Synergistic effect of graphene and silicon dioxide hybrids through hydrogen bonding self-assembly in elastomer composites

A novel graphene–silicon dioxide hybrid (HGS) was prepared by plant polyphenol-tannic acid (TA) functionalized pristine graphene (G-TA) and primary amine-containing silane coupling agent modified SiO₂ (Si–NH₂). Through strong hydrogen-bonding interaction between the phenolic hydroxyl groups on G-TA and primary amine groups on Si–NH₂, SiO₂ was uniformly loaded to the surface of graphene. Due to the synergistic dispersion effect of graphene and SiO₂, which prevents restacking and re-aggregating of both graphene and SiO₂, HGS hybrids were distributed evenly in the natural rubber (NR) matrix (HGS@NR). Simultaneously, the surface roughness of graphene after loading SiO₂ and the interfacial interaction between the HGS hybrid and NR matrix were substantially improved. Due to the good dispersion and strong interface, the overall properties of HGS@NR nanocomposites are drastically enhanced compared with those of GS@NR nanocomposites prepared by dispersing the blend of unmodified graphene and SiO₂ (GS) in NR. The HGS@NR nanocomposites possess the highest tensile strength up to 27.8 MPa at 0.5 wt% and tear strength of 60.2 MPa at 0.5 wt%. Thermal conductivities of the HGS@NR nanocomposites were found to be 1.5-fold better than that of the GS@NR nanocomposites. Also, the HGS@NR nanocomposites exhibit excellent abrasive resistant capacity that is nearly 2-fold better than that of the GS@NR nanocomposites. These results suggest that HGS has great potential in high-performance nanocomposites and a new strategy of constructing the efficient graphene–SiO₂ hybrid fillers has been established.

A novel graphene–silicon dioxide hybrid (HGS) was prepared by plant polyphenol-tannic acid (TA) functionalized pristine graphene (G-TA) and primary amine-containing silane coupling agent modified SiO₂ (Si–NH₂).     

Energy-saving electrolytic γ-MnO2 generation: non-noble metal electrocatalyst gas diffusion electrode as cathode in acid solution

γ-MnO₂, which is commercially used as an electrode material in batteries, is produced using large amounts of energy and leads to the production of high pollution as a secondary product. Ideally, this material should be fabricated by energy efficient, non-polluting methods at a reasonable cost. This study reports the green fabrication of γ-MnO₂ into a gas diffusion electrode with Pt-free catalysts in acid solution. Cobalt oxide nanoparticles were deposited on few-layer graphene sheets produced via a simple sintering and ultrasonic mixing method, leading to the fabrication of cobalt oxide/few-layer graphene. Co₃O₄ nanoparticles are irregularly shaped and uniformly distributed on the surface of the few-layer graphene sheets. Characterization was conducted by X-ray diffraction, X-ray photoelectron spectroscopy, and field emission scanning electron microscopy. Electrochemical characterization revealed the performance of cobalt oxide/few-layer graphene gas diffusion electrode in an electrolyte of 120 g L⁻¹ manganese sulfate + 30 g L⁻¹ sulfuric acid at 100 A m⁻² at 80 °C. The cobalt oxide/few-layer graphene gas diffusion electrode exhibited a lower cell voltage of 0.9 V and higher electric energy savings of approximately 50% compared with traditional cathodes (copper and carbon).

Co₃O₄/FLG was used as a nanocatalyst to catalyze the ORR in the electrodeposition of MnO₂. The proposed Co₃O₄/FLG nanocomposite GDE exhibited a high activity of 0.9 V at a current density of 100 A m⁻².     

Fabrication of polyaniline–graphene/polystyrene nanocomposites for flexible gas sensors

