In situ thermal reduction of graphene oxide in a styrene–ethylene/butylene–styrene triblock copolymer via melt blending

We report an in situ thermal reduction of graphene oxide (GO) in a styrene–ethylene/butylene–styrene (SEBS) triblock copolymer matrix during a melt‐blending process. A relatively high degree of reduction was achieved by melt‐blending premixed GO/SEBS nanocomposites in a Haake mixer for 25 min at 225 °C. Infrared spectral results revealed the successful thermal reduction of, and the strong adsorption of SEBS on, the graphene sheets. The glass transition temperature of polystyrene (PS) segments in SEBS was enhanced by the incorporation of thermally reduced graphene oxide (TRGO). The resultant TRGO/SEBS nanocomposites were used as a masterbatch to improve the mechanical properties of PS. Both the elongation at break and the flexural strength of PS/SEBS blends were enhanced with the addition of the TRGO. Our demonstration of the in situ thermal reduction of GO via melt blending is a simple, efficient strategy for preparing nanocomposites with well‐dispersed TRGO in the polymer matrix, which could be an important route for large‐scale fabrication of high‐performance graphene/polymer nanocomposites. © 2013 Society of Chemical Industry     

A Review on Polymeric Nanocomposites of Nanodiamond,Carbon Nanotube,and Nanobifiller: Structure,Preparation and Properties

In this review, an overview of various types of nanofillers is presented with special emphasis on structure, synthesis and properties of carbon nanotube, nanodiamond, and nanobifiller of carbon nanotube/nanodiamond, carbon nanotube/graphene oxide and carbon nanotube/graphene. In addition, polymer/carbon nanotube, polymer/nanodiamond, and polymer/nanobifiller composites have been discussed. The efficacy of different fabrication techniques for nanocomposites (solution casting, in-situ, and melt blending method) and their properties were also discussed in detail. Finally, we have summarized the challenges and future prospects of polymer nanocomposites reinforced with carbon nanofillers hoping to facilitate progress in the emerging area of nanobifiller technology.     

The preparation and properties of polystyrene/functionalized graphene nanocomposite foams using supercritical carbon dioxide

In this work, polystyrene (PS)/functionalized graphene nanocomposite foams were prepared using supercritical carbon dioxide. Thermally reduced graphene oxide (TRG) and graphene oxide (GO) were incorporated into the PS. Subsequently, the nanocomposites were foamed with supercritical CO₂. The morphology and properties of the nanocomposites and the nucleation efficiency of functionalized graphene in foaming PS are discussed. Compared with GO, TRG exhibited a higher nucleation efficiency and more effective cell expansion inhibition thanks to its larger surface area and better exfoliated structure. It is suggested that the factors that have a significant influence on the nucleation efficiency of TRG and GO originate from the differences in surface properties and chemical structure. Furthermore, PS/TRG nanocomposites and their nanocomposite foams also possess good electrical properties which enable them to be used as lightweight functional materials.© 2012 Society of Chemical Industry     

水辅混炼挤出聚苯乙烯/氧化石墨烯纳米复合材料的微观结构及流变与热性能

采用自主设计的水辅混炼挤出设备,制备3种氧化石墨烯（GO）含量（0.1 %、0.3 %、0.5 %,质量分数,下同）的聚苯乙烯（PS）/GO纳米复合材料,观察样品的微观结构,测试其流变性能和热性能。结果表明,GO被较好剥离且呈网状较均匀地分散在PS基体中,这主要归因于螺杆混炼流场不断细化PS熔体中的GO悬浮液以及水对熔体的塑化和溶胀效应促进PS分子链插层进入GO片层之间的共同作用;低频区PS/GO样品的储能模量、复数黏度和松弛时间均比纯PS样品的高,这是因为较均匀分散的网状GO片与PS之间形成较强的分子间作用力,降低了PS分子链的活动性;PS/GO样品的热稳定性比纯PS样品的高,这归因于GO片在PS基体中呈网状分布和GO表面存在π键。     

Performance enhancement of polylactide by nanoblending with POSS and graphene oxide

