Graphene Oxide Nanofillers Research Articles

Sodium alginate- and chitosan-based hydrogels with different network charges for selective removal of cationic and anionic dyes from water

ABSTRACT The grafting of chitosan (CH) and sodium alginate (SA) biopolymers with glycidyl methacrylate (GMA) and acrylamide (AAm) monomers, combined with graphene oxide (GO), led to the formation of bio-based hydrogels. These hydrogels, named CH -GO -hydrogel (GO/CH-g-poly (AAm-co-GMA)), CH -GO -hydrogel (CH-g-poly (AAm-co-GMA)), SA -GO -hydrogel (GO/SA-g-poly(AAm-co-GMA)), and SA -hydrogel (SA-g-poly(AAm-co-GMA)), were tested as selective dye adsorbents. While the chitosan-based hydrogels exhibited positive zeta potential values ranging from +27.5 to +0.1 mV, alginate-based samples had negative values between −10.4 to −41.7 mV in pH conditions from 3.0 to 9.0. Adding GO nano-fillers reduced the swelling capacity of both hydrogels, with water absorption (WA) values for SA -GO -hydrogel and SA -hydrogel recorded at 10.1 and 22.2 g/g, respectively. The ability of these materials to adsorb dyes, specifically crystal violet (cationic) and Congo red (anionic), was confirmed. Factors such as adsorbent dosage, initial pH, dye concentration, shaking time, and temperature were analyzed to determine dye adsorption capacity. Interestingly, the pristine hydrogels, free of GO, performed better than their nanocomposite counterparts. Adsorption capacities (qm) for crystal violet and Congo red with SA -hydrogel, SA -GO -hydrogel, CH -hydrogel, and CH -GO -hydrogel was 909.1, 714.3, 454.5, and 400.0 mg/g, respectively.

Phytic acid-doped polypyrrole/graphene oxide nanofillers for the preparation of self-healing anticorrosion coatings with the synergistic physical barrier, passivation and chelating effect

The corrosion protection of organic coatings for metal substrates is generally limited because of the unavoidable coating micropores and cracks, even the coating anticorrosion function will lose when it is damaged. Although the addition of nanofillers into the organic coating matrix can effectively address the above issues, it is challenging to facilely and wholesale construct surface-modified nanofillers with synergistic anticorrosion ability of physical barrier, passivation and chelating effect. In this study, we develop a simple one-pot approach for preparing polypyrrole (PPy) modified graphene oxide (GO) nanofillers with the doping of phytic acid (Ph) (namely GO-PPy@Ph nanoparticles) and then incorporating them into epoxy resin (EP) coating system to form the anticorrosion nanocomposite coatings. The research results display that the GO-PPy@Ph nanoparticles can uniformly disperse in the EP coatings to improve their anti-penetrant ability against corrosive media. And the introduction of GO-PPy@Ph nanoparticles effectively enhances the coating adhesion strength and mechanical performance. Moreover, the anticorrosion tests show that the impedance modulus at 0.01 Hz of GO-PPy@Ph coating after 60-day immersion in 3.5 wt% NaCl solution remains at about 1010 Ω cm2. The dramatical anticorrosive performance of the GO-PPy@Ph coating with self-healing performance is attributed to the synergistic protection of impermeable GO-PPy@Ph nanosheets, passivation function of PPy and metal chelation effect of Ph. This study provides an effective and universal avenue to construct multifunctional nanofillers with the synergistic anticorrosion of high physical barrier, passivation and metal chelating effects for developing anticorrosive nanocomposite coatings with high performances, which have highly attractive potential in the commercialization applications of metal corrosion protection.

Graphene Oxide Nanosheets for Bone Tissue Regeneration.