This research work presents the fabrication of polyaniline (PANI) and graphene–polyaniline (graphene–PANI) nanocomposite-coated polystyrene (PS) nanofibre mats, as well as their application in flexible and highly sensitive gas sensors. The surface morphology of the flexible films is investigated using a number of techniques. The profilometry studies confirmed that the electrospun fibres are evenly distributed over a large surface area and there was no visible difference between coated and uncoated fibres. The SEM morphology studies revealed that a nanocomposite consisting of 10 nm PANI nanofibres and graphene forms a uniform coating around 3 μm diameter PS fiber. AFM showed differences in the 3D surface topography between plain PS nanofibres and coated ones, which showed an increased roughness. Moreover, conductive AFM has indicated an increase in the electrical current distribution from picoamperes to nanoamperes of the PS samples coated with PANI and graphene–PANI because of the applied voltage to the AFM tip that contacted the sample surface. The chemical properties of all the samples are analysed by Fourier transform infrared spectroscopy (FTIR) and X-ray powder diffraction (XRD), which revealed the presence of chemical interactions between the nanocomposites and the polymeric backbones. The TGA study indicated that graphene–PANI coated fibres have the highest thermal stability compared to the pure fibres. The addition of the nanocomposite layer to the PS fibre significantly increased the electrical conductivity. Therefore, nanocomposite-coated flexible membranes are used to fabricate carbon dioxide gas sensors (sensing range: 20–100 ppm). Due to the higher surface area of the nanocomposite coated fibre the availability of adsorption area is also higher, which leads to an increase in sensitivity to carbon dioxide gas. The sensitivity increases with the increase in gas concentration. The average response time of the sensor is calculated to be 65 seconds, with good and uniform repeatability.

A flexible thin membrane made of a graphene–PANI nanocomposite decorated PS electrospun fibre as a highly sensitive carbon dioxide gas sensor.     

Nanofiller-conjugated percolating conductive network modified polymerization reaction characteristics of aromatic thermosetting copolyester resin

Deliberately controlled interfacial interactions between incorporated nanofiller particles and host polymer backbone chains constitute a critical element in the realm of polymer nanocomposites with tailorable multifunctional properties. We demonstrate the physicochemical effects induced by graphene nanoplatelets (GNP) of different sizes on the condensation polymerization reaction of aromatic thermosetting copolyester (ATSP) through the formation of electrically conductive percolating networks as enabled by interfacial interactions. Carboxylic acid and acetoxy-capped precursor oligomers of ATSP are solid-state mixed with chemically pristine GNP particles at various loading levels. Upon in situ endothermic condensation polymerization reaction, crosslinked backbone of the ATSP foam matrix is formed while the carbonaceous nanofillers are incorporated into the polymer network via covalent conjugation with functional end-groups of the oligomers. The controlled GNP size promotes different electrical percolation thresholds and ultimate electrical conductivities. Microstructural analysis demonstrates GNP distributions in the matrix as well as morphological modifications induced by the formation of conductive percolating GNP networks. Cure characteristics reveal the thermochemical changes prompted in the polymerization processes for GNP content above the requirement for percolation formation. Chemical spectroscopy of the ATSP nanocomposite morphology exhibits the formation of a robust interfacial coupling mechanism between the GNPs and ATSP backbone. The findings here may guide the developmental efforts of nanocomposites through better identifying roles of the morphology and content of nanofillers in polymerization processes.

Physicochemical effects induced by graphene nanoplatelets on the in situ polycondensation reaction of aromatic thermosetting copolyester through the formation of conductive percolating network assembled via interfacial interactions.     

Fabrication of an antimony doped tin oxide–graphene nanocomposite for highly effective capacitive deionization of saline water

In this study, antimony doped tin oxide loaded reduced graphene oxide (ATO–RGO) nanocomposites were synthesized via a facile hydrothermal approach. As a typical N-type semiconductor, the ATO in the composite can enhance the conductivity between graphene sheets, thus improving the specific capacitance and electrosorption performance. Under the optimal conditions, the largest surface area was 445.2 m² g⁻¹ when the mass content of ATO in the nanocomposite was 20 wt%. The synthesized optimal ATO–RGO electrode displayed excellent specific capacity (158.2 F g⁻¹) and outstanding electrosorptive capacity (8.63 mg g⁻¹) in sodium chloride solution, which were much higher than the corresponding results of pristine graphene (74.3 F g⁻¹ and 3.98 mg g⁻¹). At the same applied voltage, electrosorption capacity and charge efficiency of the ATO–RGO (20 wt%) material were better than those of reported carbon materials in recent years.

Antimony doped tin oxide–graphene nanocomposites synthesized via a facile hydrothermal approach displayed good specific capacity and electrosorptive capacity.     