We report the effect of filler modification on the properties of polylactide (PLA)‐based nanocomposites, where graphene oxide (GO) nanosheets and polyhedral oligomeric silsesquioxane (POSS) nanocages are employed as nanofillers. The organically treated nanofillers are termed as GO‐functionalized and POSS‐functionalized. The synthesis of the nanocomposites was carried out via in situ ring‐opening polymerization of lactic acid (LA). The following four naocomposite systems were prepared, characterized, and compared to achieve a better understanding of structure‐property relationship (1) PLA/GO‐functionalized, (2) PLA/POSS‐functionalized, (3) PLA/physical mixture of GO‐functionalized and POSS‐functionalized, and (4) PLA/GO‐graft‐POSS (with eight hydroxyl groups). As revealed by the thermal and mechanical (nanoindendation) characterization, that the nanocomposites having a combination of GO and POSS as nanofiller, either as physical mixture of GO‐functionalized and POSS‐functionalized or as GO‐graft‐POSS, is far more superior as compared with the nanocomposites having individually dispersed nanofillers in the PLA matrix. Observed enhancement is attributing to the synergistic effect of the nanofillers as well as better dispersion of the modified‐fillers in the matrix. POLYM. COMPOS., 35:118–126, 2014. © 2013 Society of Plastics Engineers     

A comparison of thermoplastic polyurethane incorporated with graphene oxide and thermally reduced graphene oxide: Reduction is not always necessary

Despite wide applications of reduced graphene-oxide (GO)-reinforced polymer-based composites, the necessity of the reduction procedure toward GO is still controversial. In this article, thermoplastic polyurethane (TPU) composites incorporated with GO and thermally reduced graphene oxide (TGO) were fabricated. GO and TGO exhibited different effects on crystallization behaviors, and mechanical and thermal properties of the TPU matrix. With 2.0 wt % filler loading, TPU composite reinforced by GO (TPU-GO-2 wt %) exhibited better thermal stability than that reinforced by TGO (TPU-TGO-2 wt %). The interfacial interaction between the nanofillers and the TPU matrix as well as their influence on the mobility of TPU chains were investigated, which proved that GO is superior to TGO in improving interface adhesion and maintaining crystallization of the TPU matrix. Compared with TPU-TGO-2 wt %, improved mechanical properties of TPU-GO-2 wt % were also evidenced owing to more oxygen-containing groups. This work demonstrates that the reduction of GO is not always necessary in fabricating polymer composites. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47745.     

Enhancement of thermal,morphological, and mechanical properties of compatibilized based on PA6-enriched graphene oxide/EPDM-g-MA/CR: Graphene oxide and EPDM-g-MA compatibilizer role

In this study, a series of elastomeric nanocomposites based on specific amounts of polyamide6 (PA6)/chloroprene rubber (CR) blends which are compatibilized with ethylene propylene diene monomer-grafted-maleic anhydride (EPDM-g-MA) and different amounts of graphene oxide (GO) were prepared with melt mixing method. The effect of compatibilizer and reinforcement concentration in the PA6/CR blend matrix was investigated using theoretical and experimental analysis. Dispersion of nanoplatelets within rubber blend matrix was proven with transmission electron microscopy and field emission-scanning electron microscopy. The modified microstructure of samples showed the significant effect of EPDM-g-MA and GO on the size reduction of CR droplets in the PA6 continuous phase. The results from differential scanning calorimetry and dynamic mechanical thermal analysis revealed the effect of EPDM-g-MA and GO as an effective nucleating agent in PA6-enriched GO/CR (PA6EGO/CR). The findings obtained from thermogravimetric analysis displayed that the GO in the presence of an EPDM-g-MA as a compatibilizer can cause a higher thermal stability in PA6EGO/CR. From mechanical properties, by adding a compatibilizer to the PA6/CR blend, the tensile strength changed from 39.0 to 45.1, the Young's modulus altered from 522.2 to 716.0 and the elongation at break changed from 246.8 to 222.2. While incorporation of 5 phr of GO to the compatibilized blend, the tensile strength increased by 25.2%, the Young's modulus increased by 36.6% and the elongation at break decreased by 20%. The Christensen–Lo model used for analyzing the stiffness of PA6EGO/EPDM-g-MA/CR with emphasis on the influence of the interphase region to predict the effect of various loadings of GO and EPDM-g-MA of Young's modulus. The rheology and creep tests showed a significant effect of EPDM-g-MA and GO content on the rheology behavior of nanocomposites.     