Bone tissue engineering is a promising alternative to repair wounds caused by cellular or physical accidents that humans face daily. In this sense, the search for new graphene oxide (GO) nanofillers related to their degree of oxidation is born as an alternative bioactive component in forming new scaffolds. In the present study, three different GOs were synthesized with varying degrees of oxidation and studied chemically and tissue-wise. The oxidation degree was determined through infrared (FTIR), X-ray diffraction (XRD), X-ray photoelectron (XPS), and Raman spectroscopy (RS). The morphology of the samples was analyzed using scanning electron microscopy (SEM). The oxygen content was deeply described using the deconvolution of RS and XPS techniques. The latter represents the oxidation degree for each of the samples and the formation of new bonds promoted by the graphitization of the material. In the RS, two characteristic bands were observed according to the degree of oxidation and the degree of graphitization of the material represented in bands D and G with different relative intensities, suggesting that the samples have different crystallite sizes. This size was described using the Tuinstra-Koenig model, ranging between 18.7 and 25.1 nm. Finally, the bone neoformation observed in the cranial defects of critical size indicates that the F1 and F2 samples, besides being compatible and resorbable, acted as a bridge for bone healing through regeneration. This promoted healing by restoring bone and tissue structure without triggering a strong immune response.

Evaluation of a novel composite of expanded polystyrene with rGO and SEBS-g-MA.

This study displays the effect of reduced graphene oxide (rGO) nanofiller and polystyrene-b-poly(ethylene-ran-butylene)-b-polystyrene-grafted maleic anhydride (SEBS-g-MA) on the optical, thermal, and mechanical features of expanded polystyrene (EPS). First, the thin films of pristine EPS and composites were prepared using solution cast method. The prepared films were subjected to fourier-transform infrared (FTIR), SEM, UV-visible spectrophotometer, thermogravimetric analysis/differential scanning calorimetry, and universal testing machine for structural, morphological, optical, thermal, and mechanical characterizations. Optical study revealed a significant increase in refractive index and absorption of composites than EPS. Indirect band-gap energy of EPS (~4.08 eV) was reduced to ~1.61 eV for rGO composite and ~ 2.23 eV for composite composed of rGO and SEBS-g-MA. Thermal analyses presented improvement in characterization temperatures such as T10, T50, Tp, Tm, and Tg of composites, which ultimately lead to the thermal stability of prepared composites than pristine EPS. Stress-strain curves displayed higher yield strength (46.62 MPa), Young's modulus (96.29 MPa), and strain at break (0.54%) for EPS+rGO composite than pure EPS having stress at break (1.01 MPa), Young's modulus (12.44 MPa), and strain at break (0.08%). Moreover, ductility with relatively higher strain at break (0.61%) and lower Young's modulus (79.32 MPa) and yield strength (32.98 MPa) was noticed in EPS+rGO+SEBS-g-MA composite than EPS+rGO composite film. Morphological analysis revealed a change in globular morphology of EPS and inhomogeneous dispersion of rGO in EPS to homogeneously dispersed rGO in EPS matrix without globules owing to the addition of SEBS-g-MA. The increase in compatibility of EPS and rGO due to SEBS-g-MA was also observed in FTIR spectra. RESEARCH HIGHLIGHTS: Here, the solution casting approach was used to create the composite film of EPS and rGO with globules of various sizes. After adding SEBS-g-MA, the shape altered to globular free films exhibiting homogenous dispersion of rGO in EPS matrix. An optical investigation showed that composite materials had a significantly higher refractive index and absorption than EPS. The optical, thermal, and mechanical investigations suggest that the produced composites may be a great substitute for virgin EPS, allowing for a wider range of applications.

Effect of Graphene Oxide as an Anodizing Additive for the ZK60A Magnesium Alloy: Correlating Corrosion Resistance, Surface Chemistry and Film Morphology

