Solution Intercalation Research Articles

Bottom-up stripping of graphene with controlled oxidation behaviors towards supercapacitors energy storage

Due to its distinctive two-dimensional planar structure, room temperature quantum Hall effect, and high strength, graphene has garnered significant interest in the fields of energy storage and conversion. In order to achieve high efficiency in the production of graphene, electrochemical peeling has been extensively investigated. Nevertheless, the intermolecular forces between graphite layers are disrupted during ion intercalation in solution, leading to inconsistent bonding forces and low yields. In order to address the issues above, this study introduces a novel bottom-up electrochemical peeling method, wherein graphite expansion occurs above the electrolyte. By preventing contact between the peeled graphene and the electrolyte, the oxidation of graphene is significantly minimized, resulting in a substantial yield of 88 %. At the current density of 1.0 A g−1, the Go-QAS displayed 225.5 F g−1, and kept about 220.2 F g−1 after 500 cycles. The well-designed bottom-up peeling process leads to graphene nanosheets with reduced structural degradation, high purity, and excellent conductivity. This technique is expected to introduce innovative concepts for the field.

Robust shape memory chlorobutyl rubber/boron nitride polymer nanocomposites for oil-water separation application

BackgroundBoron nitride (h-BN), an excellent 2D material finds exceptional applications in various fields owing to its unique characteristics including excellent hydrophobicity. Incorporation of boron nitride in polymer matrices is a captivating strategy by the scientific community to tune the properties of polymer. Interestingly, the possibilities of incorporating h-BN in chlorobutyl rubber (CIIR) matrix has never been considered and tried till now. Moreover, the use of CIIR to create a clean environment and reduce water pollution is an unexplored area even though the CIIR rubber possess excellent barrier properties. MethodsIn this work, two techniques were used for the fabrication of BNNS/CIIR nanocomposite. We exfoliated h-BN via chemical exfoliation method and tried the reinforcement of CIIR with BNNS via solution intercalation method. Shape memory analysis was performed with the help of stearic acid and oil-water separation analysis was achieved through an easy experimental technique. Significant findingsEnhanced mechanical strength of 11.57 MPa, improved thermal degradation temperature and char yield, higher glass transition temperature of -45.98° were observed for BNNS/CIIR nanocomposite reinforced with higher BNNS loading owing to the uniform distribution and better intercalation of BNNS in CIIR. Excellent shape memory was exhibited by CIIR matrix when reinforced up to 5 g BNNS. In addition, the nanocomposites displayed excellent ability to perform oil-water separation with increase in BNNS loading owing to the good hydrophobic character of h-BN and inherent barrier properties of CIIR. Thus, the study proved successful towards the fabrication of advanced CIIR nanocomposites with excellent shape memory and oil water separation efficiency.

Colorless and transparent polyimide nanocomposites using organically modified montmorillonite and mica

In this study, we introduce a method for replacing the glass used in existing display electronic materials, lighting, and solar cells by synthesizing a colorless and transparent polyimide (CPI) film with excellent mechanical properties and thermal stability using a combination of new monomers. Poly(amic acid) (PAA) was synthesized using dianhydride 4,4′-biphthalic anhydride (BPA) and diamine 2,2-bis(3-amino-4-hydroxyphenyl) hexafluoropropane (AHP). Various contents of organically modified montmorillonite (MMT) and mica were dispersed in PAA solution through solution intercalation, and then CPI hybrid films were prepared through multi-step thermal imidization. The organoclays synthesized to prepare CPI hybrid films were Cloisite 93A (CS-MMT) and hexadimethrine-mica (HM-Mica) based on MMT and mica, respectively. In particular, the diamine monomer AHP containing a –OH group was selected to increase the dispersibility and compatibility between the hydrophilic clays and the CPI matrix. To demonstrate the characteristics of CPI, the overall polymer structure was bent and a strong electron withdrawing –CF3 group was used as a substituent. The thermomechanical properties, morphology of clay dispersion, and optical transparency of the CPI hybrid films were investigated and compared according to the type and content of organoclays. Two types of organoclays, CS-MMT and HM-Mica, were dispersed in a CPI matrix at 1 to 7 wt%, respectively. In electron microscopy, most of the clays were uniformly dispersed in a plate-like shape of less than 20 nm at a certain critical content of the two types of organoclays, but agglomeration of the clays was observed when the content was higher than the critical content. Hybrids using HM-Mica had better thermomechanical properties and hybrids containing CS-MMT had better optical transparency.