A graphene gold nanocomposite-based 5-FU drug and the enhancement of the MCF-7 cell line treatment

There is no doubt that cancer is now one of the most formidable diseases in the world; despite all the efforts and research, common treatment routes, including chemotherapy, photodynamic therapy, and photothermal therapy, suffer from different limitations in terms of their efficiency and performance. For this reason, different strategies are being explored to improve the efficiency of the traditional drugs reported to date. In this study, we have redirected the function of one of these drugs (5-fluorouracil, 5-FU) by combining it with a graphene–gold nanocomposite in different molar ratios that has been exceedingly used for biological research development. The high activity of the graphene–gold material enables it to produce reactive oxygen and ions, which display good anticancer and antioxidant activity through the scavenging of the DPPH, SOD and GP_x radicals; in addition, different characterizations have been used to confirm the structure and morphology of the obtained samples. Highly potent cytotoxicity against the MCF-7 cells was achieved with the drug combination containing the nanocomposite. All the results, including those obtained via cytometry, indicate that the combination of 5% graphene–gold nanocomposites with 5-FU exhibits a higher antitumor impact and more drug stability than pure 5-FU.

Graphene–gold nanocomposite materials combined with (5-fluorouracil, 5-FU) drug show high potent cytotoxicity against MCF-7 cells, can decrease HER-2 gene expression and cause cell cycle arrest.     

Electrochemistry of chemiluminescent novel hybrid nanocomposites based on polyaniline and hydrolyzed pectin with CdS nanoparticles

Novel hybrid nanocomposites based on polyaniline (PANi), hydrolyzed pectin (HPEc) and CdS nanoparticles (NPs) as electrochemiluminescent biomaterials were prepared. The samples were fabricated via heterogeneous chemical polymerization and studied by FTIR, XRD, SEM, EDX, UV/Vis, TGA and DMTA analyses. The CdS@HPEc-g-PANi nanocomposite was produced via in situ coprecipitation of CdS NPs by direct addition of aqueous cadmium nitrate and sodium sulfide solutions into the polymerization system containing PANi and HPEc. The mCdS@HPEc-g-PANi nanocomposite was synthesized via a new two-step surface modification strategy. The as-prepared CdS NPs synthesized via the chemical precipitation method were modified with epichlorohydrin as an organic reagent to obtain modified CdS (mCdS) and subsequently modified with HPEc and polymerized with aniline hydrochloride to produce mCdS@HPEc-g-PANi. The more smooth morphology of the mCdS@HPEc-g-PANi relative to the CdS@HPEc-g-PANi was approved by the SEM images. The cyclic voltammetry and electrochemical impedance spectroscopy analyses were performed on the samples to evaluate electrochemical properties and the results have indicated the reinforcing effect of the nanoparticles on the electrochemical properties of the nanocomposites. The electrical conductivity measurements by the four probe method have shown a significant increase of electrical conductivity in the presence of the CdS-nanoparticles. The CL experiments confirmed the chemiluminescence effect in the nanocomposites and also higher luminescence intensity for mCdS@HPEc-g-PANi relative to the CdS@HPEc-g-PANi nanocomposite owing to better dispersion of CdS NPs in the former sample.

The mCdS NPs due to uniform dispersion improved the conductivity, electrochemical and chemiluminescence properties in mCdS@HPEc-g-PANi.     

Effects of bleaching and functionalization of kaolinite on the mechanical and thermal properties of polyamide 6 nanocomposites

Polyamide 6 nanocomposites (PA6)/kaolinite were prepared by melt compounding. First, kaolinite was bleached via a solvothermal reaction using oxalic acid as a bleaching agent; then, the bleached product was modified using dimethylsulfoxide (DMSO) and subsequently methanol (MeOH) via a displacement method. Thus, cetyltrimethyl ammonium bromide (CTAB) and triethoxy(octyl)silane (TEOS) molecules were intercalated into kaolinite nano-platelets. Seven types of nanocomposites were prepared using pristine, bleached or intercalated kaolinite. The kaolinite powder and the nanocomposite specimens were characterized by X-ray diffraction (XRD), Fourier transformation infrared spectroscopy (FTIR), thermal analysis, scanning electronic microscopy (SEM), whiteness index and tensile tests. The influence of the bleaching process of kaolinite and the intercalation methods on the whiteness index of the nanocomposites was also observed, in which the whiteness index of the functionalized kaolinite nanocomposites was enhanced by up to 10.65% when compared to neat PA6. The thermal results revealed that the intercalation and functionalization greatly affect the thermal stability of the virgin polymer. On the other hand, the intercalation of kaolinite enhances the dispersion/distribution, improves the interfacial adhesion, and increases the aspect ratio of the kaolinite nanoparticles; this affords remarkable nanocomposite property enhancements, represented by a high Young''s modulus value of 4.68 GPa and a maximum percentage growth of 80.6% for silane-grafted kaolinite nanoparticles at just 8 wt%.