The aim of the present work was to study the effect of graphene oxide as an additive in the anodization bath of the ZK60A magnesium alloy on the corrosion resistance, film morphology and surface chemical composition. The anodizing process was conducted at a constant current density of 30 mA.cm−2 in an electrolyte consisting of 3 M de KOH, 0.15 M de Na2SiO3 and 0.1 M Na2B4O7.10H2O. Graphene oxide was added to this bath at three different concentrations: 0.5 g.L−1, 1.0 g.L−1 and 3.0 g.L−1. The ability of the graphene oxide nanofiller to enhance the corrosion resistance of the ZK60A alloy was evaluated by electrochemical impedance spectroscopy and potentiodynamic polarization tests in 3.5 wt.% NaCl solution. The surface chemical composition was assessed by X-ray photoelectron spectroscopy (XPS). Scanning electron microscopy (SEM) coupled with EDS analysis was employed to examine the anodized layer morphology and thickness. The results pointed to a beneficial effect of graphene oxide addition on the corrosion resistance of the anodized ZK60A which was dependent on the concentration of the nanofiller in the anodizing electrolyte.

Design and development of graphene oxide/shape memory nanocomposite based on hexamethylene diisocyanate mixing segment

AbstractShape memory polymers are remarkable materials renowned for their distinctive ability to fix and recover their original shape in response to specific stimuli. However, the lower shape fixity (SF) of conventional thermally triggered shape memory polyurethane (SMPU) has limited its broad application potential. This study investigates the transformative influence of graphene oxide (GO) nanofillers when incorporated into a linear diisocyanate‐based mixing segment SMPU (SMPU‐GO). The lower SF issue of SMPU is ingeniously addressed by leveraging the interactive properties of GO with the 4,4′‐methylene bis‐phenyl diisocyanate hard segment and the introduction of additional physical cross‐links via hexamethylene diisocyanate mixing segment. At 1 wt.% GO incorporation, the modulus increased by 178%, an 8% increase in tensile strength, while the elasticity was maintained. Excellent improvement in SF and shape recovery (SR) was attained at 1 wt.% GO incorporated SMPU, and the SMPU nanocomposite showed the highest SF (65%) and SR (100%) at 70°C temperature and 50% strain.

PH-responsive P(AA-b-SBMA)-grafted magnetic GO high-performance ultrafiltration membrane with improved antifouling tendency and cleaning efficiency

Nanocomposite ultrafiltration polysulfone membrane with pH-responsive surface was designed and synthesized using poly (AA-b-SBMA)-grafted magnetic graphene oxide (MGP) nanofiller. The obtained membranes revealed advanced antifouling, high cleaning-efficiency, and high rejection when compared to pristine PSf membranes. The novel MGP nanofiller was synthesized by copolymerization of acrylic acid and sulfobetaine monomers on the grafted magnetic graphene oxide surface by RAFT polymerization. The non-solvent-induced phase separation was used to prepare polysulfone nanocomposite ultrafiltration membranes with pH-responsive surfaces optimized by the MGP content of 0.05 to 0.3 wt% in the dope solution. The MGP content embedded within the polysulfone matrix greatly influences the water flux. The optimal 144 LMH flux of water, achieved by 0.1 wt% MGP, was almost 80 % higher compared with the pure polysulfone. The optimal MGP-modified nanocomposite membrane showed high antifouling tendency and 72 % flux recovery value. Also, when pH changed from 3 to 8, the pH-responsive membrane revealed the best water flux recovery for bovine serum albumin adsorption-desorption. Comprehensive characterization of MGP nanofiller, the modified polysulfone, and pristine membranes confirmed that the surface hydrophilicity, cross-section morphology, surface roughness, and compositions of the modified ultrafiltration membranes could be modified considerably by the incorporation of MGP nanofiller.

Deciphering the role of 2D graphene oxide nanofillers in polymer membranes for vanadium redox flow batteries

This comprehensive review article explains the influence of various GO and GO-polymer membrane modifications for VRFB, which range from cation and anion exchange to amphoteric and zwitterionic membranes.