Ductile/brittle PA6/PS system: Effect of carbon nanoplatelets-modified interface on performance

Addition of rigid PS to ductile PA6 can lead to higher toughness provided plastic deformation of PS is achieved. The current study deals with upgrading of this system by graphene, graphene oxide (GO), and GO with grafted polystyrene (GO-g-PS). Low amount of these carbon nanoplatelets can enhance performance of the PA/PS 90/10 system with the best-balanced properties achieved with GO-g-PS by unique combination of reinforcement with the favorable effect of the GO-g-PS-modified interface on plastic deformation of the PS phase causing higher impact resistance. Simultaneous linking of PA chains and hydrogen bonding causes “anchoring” of PS inclusions in the PA6 phase. This results in support of hydrostatic pressure evolution during loading and thus extensive yielding of PS. Another positive effect is reduction of pullout of in situ formed fibrous inclusions, which is different from rigid short-fiber composites. The study highlights high potential of GO modified with polymer chains to upgrade polymer systems via tailoring the interface.     

Fabrication of polymer/microwave‐reduced graphite oxide nanocomposites by ball‐milling assisted wet compounding

Microwave‐induced reduction of graphite oxide (GO) is a promising method for rapid and scalable production of graphene. However, homogeneous incorporation of thus prepared graphene into polymer matrix is still a hard task. In this article, we present a ball‐milling assisted wet compounding method for the fabrications of microwave‐reduced GO (MRGO)/polymer composites. MRGO powders were added into a solution of polystyrene (PS) and then mechanically exfoliated in a stirring mill. Scanning electron microscopy and transmission electron microscopy investigations show that the graphene sheets have been homogeneously dispersed in the PS matrix. The composites show pronouncedly improved properties. The thermal degradation temperature of composites increased by 34°C with the addition of 5wt% MRGO in PS. Up to 76% improvement of storage modulus (at 30°C) is achieved by compounding with 10wt% MRGO.POLYM. COMPOS., 2013. © 2013 Society of Plastics Engineers     

Synergetic Effects of Graphene Oxide and Clay on the Microstructure and Properties of HIPS/Graphene Oxide/Clay Nanocomposites

In this paper, double-network structure nanocomposite with improved mechanical and thermal properties were prepared using high-impact polystyrene as a matrix phase, clay and graphene oxide as effective reinforcing fillers through a facile solution intercalation method. The structure and morphology of nanocomposites were characterized by transmission electron microscopy, scanning electron microscopy, X-ray diffraction analysis, and the synergetic effects of clay and graphene oxide on the final properties were investigated using tensile, dynamic mechanical thermal analysis (DMTA) and thermogravimetric analysis (TGA) analysis. Mechanical analysis showed that the combination of graphene oxide and clay exerted a favorable synergistic effect on the tensile modulus and the yield strength of the ternary composite that are greatly improved as compared with neat high-impact polystyrene, high-impact polystyrene/graphene oxide, and high-impact polystyrene/clay binary composites due to the double-network structure formation between the nanofillers as confirmed by the direct morphological observations using transmission electron microscopy and scanning electron microscopy analysis. The viscoelastic behavior showed that storage modulus of ternary composite significantly improvement over than that of the pure matrix, high-impact polystyrene/graphene oxide and high-impact polystyrene/clay while network structure made. TGA and DMTA measurements also demonstrated that thermal stability of high-impact polystyrene matrix modified by graphene oxide and clay slightly enhanced during the creation of dual network structure of graphene oxide and clay. Our data suggest a potential application for the combination of graphene oxide and clay in graphene-based composite materials.     