Hierarchical antibiotic delivery system based on calcium phosphate cement/montmorillonite-gentamicin sulfate with drug release pathways

Antibiotic-loaded calcium phosphate cement (CPC) has emerged as a promising biomaterial for drug delivery in orthopedics. However, there are problems such as the burst release of antibiotics, low cumulative release ratio, inappropriate release cycle, inferior mechanical strength, and poor anti-collapse properties. In this research, montmorillonite-gentamicin (MMT-GS) was fabricated by solution intercalation method and served as the drug release pathways in CPC to avoid burst release of GS, achieving promoted cumulative release ratios and a release cycle matched the time of inflammatory response. The results indicated that the highest cumulative release ratio and release concentration of GS in CPC/MMT-GS was 94.1 ± 2.8 % and 1183.05 μg/mL, and the release cycle was up to 504 h. In addition, the hierarchical GS delivery system was divided into three stages, and the kinetics followed the Korsmeyer-Peppas model, the zero-order model, and the diffusion-dissolution model, respectively. Meanwhile, the compressive strength of CPC/MMT-GS was up to 51.33 ± 3.62 MPa. Antibacterial results demonstrated that CPC/MMT-GS exhibited excellent in vitro long-lasting antibacterial properties to E. coli and S. aureus. Furthermore, CPC/MMT-GS promoted osteoblast proliferation and exhibited excellent in vivo histocompatibility. Therefore, CPC/MMT-GS has favorable application prospects in the treatment of bone defects with bacterial infections and inflammatory reactions.

An overview on metal oxide incorporated bionanocomposites and their potential applications

Bionanocomposites - nanocomposites with a polymer of biological origin and one or more fillers - are an important class of materials that has gained the attention of researchers over the last few decades. Combining biopolymer with nano fillers improves strength and permeability and prevents nanofiller from corrosion. Different methods, such as in-situ polymerization, melt intercalation, template synthesis, solution intercalation are employed for the incorporation of nanomaterials (either 1D, 2D or 3D) to the biopolymer matrix. The properties of bionanocomposites depend highly on the nanoparticles that have been incorporated to make them suitable for a wide variety of applications. Both polymers and metal oxide nanoparticles have proved to be good candidates in applications such as antimicrobial, food packaging, automotive pharmaceutical, drug delivery etc. Inserting metal oxide nanoparticles to biopolymer matrices improves their permeability, mechanical strength, elasticity and thermal stability and increases their potentiality. Herein, the different bionanocomposites containing oxides of metals such as Ni, Zn, Al, Mg, Cu, Ti along with their applications are being discussed.

Preparation of Polyethylene Clay Composites via Melt Intercalation Using Hydrophobic and Superhydrophobic Organoclays and Comparison of Their Textural, Mechanical and Thermal Properties.

Polymer clay nanocomposites, which can exhibit many superior properties compared to virgin polymers, have gained increasing interest and importance in recent years. This study aimed to prepare composites of two organoclays with unusual ratios and different degrees of lyophilicity with low-density polyethylene and compare their textural structures and thermal and mechanical properties with those of virgin polymer. For this purpose, firstly, organoclays, hydrophobic and superhydrophobic organoclays (OC and SOC), were prepared by solution intercalation method using cetyltrimethylammonium bromide with and without addition of a hydrocarbon substance. Then, using both organoclays, polyethylene organoclay composites were prepared and characterized using X-ray powder diffraction (XRD), high-resolution transmission electron microscopy (HRTEM) and Fourier transform infrared spectroscopy (FTIR) techniques. Additionally, tensile and hardness tests were performed to determine the mechanical properties of the composites, and differential scanning calorimetry (DSC) thermograms were taken to examine their thermal behavior. XRD patterns and HRTEM images of hydrophobic and superhydrophobic organoclays and the composites show that the characteristic smectite peak of the clay shifts to the left and expands, that is, the interlayer space widens and, in the composites, it deforms immediately at low clay ratios. HRTEM images of the composites prepared especially with low clay ratios indicate that a heterogeneous dispersion of clay platelets occurs, indicating that nanocomposite formation has been achieved. On the contrary, in the composites prepared with high clay ratios, this dispersion behavior partially turns into aggregation. In the composites prepared using up to 20% by weight of superhydrophobic organoclay, extremely stable and continuous improvements in all mechanical properties were observed compared to those of the composites prepared using hydrophobic organoclay. This indicates that by using superhydrophobic organoclay, a ductile nanocomposite of polyethylene containing inorganic components in much higher than usual proportions can be prepared.