This study presents the effects of bleaching and functionalization of kaolinite on the mechanical and thermal properties and whiteness index of polyamide 6 nanocomposites prepared by melting compounding.     

Enhanced thermal conductivity of nanocomposites with MOF-derived encapsulated magnetic oriented carbon nanotube-grafted graphene polyhedra

It remains a challenge to develop highly polymer-based nanocomposite thermal interface materials, which can effectively remove heat developed during the miniaturization of electronic instruments. It has been reported that a large number of graphene-based nanocomposites exhibit excellent performance. However, it is still an issue to construct thermal conductive pathways by orientation arrangements with a low filler volume fraction. Herein, a high-thermal conductivity filler of magnetic carbon nanotube-grafted graphene polyhedra (Co@Co₃O₄-G) was exploited via the annealing of metal–organic frameworks (ZIF-67). Co@Co₃O₄-G can improve the thermal conductivity of nanocomposites obviously by forming oriented pathways for phonon transport in an external magnetic field. Therefore, the resulting nanocomposite displayed a high thermal conductivity of 2.11 W m⁻¹ K⁻¹ for only 8.7 vol%, which is 10 times higher than that of the pure epoxy resin. Core-shell magnetic cobalt oxide (Co@Co₃O₄) was encapsulated in situ in the nanoarchitecture to avoid falling off. Moreover, the equilibrium molecular dynamics (EMD) simulation verifies that Co@Co₃O₄-G had high thermal conductivity to effectively improve the heat dissipation of nanocomposites. This strategy provides an approach for developing high-performance thermal management materials and opens up the possibility for the pioneering applications of encapsulated magnetic-oriented thermal conductive fillers.

A high-thermal conductivity filler of magnetic carbon nanotube-grafted graphene polyhedra is exploited via annealing of a metal–organic framework (ZIF-67).     

In situ synthesis of copper nanoparticles encapsulated by nitrogen-doped graphene at room temperature via solution plasma

Metal–carbon core–shell nanostructures have gained research interest due to their better performances in not only stability but also other properties, such as catalytic, optical, and electrical properties. However, they are limited by complicated synthesis approaches. Therefore, the development of a simple method for the synthesis of metal–carbon core–shell nanostructures is of great significance. In this work, a novel Cu–core encapsulated by a N-doped few-layer graphene shell was successfully synthesized in a one-pot in-liquid plasma discharge, so-called solution plasma (SP), to our knowledge for the first time. The synthesis was conducted at room temperature and atmospheric pressure by using a pair of copper electrodes submerged in a DMF solution as the precursor. The core–shell structure of the obtained products was confirmed by HR-TEM, while further insight information was explained from the results of XRD, Raman, and XPS measurements. The obtained Cu-core encapsulated by the N-doped few-layer graphene shell demonstrated relatively high stability in acid media, compared to the commercial bare Cu particles. Moreover, the stability was found to depend on the thickness of the N-doped few-layer graphene shell which can be tuned by adjusting the SP operating conditions.

An excellent corrosion protection for copper nanoparticles by nitrogen-doped few-layer graphene via solution plasma process.     

