exposure.

Experimental and theoretical investigation of high-performance supercapacitor based on guanidine functionalized graphene oxide

Functionalization of widely used graphene oxide (GO) can be beneficial not only in tuning its characteristics along with preventing the restacking of its layers and improving wettability but also in providing pseudocapacitance as a supercapacitor electrode. In this research, for the first time, the electrochemical performance of guanidine-functionalized graphene oxide (G-GO) examined by means of both computational and experimental methods. As a high-performance supercapacitor electrode, G-GO illustrates a high specific capacitance of 612F/g at the current density of 1.5 A/g together with extraordinary cyclic stability for 12,000 cycles at high current density of 10 A/g. Moreover, quantum capacitance together with the layer distance change during functionalization reaction, calculated via density functional theory (DFT), also exhibit the superior performance of G-GO.

Construction of anticorrosive coatings with emergency response closure by introducing functionalized graphene oxide

Vinyl ester resins (VER) are commonly used in the field of anticorrosive coatings. During the preparation and application of the coatings, it is inevitable to produce defects such as micro-porosity, micro-cracks, and scratches, which will reduce the barrier capacity of the anticorrosive coatings against corrosive media. In this paper, 2-(chloromethyl) pyridine is used to functionalize the silane-decorated graphene oxide for obtaining the functionalized modified graphene oxide (TGO). The aggregation of TGO nanosheets under the influence of Fe2+ ions generated by corrosion, achieving the response closure of TGO/VER coatings to hinder the diffusion path of corrosive media, thereby strengthening the anticorrosion effect of the coating. The water vapor transmission rate of TGO/VER coatings decreases significantly after immersion in Fe2+ solution. Electrochemical impedance spectroscopy tests indicate that TGO/VER coatings have better corrosion resistance compared with VER coatings, in which the impedance modulus after immersion for 100 d of 0.3TGO/VER coatings (3.93 × 1010 Ω cm2) is about four orders of magnitude greater than that of the VER coatings (5.85 × 106 Ω cm2). The TGO/VER coatings provide the responsive closure function via complexation of TGO with Fe2+ to achieve the long-term corrosion resistance. These results suggest that TGO/VER system provides an effective strategy for the preparation and application of graphene-based long-term anticorrosive coatings.

Self-healing thermally conductive polymer composites based on polyvinyl alcohol with dynamic borate ester and hydrogen bonds

Traditional thermally conductive polymer materials exhibit a propensity for damage when applied in dynamic environments, which leads to shortened service life and suboptimal utilization of resources. Herein, polyvinyl alcohol (PVA)-based thermally conductive composites with a self-healing capability are prepared based on dynamic borate ester bonds and hydrogen bonds. Poly(dopamine) functionalized graphene oxide (denoted as PGO) is used as a thermally conductive filler to achieve a high thermal conductivity (TC) of 0.79 W/(m·K) for the PGO/PVA composites, which is 527% of pure PVA (0.15 W/(m·K)). The improved TC of PGO/PVA composites is mainly attributed to the reduction in interface thermal resistance and the construction of heat conduction channels. Additionally, the PGO/PVA composites display a self-healing efficiency higher than 60% at room temperature without external simulation. Furthermore, the as-prepared PGO/PVA composites exhibit excellent mechanical properties, with a tensile strength of 409 kPa and an elongation at break of 479%, respectively. This work provides a promising strategy for fabricating thermally conductive polymer composites, which can be deployed as thermal interface materials for long-term applications.

Additive manufacturing of 3D networks based on poly(lactic acid) and amine functionalized graphene oxide as a platform for scaffolds

AbstractIn the present study, 3D networks were printed using the fused deposition modeling (FDM) technique. The purpose was investigate the printability of graphene oxide (GO)‐based composites for potential bone tissue engineering applications. Poly(lactic acid) (PLA) filaments containing GO and amine functionalized GO (N‐GO) were produced by melt extrusion and employed to print 3D networks. The cytotoxicity, morphological, rheological, and thermal behavior of the samples were compared. The morphological, rheological, and wettability analyses indicated an improvement in dispersion of GO throughout the matrix of PLA when GO was amine functionalized. The viscoelastic and flow properties, as determined by rheology, indicated that printed PLA samples containing freeze‐dried GO had lower viscosity than other composites, with a viscosity of 59.4 (Pa s), a decrease of nine times when compared with pure PLA, while the PLA containing N‐GO presented an improved viscoelastic interaction. PLA contact angle (108°) decreased by 87° and 84° for N‐GO and GO, respectively. The thermal analyses depicted that the incorporation of freeze‐dried GO and N‐GO had no effect on the crystallinity or thermal transitions of PLA matrix, maintaining its thermal stability. Finally, the cytotoxicity analysis indicated that the composites were not toxic throughout the cell culture assay and were found to promote cell viability, especially for the PLA/N‐GO network. Thus, these results revealed a vast horizon toward the use of GO/biodegradable polymers as platforms to print 3D networks to be applied as scaffolds.