Effects of various types of organo-mica on the physical properties of polyimide nanocomposites

Poly(amic acid) (PAA) was synthesized using dianhydride 4,4’-oxydiphthalic anhydride and diamine 3,3'-dihydroxybenzidine, and polyimide (PI) hybrid films were synthesized by dispersing organo-mica in PAA through a solution intercalation method. Hexadimethrine-mica (HM-Mica), 1,2-dimethylhexadecylimidazolium-mica (MI-Mica), and didodecyldiphenylammonium-mica (DP-Mica), which were obtained via the organic modification of pristine mica, were used as the organo-micas for the PI hybrid films. The organo-mica content was varied from 0.5 to 3.0 wt% with respect to the PI matrix. The thermomechanical properties, morphology, and optical transparency of the resultant PI hybrid films were measured and compared. Dispersion of even small amounts of organo-mica effectively improved the physical properties of the PI hybrids, and maximum enhancements in physical properties were observed at a specific critical content. Electron microscopy of the hybrid films revealed that the organo-mica uniformly dispersed throughout the polymer matrix at the nanoscale level when added at low contents but aggregated in the matrix when added at levels above the critical content. Structural changes in the organo-mica closely influenced the changes in the physical properties of the hybrid films. All PI hybrid films with various organo-mica contents showed similar optical properties, but that prepared with MI-Mica demonstrated the best thermomechanical properties. All synthesized PI hybrid films were transparent regardless of the type and content of organo-mica used.

Effect of organoclay on the physical properties of colorless and transparent copoly(amide imide) nanocomposites.

Copoly(amic acid) was prepared using the diamine monomer N,N'-[2,2'-bis(trifluoromethyl)-4,4'-biphenylene]bis(4-aminobenzamide) (TFAB) and the anhydride monomers 4,4'-(hexafluoro-isopropylidene)diphthalic anhydride (6FDA) and 4,4'-biphthalic anhydride (BPA). Thereafter, a colorless and transparent copoly(amide imide) (Co-CPAI) film was synthesized through various heat treatments. Co-CPAI hybrid films with a TFAB : 6FDA : BPA molar ratio of 1 : 0.5 : 0.5 were subsequently fabricated using organically modified hectorite (STN) with various contents ranging from 0 to 7 wt% via the solution intercalation method. Finally, the thermomechanical properties, clay dispersion, and optical transmittance of the hybrid films were investigated. The results of wide-angle X-ray diffractometry and transmission electron microscopy demonstrated good dispersion at low clay loadings; however, clay agglomeration was observed above a certain critical STN content. At the critical STN content of 3 wt%, the clay was evenly distributed in the matrix with a nanoscale thickness of approximately 10 nm. Hybrid films containing 3 wt% STN showed excellent thermomechanical properties. Beyond this critical clay content, the physical properties of the films decreased because of the agglomeration of excess clay. Regardless of the clay content, however, the optical properties of the hybrid films remained constant, and their yellow indices, which ranged from 2 to 4, indicated excellent colorless transparency.

(Invited) Potentiometric Entropy Measurements and Isothermal Operando Calorimetry to Identify the Charging Mechanisms of Battery Materials

This talk presents recent development in potentiometric entropy measurements and isothermal operando calorimetry to gain insight into the charging mechanisms of lithium ion batteries. First, the concept, design, and operation of two unique experimental apparatuses will be presented. Then, the effects of material composition, crystallographic structure, and particle size on the cell’s thermodynamic behavior, polarization, and lithium ion transport will be discussed for different Wadsley-Roth materials (e.g., TiNb2O7, PNb9O25, (W0.2V0.8)3O7) under quasi-equilibrium conditions. Particular attention will be paid to phase transition, lithium ion intercalation and ion ordering in solid solution, and/or two-phase coexistence occurring during charging/discharging. Finally, instantaneous heat generation rates measured by isothermal operando calorimetry at each electrode will be used to identify the causes of energy dissipation and to provide insight into the transport and interfacial phenomena taking place in the electrodes at different states of charge and charging rates. Here, special emphasis will be placed on the contributions of Joule heating associated with resistive losses, heat of mixing due to ion concentration gradient, and reversible entropic changes.