Optimizing the thermophysical qualities of innovative clay–rGO composite bricks for sustainable applications

This work concerned the development of a unique reduced graphene oxide (rGO) nano-filler to provide innovative opportunities in enhancing the thermophysical performance of clay composite bricks. Whereas, a series of clay–rGO composite bricks were produced, doped with various levels of rGO nanosheets (i.e., 0, 1, 2, 4, and 6 wt% clay). Each clay–rGO composite’s microstructure, shrinkage, morphology, density, porosity, and thermophysical characteristics were carefully investigated, and the thermal conductivity performance was optimized. Incorporation of different levels of rGO NPs to the clay matrix allowed all the peaks intensity to rise relative to the untreated one in the XRD pattern. Meanwhile, the inclusion of these doping resulted in a grew in the crystallite sizes and apparent porosity within the compositions. In this vein, shrinkage fracture of fabricated brick composites varied depending on dopants type and levels during the drying and firing processes. Moreover, there are some changes in chemical compositions, as well as wave shifts, suggesting that functional groups of rGO may have contributed to partially introduce carbonyl groups in clay–rGO composites. Besides, the porous topography and bulk density improved rapidly with respect to the plane of the rGO nanosheets within the composites. The differ-dense microstructure displayed in the SEM micrographs supports these outcomes. Remarkably, clay–(4%)rGO compound not only has an optimum thermal conductivity value (0.43 W/mK), but it also has a high heat capacity (1.94 MJ/m3K). These results revealed the exceptional features of rGO sheets such as large surface area with high porosity within the modified clay composites.

The Impact of Graphene Oxide Nano-fillers on the Bonding Strength and Delamination in Deep Drawing of FMLs

The Impact of Graphene Oxide Nano-fillers on the Bonding Strength and Delamination in Deep Drawing of FMLs

Enhancing the mechanical performance of E‐glass fiber epoxy composites using coal‐derived graphene oxide

AbstractIn this study, we compare the effect of various precursor‐based graphene oxide (GO) nanofillers on enhancing the mechanical performance of E‐glass fiber‐reinforced epoxy resin composites (EGFPs). GO derived from bituminous coal (BC‐GO) and graphite (Gr‐GO) were dispersed into an epoxy resin matrix. The resulting mixture was combined with E‐glass fiber mats using vacuum‐assisted resin infusion molding. Notable improvements (38.9% in flexural strength, 22.9% in tensile strength, and 21.6% in impact strength) were observed in BC‐GO‐reinforced EGFPs at 0.25 phr loading of BC‐GO. The improvements for Gr‐GO‐reinforced EGFPs were 28%, 9.3%, and 6.8%, respectively. XRD analysis of BC‐GO showed a diffraction peak at 2θ = 20.9°. Except for this peak, no other crystalline peaks were observed when BC‐GO was incorporated into EGFPs. FTIR spectra of both composite samples, with or without the nanofiller, were similar due to the spectral peaks overlap. TEM demonstrated the exfoliated morphology of BC‐GO in EGFPs. These findings underscore the potential of BC‐GO as a cost‐effective reinforcement for polymer nanocomposites across various industrial applications, including the development of lightweight and strong materials for aerospace and automotive industries, protective coatings, petroleum, and aerospace production systems.Highlights BC‐GO demonstrates superior mechanical performance compared to Gr‐GO in EGFPs. 0.25 phr BC‐GO improves 38.9% flexural, 22.9% tensile, and 21.6% impact strengths. Beyond 0.25 phr, BC‐GO and Gr‐GO showed a decline in mechanical enhancement. Role of particle size, loading & adhesion to matrix analyzed using XRD, FTIR, and DLS. Coal‐GO is an attractive alternative nanofiller for EGFPs.

Enhancement in proton conductivity and vanadium resistance of SPEEK-based hybrid membrane induced by incorporating amphoteric GO-DA nanofillers for vanadium flow battery

