Intercalation Polymerization Approach for Preparing Graphene/Polymer Composites

Polymer-Assisted Graphite Exfoliation: Advancing Nanostructure Preparation and Multifunctional Composites

Exfoliated graphite (ExG) embedded in a polymeric matrix represents an accessible, cost-effective, and sustainable method for generating nanosized graphite-based polymer composites with multifunctional properties. This review article analyzes diverse methods currently used to exfoliate graphite into graphite nanoplatelets, few-layer graphene, and polymer-assisted graphene. It also explores engineered methods for small-scale pilot production of polymer nanocomposites. It highlights the chemistry involved during the graphite intercalation and exfoliation process, particularly emphasizing the interfacial interactions related to steric repulsion forces, van der Waals forces, hydrogen bonds, π-π stacking, and covalent bonds. These interactions promote the dispersion and stabilization of the graphite derivative structures in polymeric matrices. Finally, it compares the enhanced properties of nanocomposites, such as increased thermal and electrical conductivity and electromagnetic interference (EMI) shielding applications, with those of neat polymer materials.

Aramid Nanofibers/Reduced Graphene Oxide Composite Electrodes with High Mechanical Properties

In this work, aramid nanofibers (ANFs)/reduced graphene oxide (ANFs/RGO) film electrodes were prepared by vacuum-assisted filtration, followed by hydroiodic acid reduction. Compared with thermal reduced ANFs/RGO, these as-prepared film electrodes exhibit a combination of mechanical and electrochemical properties with a tensile strength of 184.5 MPa and a volumetric specific capacitance of 134.4 F/cm³ at a current density of 0.125 mA/cm², respectively. In addition, the film electrodes also show a superior cycle life with 94.6% capacitance retention after 5000 cycles. This kind of free-standing film electrode may have huge potential for flexible energy-storage devices.

Mechanism for the Intercalation of Aniline Cations into the Interlayers of Graphite

The dynamic behaviors of aniline cation (ANI⁺) intercalating into graphite interlayers are systematically studied by experimental studies and multiscale simulations. The in situ intercalation polymerization designed by response surface methods implies the importance of ultrasonication for achieving the intercalation of ANI⁺. Molecular dynamics and quantum chemical simulations prove the adsorption of ANI⁺ onto graphite surfaces by cation–π electrostatic interactions, weakening the π–π interactions between graphene layers. The ultrasonication that follows breaks the hydrated ANI⁺ clusters into individual ANI⁺. Thus, the released positive charges of these dissociative cations and reduced steric hindrance significantly improve their intercalation ability. With the initial kinetic energy provided by ultrasonic field, the activated ANI⁺ are able to intercalate into the interlayer of graphite. This work demonstrates the intercalation behaviors of ANI⁺, which provides an opportunity for investigations regarding organic-molecule-intercalated graphite compounds.

pH-Induced Electrostatic Interaction between Polyacrylates and Amino-Functionalized Graphene Oxide on Stability and Coating Performances

Electrostatic interaction between polymers and nanofillers is of great importance for the properties and design of their composites. Polyacrylates with carboxyl, hydroxyl and acylamino groups were synthesized via emulsion polymerization and marked as P(MMA-BA-AA), P(MMA-BA-HEA) and P(MMA-BA-AM), respectively. Amino-functionalized graphene oxide (NGO) was prepared by Hoffman rearrangement using GO as the raw material. The polyacrylate composites were prepared by mixing NGO with each of the three kinds of polyacrylate. Effects of pH and NGO amounts on the properties of polyacrylate composites were studied. It was found that the surface charge of polyacrylate and NGO had the greatest effect on the composite properties. P(MMA-BA-AM)/NGO was not stable at any pH (2-8). With the same NGO amount of 0.1 wt%, the toughening effect of NGO on P(MMA-BA-AA) was larger than that on P(MMA-BA-HEA). The break strength of P(MMA-BA-AA)/NGO and P(MMA-BA-HEA)/NGO increased to 5.22 MPa by 47% and 3.08 MPa by 31%, respectively. NGO could increase the thermal stability of P(MMA-BA-AA) and P(MMA-BA-HEA) to different degrees. The polyacrylate film-forming processes were tested, and it showed that NGO influenced polyacrylate through the whole film-forming process. The results provide potential methods for the design of polymer-based nanocomposites.