Graphene nanoribbon doped PVA nanocomposites for improved UVC blocking and luminescence down‐shifting applications

AbstractGraphene nanoribbon (GNR) is quasi‐one dimensional carbon based nanomaterial, distinct from graphene and less explored nanofiller in optical and optoelectronic applications. Herein flexible poly vinyl alcohol (PVA) nanocomposites of 0, 0.25, 0.5 and 0.75 wt % compositions of GNR were prepared by using solution intercalation technique and characterized by spectroscopic methods to assess their structural and optical characteristics. The characterization of PVA@GNR nanocomposites revealed Vander Waals binding of GNR to PVA chains and also considerable crystallographic changes in PVA matrix upon the incorporation of GNR. The optical investigations showed UV‐visible absorption in the wavelength range of 200–280 and 350–520 nm which enhanced on increase in GNR dopant concentration. The decrease in the optical band gap and Urbach energy was also observed for the nanocomposites with increase in dopant concentrations thereby suggesting the formation of localized states in the forbidden band region. The refractive index, absorption coefficient, extinction coefficient and optical conductivity of PVA nanocomposites showed excellent agreement with the band gap revelations and indicated UVC light blocking properties in the wavelength of 200–280 nm. Further, the GNR incorporated PVA nanocomposites exhibited improved thermal stability, wettability transitions (hydrophilic to near hydrophilic) and excellent luminescent down‐conversion properties with a high Stokes's shift (100 nm) compared to pristine PVA nanocomposites. The study concludes that the proposed PVA@GNR nanocomposites can ideally fit optical and photovoltaic device applications owing to their transparency coupled with UV blocking and luminescence down‐shifting attributes.

High energy density electrodes based on solution intercalated, self-stabilised dispersion polymerised polyaniline/MWCNT hybrids for supercapacitors

Worldwide technological advancements have stimulated the need for efficient energy storage devices that can deliver high energy and power densities. This can be achieved by incorporating efficient electroactive materials like conducting polymers (CPs) and multi-walled carbon nanotubes (MWCNTs) and adopting different strategies for the preparation of electrodes. Hybrids of CPs with CNTs exhibit synergistic effects and are excellent choices as supercapacitor electrodes. In this work, polyaniline (PANI) is prepared using the self-stabilised dispersion polymerisation (SSDP) method. The PANI/MWCNT hybrid electrodes are prepared using the conventional in-situ method and a unique method that involves secondary doping followed by solution intercalation. The optimised electrode (PCM 1:1) displays a high specific capacitance of 1017 F g−1 at a current density of 0.5 A g−1. A symmetric supercapacitor fabricated using PCM 1:1 electrode delivers an energy density of 46.69 Wh kg−1 at a power density of 1 kW kg−1, one of the best reported values for similar composite materials. The device delivers an energy density of 27.86 Wh kg−1 even at a high-power density of 5 kW kg−1. The symmetric supercapacitor retains 93.3 % of its initial capacitance even after 10,000 continuous charge-discharge cycles at a current density of 5 A g−1. Interestingly, the electrodes and devices fabricated using the hybrid samples prepared by the solution intercalation method outperform those of the in-situ samples. The superior electrochemical performance, cycle stability and improved energy density of this hybrid sample offer ample scope for developing efficient and robust supercapacitors for futuristic energy storage devices.

Graphene nanoflake-self stabilized dispersion polymerized PANI hybrids as efficient, binder-free electrode materials for high-performance flexible symmetric supercapacitors

In this study, we prepared hybrid electrodes of self-stabilized dispersion polymerized (SSDP) polyaniline (PANI) and graphene nanoflakes by a facile solution intercalation approach. Unlike the conventional electrode preparation methods, the SSDP PANI dispersion was prepared by adopting the secondary doping method. The preparation of hybrid electrodes by a unique combination of these methods eliminates the use of binders and imparts excellent electrochemical properties to these electrodes due to synergistic effects. The optimized electrode (PG 2:1) demonstrates a specific capacitance of 454.9 F g−1 at a current density of 0.5 A g–1 and the symmetric supercapacitor using this electrode, achieved an energy density of 33.2 Wh kg−1 at a power density of 1 kW kg−1. Furthermore, even at a high-power density of 10 kW kg−1, the device delivers an energy density of 25.4 Wh kg−1. Interestingly, the symmetric supercapacitor retains 89.2 % of its initial capacitance even after 10,000 continuous charge–discharge cycles at a current density of 5 A g–1. The performance of these devices was also tested for different bending angles and was found to exhibit excellent stability. The superior performance of this hybrid electrode offers significant potential for the development of efficient binder-free flexible supercapacitors for portable and wearable devices.