Sulfonated poly(ether ether ketone)-based hybrid membranes (S/GO-DA) have been fabricated through the solution-mixing method, and the introduced graphene oxide (GO) nanofillers functionalized by 2, 4-diaminobenesulfonic acid (DA) afford outstanding physicochemical properties and excellent battery performance for the S/GO-DA membranes. At low loading 1 wt% GO-DA nanofillers, the S/GO-DA-1 membrane gives the highest ion selectivity (45.4 × 103 S min cm−3) and the lowest vanadium ion permeability (7.38 × 10−7 cm2 min−1), which is superior to Nafion 212 (3.0 × 103 S min cm−3, 42.5 × 10−7 cm2 min−1) and SPEEK (3.85 × 103 S min cm−3, 94.4 × 10−7 cm2 min−1), respectively. Moreover, the better energy efficiency (81.1–68.6 %) and longer self-discharge time (78.3 h) of S/GO-DA-1 at 100–200 mA cm−2 current density further prove its good structure stability and durability, elucidating the balanced proton conductivity and vanadium resistance is helpful to enhance the membrane performance. In addition, after cycling at 150 mA cm−2 current density for at least 200 cycles, 76.3 % energy efficiency and 26.9 % charge retention rate are given, illustrating the combined physical barrier of GO-DA nanofillers and the acid-base interaction contribute a synergistic promoting effect on enhancing the battery efficiency of the S/GO-DA hybrid membranes. Therefore, the present work provides a facile method to construct a high-performance proton exchange membrane by developing 2D nanostructured nanofillers containing various chemical covalent-bonded functional amphoteric molecular chains.

Tunable optical and structural characteristics with improved electrical properties of (PVA-GO-CuO) eco-friendly-polymer nanocomposites and their DFT study

The research in this study have been motivated by the unique combination of GO (graphene oxide) and CuO nano-fillers with optimized composition in the poly vinyl alcohol (PVA) polymer. The (PVA-CuO-GO) polymer nanocomposites were created using a melt blending process with varying weight percentages of GO and CuO (ranging from 1 to 6 wt%) nanofillers. The composite was fashioned into a dumble-like structure. XRD (x-ray diffractometer), UV–Vis-NIR spectrophotometer, FESEM (field emission scanning electron microscope) and impedance analyzer were utilized to get the effect of nanofillers on the structural parameters, optical characteristics, surface morphology, and electrical properties of the composites. The influence of wt% of nano-fillers on crystalline size and micro-strain has been examined using XRD data. Tauc graphs were studied using UV–Vis-NIR spectrophotometer data for determining the direct and indirect optical bandgaps, and they show that increasing the weight percentage of nano-fillers causes the optical band gap (direct and indirect) to rise. The direct and indirect bandgap rose from 2.98 to 3.19 eV and 2.23 to 2.80, respectively, as the concentration of nano-fillers increased from 1 to 6 wt%. With increasing nanofillers amount, refractive index and Urbach energy were found to reduce; while peak extinction coefficient was found to increase. FESEM along with the EDAX analysis was also performed to investigate the smoothness of the composites' surfaces. Improvement in capacitance, dielectric constant and ac conductivity was also observed with increase in amount of nanofillers. DFT (Density functional theory) study has also been performed for Natural Bond Orbitals (NBO) analysis of charge and spin distribution, as well as HOMO, LUMO and molecular electrostatic potential (MEP). Based on the findings of the characterization results, the synthesized polymer nanocomposites can be employed in a variety of optoelectronics applications.

Advanced 3D printing of graphene oxide nanocomposites: A new initiator system for improved dispersion and mechanical performance