Fabrication and characterization of electrospun PLLA/PANI/TSA fibers

Poly(l-lactic acid)/polyaniline/p-toluene sulfonic acid composites (PLLA/PANI/TSA) were synthesized via an emulsion polymerization-composition method with TSA as the dopant for PANI, and the structures and properties of the composites were characterized and analyzed. Conductive fiber tubes of PLLA/PANI/TSA were fabricated using electrospinning–knitting technology, and the effects of electrical stimulation on the growth and proliferation of osteoblast cells over the fiber tubes were investigated. The polymerization of PANI and the preparation of the PLLA/PANI/TSA composites were carried out via a one-step emulsion polymerization-composition or two-step method, where the reaction time of the two-step method was shorter and its yield higher than that of the one-step method. The addition of TSA improved the electrical conductivity of the PLLA/PANI composite and promoted chain propagation in the emulsion polymerization of the aniline oligomers and increased the degree of PANI polymerization. The PLLA/PANI/TSA fiber tubes obtained by electrospinning possessed regular morphologies and hydrophilic properties. Osteoblast cells grew and proliferated strongly with the PLLA/PANI/TSA fiber mats as a tissue scaffold and the electrical concentrating material under the condition of electrical stimulation of rectangular wave pulse signals with the appropriate stimulation current.

Poly(l-lactic acid)/polyaniline/TSA (PLLA/PANI/TSA) fiber mats play a positive role as a tissue scaffold for osteoblast cell proliferation.     

Nitrogen-doped graphene–TiOxNy nanocomposite electrode for highly efficient capacitive deionization

In this work, the first-ever reported nanocomposite electrode of nitrogen-doped graphene–titanium oxynitride (NG–TiO_xN_y) for capacitive deionization (CDI) was synthesized via hydrothermal reaction and a high-temperature nitridation process. The physiochemical characterizations revealed that the nitrogen was doped in the graphene structure mainly in the form of graphitic nitrogen and the TiO_xN_y was successfully formed via TiO₂ nitridation process. The layered NG nanosheets facilitated the diffusion of ions in saline water and formed electrical double layer on the surface of the electrode material, while the presence of TiO_xN_y enhanced the electrochemical performance by increasing surface area and generating surface vacancies via nitridation. The CDI cell employed NG–TiO_xN_y electrode delivered a breakthrough salt adsorption capacity of 26.1 mg g⁻¹ in 500 mg L⁻¹ saline water, and retained over 90% of its initial salt removal efficacy after 12 regeneration cycles. Such high CDI performance exhibits the promising application of NG–TiO_xN_y as a novel CDI electrode candidate.

A nanocomposite electrode of nitrogen-doped graphene and titanium oxynitride is applied as an effective and efficient electrode to deliver outstanding salt adsorption capacity in a flow-by capacitive deionization (CDI) cell.     

A stable TiO2–graphene nanocomposite anode with high rate capability for lithium-ion batteries

A rapid microwave hydrothermal process is adopted for the synthesis of titanium dioxide and reduced graphene oxide nanocomposites as high-performance anode materials for Li-ion batteries. With the assistance of hydrazine hydrate as a reducing agent, graphene oxide was reduced while TiO₂ nanoparticles were grown in situ on the nanosheets to obtain the nanocomposite material. The morphology of the nanocomposite obtained consisted of TiO₂ particles with a size of ∼100 nm, uniformly distributed on the reduced graphene oxide nanosheets. The as-prepared TiO₂–graphene nanocomposite was able to deliver a capacity of 250 mA h g⁻¹ ± 5% at 0.2C for more than 200 cycles with remarkably stable cycle life during the Li⁺ insertion/extraction process. In terms of high rate capability performance, the nanocomposite delivered discharge capacity of ca. 100 mA h g⁻¹ with >99% coulombic efficiency at C-rates of up to 20C. The enhanced electrochemical performance of the material in terms of high rate capability and cycling stability indicates that the as-developed TiO₂–rGO nanocomposites are promising electrode materials for future Li-ion batteries.

A rapid microwave hydrothermal process is adopted for the synthesis of titanium dioxide and reduced graphene oxide nanocomposites as high-performance anode materials for Li-ion batteries.     

Preparation of MoS2-based polydopamine-modified core–shell nanocomposites with elevated adsorption performances

New molybdenum disulfide (MoS₂)-based core–shell nanocomposite materials were successfully prepared through the self-assembly of mussel-inspired chemistry. Characterization by Fourier transform infrared, thermogravimetric analysis, scanning electron microscope and transmission electron microscopy revealed that the surface of the flaked MoS₂ was homogeneously coated with a thin layer of polydopamine (PDA). Dye adsorption performances of the synthesized MoS₂–PDA nanocomposites were investigated at different pH values and reaction times. Compared with pure MoS₂ nanosheets, the obtained core–shell nanocomposites showed elevated adsorption performances and high stability, indicating their potential applications in wastewater treatment and composite materials.