Preparation of Melamine Formaldehyde Foam and a Melamine-Formaldehyde-Organo-Clay Nanocomposite and Hybrid Composites

Mineral fillers can be added to thermoset polymers to improve thermal conductivity and deformation behavior, shrinkage, impact strength, dimensional stability and molding cycle time. This study aims to prepare various hybrid composites (MFHCs) using melamine formaldehyde foam (MF), a melamine formaldehyde organo-clay nanocomposite (MFNC) and also pumice as primary filler, and gypsum, kaolinite and a hollow glass sphere as secondary filler. It also focuses on the study of some mechanical properties and thermal conductivities, as well as their microscopic and spectroscopic characterization. For this, firstly, organo-clay was prepared with the solution intercalation method using montmorillonite, a cationic surfactant and long-chain hydrocarbon material, and then was produced using a melamine formaldehyde nanocomposite with in situ synthesis using a melamine formaldehyde pre-polymer and organo-clay. Finally, hybrid composites were prepared by blending various minerals and the produced nanocomposite. For morphological and textural characterization, both FTIR spectroscopy and XRD spectra, as well as SEM and HRTEM images of the raw montmorillonite (MMT), organo-montmorillonite (OMMT), pure polymer (MF) and prepared hybrid composites, were used. Spectroscopic and microscopic analyses have shown that materials with different textural arrangements and properties are obtained depending on effective adhesion interactions between polymer–clay nanocomposite particles and filler grains. Mechanical and thermal conductivity test results showed that melamine-formaldehyde-organo-clay nanocomposite foam (MFCNC) exhibited a very good thermal insulation performance despite its weak mechanical strength (λ: 0.0640 W/m K). On the other hand, among hybrid composites, it has been determined that the hybrid composite containing hollow glass beads (MFCPHHC) is a material with superior properties in terms of thermal insulation and mechanical strength (λ: 0.642 W/m K, bulk density: 0.36 g/cm3, bending strength: 228.41 Mpa, modulus of elasticity: 2.22 Mpa and screw holding resistance: 3.59 N/mm2).

The synergistic effects of graphene on the physical, hydrophobic, surface, and thermal properties of acrylic-epoxy-polydimethylsiloxane composite coatings

Acrylic-epoxy based polydimethylsiloxane (PDMS) nanocomposite coatings loaded with different concentrations (0.5–3 wt%) of graphene nanoparticles were successfully prepared via solution intercalation approach. The main objective of this research was to investigate the hydrophobicity and thermal properties of the graphene-based coatings for various applications. Furthermore, the thermal analysis of the coatings was conducted via thermogravimetric analysis (TGA). In addition, the ultraviolet–visible (UV–Vis) spectroscopy and water contact angle (WCA) instrument were employed to evaluate the degree of transparency and surface wettability of the coatings. The surface adhesion analysis of the coatings was conducted using cross-hatch test (CHT) and the dispersion of the graphene nanoparticles was examined via field emission scanning electron microscope (FESEM) respectively. In terms of surface wettability, the graphene coating sample (1 % G) exhibited the highest WCA value of 99.75°, thus revealing its hydrophobic attribute. Moreover, the results obtained from TGA analysis revealed that the incorporation of graphene nanoparticles into the polymer matrix showed a reduction in degradation temperature, in other words, the increment of graphene content resulted the cross-linking density of the coating to decrease. Furthermore, at lower loading rates (e.g., 1 wt%), the FESEM results confirmed the excellent and even distribution of the graphene nanoparticles within the polymer matrix particularly at lower loading rates. At higher loading rates of graphene nanoparticles, the overall performance of the coatings was observed to decrease due to the presence of large agglomeration, which resulted the WCA to slightly decrease. In summary, due to its unique structure and properties, the incorporation of graphene as nanofiller into the polymer matrix could effectively enhance the compactness and protective performance of the acrylic-epoxy surface tolerant coating.

Advantages of a Solid Solution over Biphasic Intercalation for Vanadium-Based Polyanion Cathodes in Na-Ion Batteries.