The integration of nanoparticles, such as Graphene Oxide (GO), with photo-curable polymers in 3D printing has garnered significant interest in recent years due to the potential to create functional nanocomposite materials. This study explores the challenges of achieving optimal dispersion of GO nanoparticles within the polymer matrix and the crucial role of photoinitiators in overcoming these limitations. Traditional photoinitiators, like TPO, commonly used for GO/polymer resins, have raised concerns about high toxicity and limited sensitivity to visible light, prompting the need for alternative initiating systems. In this research, we propose a two-component initiator system based on bis-(4-t-butylphenyl)iodonium hexafluorophosphate and photosensitizer N-{4-[(E)-2-(pentafluorophenyl)ethenyl]phenyl}-2,1,3-benzothiadiazol-4-amine (IOD/PS1) as a promising solution. This new initiating system not only ensures a more environment-friendly resin but also exhibits enhanced polymerization kinetics and compatibility with GO nano fillers. This study investigated the effect of the addition of nano-GO on the kinetics of the radical photopolymerization process, 3D printing, and final mechanical and thermal properties of the received products. TPO and PEGDA/H2O were used as reference systems. In addition, a new two-component initiator system was synthesized, which is an interesting alternative to the commercial TPO initiator that is widely employed in additive techniques. This publication presents the research procedure involving various techniques: real-time FTIR and photoreology. In addition, the possibility of creating three-dimensional structures from the newly developed photo-curable resins was verified. Finally, the morphologies and mechanical properties of the resulting 3D structures were compared. Within the work, we demonstrate the advantages of the two-component initiator in achieving uniform distribution of GO and fabricating high-quality materials. By applying IOD/PS1 initiating system we facilitated a more controlled and efficient polymerization process, reducing shrinkage-induced stresses and enhancing interlayer bonding. The result was the fabrication of high-quality, well-dispersed materials with tailored properties suitable for various applications, particularly in the biomedical field.

A long-term anti-corrosion and cathodic delamination resistant epoxy coating based on COF grafted GO nanofillers

Here, a long-term anti-corrosive epoxy (EP) coating based on nano-hybrid filler was developed. The surface of graphene oxide (GO) was aminated with (3-aminopropyl) triethoxysilane (APTES), and then the porous covalent organic framework (COF) was in-situ grown on amino functionalized graphene oxide (FGO) nanosheets by Schiff-based reaction to prepare FGO-COF nanofillers. Different characterization methods proved the successful modification of GO nanosheets with COF particles. The excellent water resistance of composite coatings was characterized through contact angle, adhesion, and water uptake tests. Transmission electron microscope (TEM) and molecular dynamics (MD) methods showed that the grafting of COF enhanced the dispersion and compatibility of GO in the coating. EIS measurements, salt spray analysis and cathodic delamination test indicated the significant improvements in the protective properties of the composite coatings compared with pure EP coating. The low-frequency impedance modulus of 1% FGO-COF composite coating reached higher than 6.8 × 109 Ω·cm2 after immersed in sea water for 60 days. In addition, the 1% FGO-COF composite coating performed only 34% delamination ratio after 120 h cathodic delamination test.

Kinetics and adsorption performance of biosorbent starch/poly(vinyl alcohol)/graphene oxide nanocomposite for the removal of dyes

The present work reports an efficient removal of a cationic dye, methylene blue (MB), and an anionic dye, methyl orange (MO) dye from an aqueous solution using graphene oxide (GO)–based nanocomposite as an adsorbent. GO was investigated as a potential nano-reinforcing filler in starch/poly(vinyl alcohol) (PVA) biopolymer matrix. Bio-nanocomposite based on starch/PVA matrix and GO were prepared by an aqueous casting method. The fabricated nanocomposites were characterized using FT-IR, XRD, Raman, TEM, FE-SEM, tensile study, Brunauer–Emmett–Teller (BET) method, Barrett–Joyner–Halenda (BJH) method, zeta potential, and swelling study. The effect of the various compositions of GO nanofiller in the starch/PVA matrix was highlighted and the impact of GO nanosheets on the properties of the nanocomposites was revealed. The results demonstrated that the starch/PVA matrix with 3 g of GO was found to be the optimal concentration of GO. Batch adsorption experiments were conducted to optimize the operational factors, including adsorbent dosage, pH, and contact time, which were systematically investigated. The kinetics of adsorption followed a pseudo-second-order model, while the Langmuir isotherm model described the equilibrium adsorption capacity. The prepared nanocomposite exhibited a maximum monolayer adsorption capacity of 382 mg g−1 for MB dye and 293.3 mg g−1 for MO dye. Based on the calculated thermodynamic parameters for the adsorption of MB (∆H° = − 16.37 kJ mol−1, ∆S° = − 37.99 J K−1 mol−1 and ∆G° from − 4.39 to − 5.13 kJ mol−1) and MO (∆H° = − 13.72 kJ mol−1, ∆S° = − 31.78 J K−1 mol−1 and ∆G° from − 3.72 to − 4.39 kJ mol−1) dyes onto the nanocomposite material was feasible, exothermic, and spontaneous. A plausible adsorption mechanism was proposed, involving electrostatic attraction, H-bonding, and π-π interactions, which collectively governed the adsorption process. The nanocomposite showed good stability and reusability up to five cycles for the uptake of MB and MO dyes. These findings confirmed the effectiveness of the proposed approach to produce bionanocomposite with enhanced properties, which may be used in water purification technology.