Chitosan-Graphene Oxide Composite Membranes for Solid-Phase Extraction of Pesticides

Solid-phase extraction (SPE) coupled to LC/MS/MS analysis is a valid approach for the determination of organic micropollutants (OMPs) in liquid samples. To remove the greatest number of OMPs from environmental matrices, the development of innovative sorbent materials is crucial. Recently, much attention has been paid to inorganic nanosystems such as graphite-derived materials. Graphene oxide has been employed in water-purification processes, including the removal of several micropollutants such as dyes, flame retardants, or pharmaceutical products. Polysaccharides have also been widely used as convenient media for the dispersion of sorbent materials, thanks to their unique properties such as biodegradability, biocompatibility, nontoxicity, and low cost. In this work, chitosan-graphene oxide (CS_GO) composite membranes containing different amounts of GO were prepared and used as sorbents for the SPE of pesticides. To improve their dimensional stability in aqueous medium, the CS_GO membranes were surface crosslinked with glutaraldehyde. The composite systems were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis, swelling degree, contact angle, and mechanical measurements. As the GO content increased, a decrease in surface homogeneity, an improvement of mechanical properties, and a reduction of thermal stability of the CS-based membranes were observed. The increased dimensional stability in water, together with the presence of high GO amounts, made the prepared composite membranes more efficacious than the ones based just on CS in isolating and preconcentrating different hydrophilic/hydrophobic pollutants.

Two-Dimensional Nanomaterials-Based Polymer Composites: Fabrication and Energy Storage Applications

Polymers have been widely used for their low density, low cost, corrosion resistance, easy design, and processing. The addition of nanomaterials into polymer matrices has been studied for a long history due to their enhancement on properties of polymers, such as the electrical conductivity, thermal conductivity, corrosion resistance, and wear resistance. Two-dimensional materials, a new class of nanomaterials, have been intensively studied as a filler for polymer composites in recent years, which can significantly enhance the performance at even extremely small loading. In this review, firstly, the preparing and modifying method of 2D materials, such as graphene, graphene oxide, and hexagonal boron nitride, as a filler for polymer composites are organized. The related dispersion methods of 2D materials in the polymers, surface treatments of 2D materials, interface bonding between 2D materials and polymers are discussed alongside. Secondly, the applications of 2D materials/polymer composites for energy storage in lithium ion battery separators and supercapacitors are summarized. Finally, we have concluded the challenges in preparing 2D materials/polymer composites, and future perspectives for using this class of new composites have also been discussed.

Self-Cleaning Nanoscale Coating for the Separation of Oil–Water Mixture

The current study pertains to the self-cleaning nanoscale coating of graphene/polymer nanohybrid system for the separation of oil–water mixture. Using a single nanohybrid system, we have developed a two-stage process for the selective removal of the hydrocarbons. Total petroleum hydrocarbons (TPHs) and separation efficiency are determined by gas chromatography-flame ionization detector (GC-FID). Analysis of the polycyclic aromatic hydrocarbons (PAHs) in the two stage samples is carried out by using gas chromatography coupled to mass spectrometry (GC-MS). The analysis shows the reduction in TPHs from 290 ppm to less than 1 ppm and more than 99.5% separation efficiency (oil removal from oil–water mixture) is achieved. No polycyclic aromatic hydrocarbons (PAHs) were detected in the treated water.

Microflow Mechanism of Oil Displacement by Viscoelastic Hydrophobically Associating Water-Soluble Polymers in Enhanced Oil Recovery

Polymer flooding plays an important role in enhanced oil recovery (EOR), particularly in China, where partially hydrolyzed polyacrylamide (HPAM) and hydrophobically associating water-soluble polymers (HAWP) are used in onshore and offshore reservoirs, respectively. Many researchers have highlighted the elasticity of HPAM, which can be used to improve the sweep efficiency, i.e., the ratio of the area swept by an injected fluid to the oil area. On the other hand, fewer studies exist on the elasticity of HAWP. In this study, we investigate the flow of HAWP and Xanthan solutions with identical viscosities in core experiments in terms of elasticity; results reveal that the HAWP can produce shear thickening in the core. The constitutive equation for the HAWP can be obtained using the simulation results matched with the experimental data. On the basis of these experiments, we established a two-phase flow model of a polymer and oil, including the continuity, momentum, constitutive, and phase equations. The volume-of-fluid (VOF) method was used to track the interface between the two phases. A complex pore model was established based on the glass-etched model used in the experiment. We used the OpenFOAM platform to solve the mathematical model. The saturation, pressure, and stress tensor distributions were obtained. The results show that the displacement efficiency increased as the elasticity of the polymer increased; accordingly, the elasticity can enlarge the sweep area and decrease the residual oil saturation. As the elasticity increases, the stresses (the first normal stress, second normal stress, and shear stress) increase. Finally, the results obtained in this study can be used as a guideline in polymer design, screening, and optimization in the polymer flooding oilfields.