The efficient operation of metal-ion batteries in harsh environments, such as at temperatures below -20 °C or at high charge/discharge rates required for EV applications, calls for a careful selection of electrode materials. In this study, we report advantages associated with the solid solution (de)intercalation over the two-phase (de)intercalation pathway and identify the main sources of performance limitations originating from the two mechanisms. To isolate the (de)intercalation pathway as the main variable, we focused on two cathode materials for Na-ion batteries: a recently developed KTiOPO4-type NaVPO4F and a well-studied Na3V2(PO4)2F3. These materials have the same elemental composition, operate within the same potential range, and demonstrate very close ionic diffusivities, yet follow different (de)intercalation routes. To avoid any interpretation uncertainties, we obtained these materials in the form of particles with merely identical morphology and size. A detailed electrochemical study revealed a much lower capacity and energy density retention for phase-transforming Na3V2(PO4)2F3 compared to NaVPO4F, which exhibits a single-phase behavior over a wide range of Na concentrations. The reasons for the inferior rate capability and temperature tolerance for the phase-separating Na3V2(PO4)2F3 material should be affiliated with slow phase boundary propagation. We hope that the comprehensive information on limiting factors provided for both mechanisms is useful for the further optimization of electrode materials toward a new generation of high-power and low-temperature metal-ion batteries.

Development of polyvinylpyrrolidone, inorganic nanoparticles, and lithium carbonate nanostructured systems

AbstractNanocomposites with inorganic nanofillers spread in a polymer matrix have been used for the development of pharmaceutical systems to treat mental illnesses such as bipolar disorder and Alzheimer's disease. In this study, nanostructured particles using a solution intercalation technique combined with a spray‐drying process using polyvinylpyrrolidone (PVP), montmorillonite, titanium dioxide, and lithium carbonate, with the aim of designing a new drug delivery system. XRD and low‐field nuclear magnetic resonance analyses showed that PVP/MMT 1% achieved an intercalated/exfoliated morphology. However, the incorporation of TiO2 nanoparticles into the PVP matrix did not affect its structure, indicating that there was not a strong interaction between the polymer and the TiO2 nanoparticles. Thermal analysis did not reveal any changes in the nanocomposites compared to the pure polymer. Scanning electron microscopy (SEM) analysis revealed a pseudo‐spherical shape, and SEM‐energy‐dispersive x‐ray spectrometry (EDS) confirmed the dispersion of MMT in the PVP matrix. The introduction of lithium carbonate into the PVP/MMT matrix created a new system with higher molecular mobility; the drug introduction increased the mean droplet size, and the zeta potential remained negative. Overall, the results indicate that the applied methodology can produce a new nanostructured particle as a drug delivery system.

Fabrication and characterization of graphene oxide-based polymer nanocomposite coatings, improved stability and hydrophobicity

In this study, acrylic-epoxy-based nanocomposite coatings loaded with different concentrations (0.5–3 wt.%) of graphene oxide (GO) nanoparticles were successfully prepared via the solution intercalation approach. The thermogravimetric analysis (TGA) revealed that the inclusion of GO nanoparticles into the polymer matrix increased the thermal stability of the coatings. The degree of transparency evaluated by the ultraviolet–visible (UV–Vis) spectroscopy showed that the lowest loading rate of GO (0.5 wt.%) had completely blocked the incoming irradiation, thus resulting in zero percent transmittance. Furthermore, the water contact angle (WCA) measurements revealed that the incorporation of GO nanoparticles and PDMS into the polymer matrix had remarkably enhanced the surface hydrophobicity, exhibiting the highest WCA of 87.55º. In addition, the cross-hatch test (CHT) showed that all the hybrid coatings exhibited excellent surface adhesion behaviour, receiving 4B and 5B ratings respectively. Moreover, the field emission scanning electron microscopy (FESEM) micrographs confirmed that the presence of the functional groups on the GO surface facilitated the chemical functionalization process, which led to excellent dispersibility. The GO composition up to 2 wt.% showed excellent dispersion and uniform distribution of the GO nanoparticles within the polymer matrix. Therefore, the unique features of graphene and its derivatives have emerged as a new class of nanofillers/inhibitors for corrosion protection applications.