Synthesis and Characterization of Eco-friendly, Biodegradable Plasticized Starch Nanocomposite using Graphene Oxide Nano-filler for Energy Storage Applications

In this study, environment-friendly, biodegradable nanocomposite has been fabricated using plasticized starch (PS) polymer and graphene oxide (GO) nanofiller. Biodegradable PS has been extracted from potatoes and a solution casting technique was used to synthesize PS/GO nanocomposite. The structural and surface morphological properties of the nanocomposite have been studied via FTIR and FESEM which demonstrate increased degree of interaction between the PS matrix and the GO nanofiller. The thermal properties of the nanocomposite showed that incorporation of GO improves the thermal stability of the nanocomposites. To study the energy storage capabilities of the PS/GO nanocomposites the electrochemical properties of the nanocomposites were as studied through cyclic voltammetry (CV), and galvanostatic charge-discharge (GCD) methods. The PS/GO nanocomposite showed improved capacitive performance with a specific capacitance of 112 F/g compared to that of pure starch (2.20 F/g) at a current density 0.1 mA/cm2. To study the effect of GO on the electrochemical properties of the nanocomposites, electrochemical impedance spectroscopy was performed and the corresponding graphs were simulated using simulation software. The incorporation of GO reduces the charge transfer resistance and thereby improve the capacitive performance. The improved electrochemical performance of the PS/GO nanocomposite can be further attributed to the large surface areas provided by the GO sheets allowing faster transport of electrolyte ions into the electrode. The result indicates that the PS/GO and nanocomposites may offer a promising route for the synthesis of bio-friendly and flexible energy storage devices.
 J. of Sci. and Tech. Res. 4(1): 145-154, 2022

Molecular simulation investigations on the interaction properties of graphene oxide-reinforced polyurethane nanocomposite toward the improvement of mechanical properties

Thermoplastic polyurethanes (TPU) exhibit as multipurpose materials with diverse industrial applications. Meanwhile, owing to the brittleness and aging properties of neat TPU which severely limits its applications, the nanofillers were incorporated into the matrix to improve its physical properties. This can be attributed to the enriched interfacial interactions between the TPU moiety and the vastly reactive nanofiller hence the interpretation of interaction properties of the host-guest complex is highly constructive. Quantum mechanics-based molecular simulations was used to evaluate the structural, energetic, interaction nature, and mechanical properties of reinforced graphene oxide (GO) as potent nanofiller in the TPU matrix. Density functional theory-based calculations showed that TPU exhibited strong interaction with GO functional groups at the edge and on the surface, with interaction energies of − 35.303 and − 39.098 kcal/mol, respectively. The atominmolecule analysis indicated the existence of numerous hydrogen bonds between the GO nanofiller and TPU matrix in the nanocomposite. Reactive molecular dynamics simulations are used in the present study for the first time to examine the structural and mechanical properties of the TPU matrix and TPU/GO nanocomposite. Accuracy of reactive forcefield ReaxFF for physical and mechanical property estimations are validated against the reported experiments for the graphene system. It was found that the incorporation of GO (18 wt%) resulted in an increased Young’s modulus by about 34% (from 281 GPa for TPU to 378 GPa for TPU/GO). The charge analysis using the ReaxFF approach showed a significant charge transfer (3.483 e) from the TPU matrix to the GO skeleton. All these reveal the strong binding of GO to the TPU molecular chain in the nanocomposite, improving its physical and mechanical properties. Our comprehensive molecular simulations provide a well-grounded understanding of the interfacial interactions and mechanical properties of the nanofiller-reinforced polymer matrix. The present implemented computational methods and obtained results provide helpful information for the design and improvement of TPU/Graphene-based nanocomposites for potential applications in a new class of environmentally friendly shape memory materials.