New core–shell MoS₂–PDA nanocomposites are prepared via mussel-inspired chemistry and a simple interfacial self-assembly process, demonstrating potential applications in wastewater treatment and self-assembled core–shell composite materials.     

Polyaniline nanorods random assembly on sugarcane bagasse pith-based carbon sheets with promising capacitive performance

Polyaniline (PANI) nanorods were randomly deposited on oxidized 2D sugarcane pith-based porous carbon nanosheets by using dilute polymerization methods. The random stacked morphology of the PANI nanorods on the oxidized pith-based porous carbon nanosheets (SPCN) can be effectively controlled by simply changing the molar mass of aniline monomer. When the molar mass of the aniline monomer is increased to 0.02 M, the PANI nanorods can be randomly and uniformly stacked on the oxidized SPCN. Most of these stacked pores derived from random stack of the PANI nanorods on the oxidized SPCN are mesopore and macropore. These stacked pores not only facilitate the diffusion of ions in the stacked layer of the PANI nanorods, but also mitigate mechanical deformation of the PANI nanorods during the doping/dedoping process. Furthermore, the relationship between the properties of the oxidized SPCN/PANI-X (X represents the molar mass of aniline monomer) electrode materials and molar mass of aniline monomer is explored in detail. The oxidized SPCN/PANI-0.02 exhibits the best electrochemical performance in 1 M H₂SO₄. The largest specific electrode capacitance is up to 513 F g⁻¹ at a current density of 0.25 A g⁻¹. The oxidized SPCN/PANI-0.02 also exhibits excellent electrochemical cycling stability.

Polyaniline nanorods are randomly stacked on the oxidized sugarcane bagasse pith-based carbon sheets by using the dilute polymerization methods, which exhibits excellent electrochemical performance.     

ZnSe nanoparticles dispersed in reduced graphene oxides with enhanced electrochemical properties in lithium/sodium ion batteries

A ZnSe-reduced graphene oxide (ZnSe-rGO) nanocomposite with ZnSe dispersed in rGO is prepared via a one-step hydrothermal method and applied as the anode materials for both lithium and sodium ion batteries (LIBs/SIBs). The as-prepared composite exhibits greatly enhanced reversible capacity, excellent cycling stability and rate capability (530 mA h g⁻¹ after 100 cycles at 500 mA g⁻¹ in LIBs, 259.5 mA h g⁻¹ after 50 cycles at the current density of 100 mA g⁻¹ in SIBs) compared with bare ZnSe in both lithium and sodium storage. The rGO plays an influential role in enhancing the conductivity of the nanocomposites, buffering the volume change and preventing the aggregation of ZnSe particles during the cycling process, thus securing the high structure stability and reversibility of the electrode.

ZnSe-rGO nanocomposite with ZnSe dispersed in reduced graphene oxides is studied as an anode for lithium and sodium ion batteries (LIBs/SIBs).     

Reversible conversion between graphene nanosheets and graphene nanoscrolls at room temperature

In this paper, the reversible conversion between pristine graphene nanosheets and pristine graphene nanoscrolls at room temperature was reported. The graphene nanosheets were rolled up into the graphene nanoscrolls by silver nitrate in ethanol solution, and the fabricated graphene nanoscrolls were unfolded back to the graphene nanosheets in ethanol solution by adding ammonium hydroxide. The dynamic conversion state of the process was confirmed by the morphology of the intermediate samples captured using an optical microscope and scanning electron microscope. Also, AFM, TEM and Raman spectroscopy displayed that the graphene transformed from its nanoscrolls remained the structure and morphology of the started graphene. The reason for the formation of the nanoscrolls was assigned to the silver cyanide particles generated on the edge of the graphene. The freshly formed silver cyanide caused the unbalanced energy of the graphene surface by changing the pi electron distribution and triggered off the graphene to roll up. The unfolding of the graphene nanoscrolls back to the graphene nanosheets was attributed to the removal of the silver cyanide by the ammonia via forming the complex. This reversible conversion might be a novel and facile approach to make graphene nanoscrolls and to store the graphene. Also, it may bring new sight to the conversion research between two-dimension and one-dimension materials.