Development of graphene incorporated acrylic-epoxy composite hybrid anti-corrosion coatings for corrosion protection

Corrosion-induced damages have resulted in malfunctions as well as failures in metallic structures and led to economical loss. In addition, the wonder material, graphene, is widely applied in the corrosion protection coatings due to its excellent chemical stability, superior mechanical properties, and high corrosion resistance. Herein, the remarkable features of graphene-based nanofillers to improve the barrier performance of the acrylic-epoxy based polymer coatings are demonstrated. In different weight percentages, graphene nanoflakes were added to the blended polymer coatings and the hybrid coatings were characterized using Fourier-transform infrared spectroscopy (FTIR), Contact angle (CA), Field emission scanning electron microscopy (FESEM) and Electrochemical impedance spectroscopy (EIS) to investigate the chemical structure, surface roughness, surface morphology and coating dispersibility and corrosion protection properties, respectively. All the coatings were prepared using solution intercalation technique (sonication process) to overcome the nanoparticle agglomeration. Furthermore, the obtained results suggested that incorporation of 1 wt% graphene remarkable improved the protective properties of the polymer coatings due to the excellent dispersion and even distribution of the graphene nanoparticles. Moreover, an increment of the CA was displayed with a decreasing trend in the water absorption rate particularly for 0.5–3 wt% loading rates of graphene nanoparticles within the polymeric matrix. At higher graphene concentrations, the large agglomeration led in the overall reduction of the corrosion resistance. However, at different immersion time, the FESEM micrographs revealed that a strong anticorrosion barrier was provided by the graphene nanofillers over a period of 90 days of immersion. Overall, due to the fascinating properties of graphene, the inclusion of graphene-based nanofillers in the polymer matrix enhanced the barrier and protective properties of the coatings.

Polycaprolactone-Modified Biochar Supported Nanoscale Zero-Valent Iron Coupling with Shewanella putrefaciens CN32 for 1,1,1-Trichloroethane Removal from Simulated Groundwater: Synthesis, Optimization, and Mechanism

1,1,1-Trichloroethane (1,1,1-TCA) is a typical organochloride solvent in groundwater that poses threats to human health and the environment due to its carcinogenesis and bioaccumulation. In this study, a novel composite with nanoscale zero-valent iron (nZVI) supported by polycaprolac-tone (PCL)-modified biochar (nZVI@PBC) was synthesized via solution intercalation and liquid-phase reduction to address the 1,1,1-TCA pollution problem in groundwater. The synergy effect and improvement mechanism of 1,1,1-TCA removal from simulated groundwater in the presence of nZVI@PBC coupling with Shewanella putrefaciens CN32 were investigated. The results were as follows: (1) The composite surface was rough and porous, and PCL and nZVI were loaded uniformly onto the biochar surface as micro-particles and nanoparticles, respectively; (2) the optimal mass ratio of PCL, biochar, and nZVI was 1:7:2, and the optimal composite dosage was 1.0% (w/v); (3) under the optimal conditions, nZVI@PBC + CN32 exhibited excellent removal performance for 1,1,1-TCA, with a removal rate of 82.98% within 360 h, while the maximum removal rate was only 41.44% in the nZVI + CN32 treatment; (4) the abundance of CN32 and the concentration of adsorbed Fe(II) in the nZVI@PBC + CN32 treatment were significantly higher than that in control treatments, while the total organic carbon (TOC) concentration first increased and then decreased during the culture process; (5) the major improvement mechanisms include the nZVI-mediated chemical reductive dechlorination and the CN32-mediated microbial dissimilatory iron reduction. In conclusion, the nZVI@PBC composite coupling with CN32 can be a potential technique to apply for 1,1,1-TCA removal in groundwater.

Nanocomposite of CO2-Based Polycarbonate Polyol with Highly Exfoliated Nanoclay.

Polypropylene carbonate (PPC) derived from carbon dioxide has been used as a precursor for the synthesis of polyurethane (PU). The high viscosity of the PPC is the key parameter hindering its processability during PU synthesis. Herein, a PPC nanocomposite with highly exfoliated nanoclay was prepared through a solution intercalation process. A wide range of nanoclay concentrations incorporated into the PPC were studied. The impacts of the nanoclay on the PPC were investigated in order to maintain the polymer structure while improving its physical properties. The characterizations of PPC nanocomposites showed that the highly exfoliated nanoclay contributed to a viscosity reduction, and a slight reduction in the molecular weight. The polymer degradation was indicated by the formation of cyclic propylene carbonate. The minimum or critical concentration of nanoclay was found to be between ∼0.5 and 2.0 wt %. Within this range, the polymer degradation is minimal. The PPC nanocomposites with a lower viscosity showed excellent precursors for making PU coating materials. The PU coating derived from the PPC nanocomposite has higher anticorrosive properties in comparison with the non-modified PU coating.