Continuous extrusion foaming process of biodegradable nanocomposites based on poly(lactic acid)/carbonaceous nanoparticles with different geometric shapes: An insight into involved physical, chemical and rheological phenomena

AbstractOne‐step extrusion foaming process of biodegradable poly(lactic acid) (PLA)‐based nanocomposites in the presence of chemical foaming agent and chain extender has great complexity to control. In this work, PLA‐based nanocomposites containing different carbonaceous nanoparticles with different geometric shapes were obtained through a co‐rotating twin‐screw extrusion process to get insight into the dominant phenomena, which control the structural and final properties of PLA foams. The reactive extrusion foaming of PLA melt was investigated in the presence of carbon black, carbon nanotubes (CNTs), graphene oxide (GO), and a chain extender additive as well as a chemical foaming agent. Nanoparticles affect the continuous extrusion foaming of PLA melt through several phenomena, including providing bubble heterogeneous nucleation sites, intensifying the chemical decomposition of the foaming agent, improving the PLA structural modification reaction, increasing PLA molecular weight and restricting the dissolved gas removal from the melt. By influencing the involved phenomena in process, the nanoparticles at low levels, especially CNT and GO, increased the void content and cell size of PLA foams. The incorporation of CNT and GO nanofillers at the 0.5 phr level increased the electrical conductivity of PLA foams sharply by 9 and 10 orders of magnitude, resulting in lightweight, biodegradable semi‐conductive foams.

Biocompatible Poly(Vinyl Alcohol)-Copper Oxide-Graphene Oxide (PVA-CuO-GO) Nanocomposites: Synthesis, Structural and Optical Properties

Motivated by the unique combination of copper oxide (CuO) and GO (graphene oxide) nano-fillers with optimized composition in the PVA (poly vinyl alcohol) polymer, the studies in this paper have been directed towards the synthesis and characterization of (PVA-CuO-GO) polymer nanocomposites. The polymer nanocomposites, i.e., PVA-CuO-GO have been prepared by melt blending technique considering GO and CuO with variable wt.% (ranging from 0.5 to 3 wt.%). The composite was made in the shape of a dumble-like structure. To get the structural information, optical properties, surface morphology and available functional groups in the composites and their mechanisms, XRD (x-ray diffraction), UV-Vis-NIR spectrophotometer, photoluminescence (PL), FESEM (field emission scanning electron microscope) and FTIR (Fourier transform infrared) techniques have been used, respectively. From XRD data, the effect of wt.% of nano-fillers on crystalline size and micro-strain has been studied. The average crystalline size and micro-strain were calculated as ∼32 nm and ∼0.0250, respectively. From UV-Vis-NIR spectrophotometer data, tauc plots have been studied which tells that the increment in wt.% of nano-fillers causes the optical band gap to increase. On increasing the concentration of nano-fillers from 0.5 to 3 wt.%, the bandgap was increased from 2.5 to 2.8 eV. This tuning of bandgap can be supposed as fine tuning in near UV region. According to PL results, all the composites show a wide emission band in the UV-Vis region with the maximum at 487 nm when excited by 415 nm wavelength. Further, the luminescence intensity has been found to decrease with the addition of wt.% of the loading. The smoothness of the surfaces of the composites has also been studied with EDAX analysis. According to FTIR spectra, the available functional groups were found as: C–O, C–H stretch, C–H asymmetric stretch, C=O carbonyl stretch and C–H bending and deformation vibrations. In view of the characterizing results, the synthesized polymer nanocomposites can be used in several kinds of optoelectronics applications.