The reversible conversion between the pristine graphene nanosheets exfoliated from graphite and the pristine graphene nanoscrolls was achieved at room temperature.     

Bio-elastomer nanocomposites reinforced with surface-modified graphene oxide prepared via in situ coordination polymerization

This article proposes a method to produce bio-elastomer nanocomposites, based on polyfarnesene or polymyrcene, reinforced with surface-modified graphene oxide (GO). The surface modification is performed by grafting alkylamines (octyl-, dodecyl-, and hexadecylamine) onto the surface of GO. The successful grafting was confirmed via spectroscopic (FTIR and Raman) and X-ray diffraction techniques. The estimated grafted amines appear to be around 30 wt%, as calculated via thermogravimetric analysis, increasing the inter-planar spacing among the nanosheets as a function of alkyl length in the amine. The resulting modified GOs were then used to prepare bio-elastomer nanocomposites via in situ coordination polymerization (using a ternary neodymium-based catalytic system), acting as reinforcing additives of polymyrcene and polyfarnesene. We demonstrated that the presence of the modified GO does not affect significantly the catalytic activity, nor the microstructure-control of the catalyst, which led to high cis-1,4 content bio-elastomers (>95%). Moreover, we show via rheometry that the presence of the modified-GO expands the capacity of the elastomer to store deformation or applied stress, as well as exhibit an activation energy an order of magnitude higher.

This article proposes a method to produce bio-elastomer nanocomposites, based on polyfarnesene or polymyrcene, reinforced with surface-modified graphene oxide (GO).     

The selective laser sintering of a polyamide 11/BaTiO3/graphene ternary piezoelectric nanocomposite

Piezoelectric materials featuring the capability of converting mechanical energy to electricity are very important for harvesting discrete mechanical energy to meet the rapidly increasing demand for cleaner energy. However, the intrinsic poor flexibility and processability make it difficult for current piezoelectric materials to fulfill their potential. This study reports a novel polyamide 11 (PA11)/BaTiO₃ (BT)/graphene (Gr) ternary nanocomposite 3D printed part with significantly enhanced dielectric and piezoelectric properties due to its special discontinuous graphene network and microspores. The piezoelectric BT nanoparticles with excellent piezoelectric properties were uniformly dispersed into PA11 via a solid-state shear milling (S³M) technology. Moreover, via ultrasonic coating and selective laser sintering (SLS) technology, the discontinuous graphene network and microporous structures were both fabricated in the prepared 3D printed parts. The graphene interfaces acted as electrodes, and thus significantly increased the poling efficiency, while the porous structure further magnified the stress concentration. As a result, a piezoelectric coefficient (d₃₃) of 3.8 pC N⁻¹ and open-circuit voltage of 16.2 ± 0.4 V were obtained, exhibiting better comprehensive performances than those of most reported piezoelectric materials.

Polyamide 11/BaTiO₃/graphene nanocomposite SLS part with enhanced dielectric and piezoelectric properties due to its special discontinuous graphene network and microspores.     

Facile solvothermal preparation of Fe3O4–Ag nanocomposite with excellent catalytic performance

Functional nanocomposites demonstrate excellent comprehensive properties and outstanding characteristics for numerous applications. Magnetic nanocomposites are an important type of composite materials, due to their applications in optics, medicine and catalysis. In this report, a new Fe₃O₄-loaded silver (Fe₃O₄–Ag) nanocomposite has been successfully synthesized via a simple solvothermal method and in situ growth of silver nanowires. The silver nanowires were prepared via the reduction of silver vanadate with the addition of uniformly dispersed Fe₃O₄ nanoparticles. Structural and morphological characterizations of the obtained Fe₃O₄–Ag nanocomposite were carried out using many characterization methods. As a new composite catalyst, the synthesized magnetic Fe₃O₄–Ag nanocomposite displayed a high utilization rate of catalytically active sites in catalytic reaction medium and showed good separation and recovery using an external magnetic field. The facile preparation and good catalytic performance of this Fe₃O₄–Ag nanocomposite material demonstrate its potential applications in catalytic treatment and composite materials.

A new Fe₃O₄–Ag nanocomposite was prepared via solvothermal method, demonstrating potential application in catalytic degradation of wastewater treatment and composite materials.