聚苯乙烯/氧化石墨烯复合建材的制备与保温性能研究

通过聚苯乙烯(PS)与氧化石墨烯(GO)共混,制备聚苯乙烯/氧化石墨烯(PS/GO)保温建筑材料,并对PS/GO阻燃性能以及保温性能进行研究。结果表明:GO含量为6%时,4号样品的综合性能最好。4号样品的LOI值为33.4%,阻燃等级达到V-1,热释放速率峰值(pHRR)为525.76 kW/m²,总产烟量(TSP)为629.37 m²。此外,4号样品具有较低的导热系数0.034 2 W/(m·K),并且吸水率以及水蒸气透过系数均满足标准值,说明其可以有效应用于建筑保温材料。     

Fabrication and characteristics of graphene oxide/nanocellulose fiber/poly(vinyl alcohol) film

Poly(vinyl alcohol) (PVA), PVA/nanocellulose fiber (CNF), and PVA/CNF/graphene oxide (GO) films were prepared simply by casting stable aqueous mixed solutions. FTIR investigation indicated that hydrogen bonding existed between the interface of GO and PVA‐CNF. Scanning electron microscopy and X‐ray diffraction analysis showed that GO was uniformly dispersed in PVA‐CNF matrix. Introducing CNF into PVA caused a significant improvement in tensile strength, and further incorporating GO into PVA/CNF matrix led to a further increase. The tensile strength of the neat PVA film, PVA/CNF composite, and PVA/CNF/GO film (0.6 wt % GO) was 43, 69, and 80 MPa, respectively. Moreover, when incorporating 8 wt % CNF into PVA matrix, O₂ permeability and water absorption decreased from 13.36 to 11.66 cm³/m²/day and from 164.2% to 98.8%, respectively. Further adding 0.6 wt % GO into PVA/CNF matrix resulted in a further decrease of permeability and water absorption to 3.19 cm³/m²/day and 91.2%, respectively. Furthermore, for all composite samples, the transmittance of visible light was higher than 67% at 800 nm. CNF and GO‐reinforced PVA with high mechanical and barrier properties are potential candidates for packaging industry. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45345.     

Synergistic effect of graphene oxide‐silver nanofillers on engineering performances of polyelectrolyte complex nanofiber membranes

The poor mechanical and antibacterial performance has become a big hurdle for extending the application of polyelectrolyte complex (PEC) nanofibers in various fields. In this study, chitosan/gelatin (CG) composite nanofiber system was used for portraying the synergistic enhancement of mechanical and antibacterial properties of PEC nanofiber membranes by inclusion of graphene oxide‐silver (GO‐Ag) nanofillers. In particular, the introduction of 1.5 wt % GO‐Ag has raised the elastic modulus and tensile strength of CG nanofiber membrane by 105% and 488%, respectively, which are partially attributed to the alleviated restacking of graphene sheets by the anchored AgNPs. Meanwhile, the diameters of inhibition zone against Escherichia coli and Staphylococcus aureus on LB‐agar plates induced by GO‐Ag/CG nanofiber membranes are increased by 80.5% and 50.1%, respectively, compared to that by CG membrane. The synergistic improvement of antimicrobial performance of GO‐Ag/CG may be related to the accumulation of microorganisms induced by GO. In summary, the incorporation of GO‐Ag composite nanofillers has emerged as an effective strategy for engineering PEC nanofiber membranes for potential applications in nanomedicine and tissue engineering. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46238.     

Improved properties of highly oriented graphene/polymer nanocomposites

A kind of molecular‐level dispersed and highly oriented graphene monolayer nanocomposite film was successfully obtained by in situ reduction of phenyl isocyanate functionalized graphite oxide (RPIGO) in N,N‐dimethylformamide in the presence of polystyrene (PS). Atomic force microscopy and transmission electron microscopy results show that the RPIGO monolayers were not only homogeneously intercalated into the PS matrix but also arranged parallel to the surface of the nanocomposite films. Because of the efficient interaction between the graphene monolayers and PS matrix, the mechanical properties of the graphene‐based nanocomposite films improved significantly. Compared with the pure PS film, a 28.4% increase in the Young's modulus and a 27.8% improvement in the tensile strength of the RPIGO–PS nanocomposites films were obtained with the addition of only 0.5 wt % graphite oxide. The glass‐transition temperature and onset degradation temperature of PS also increased from 96.6 and 427°C to 103.2 and 439°C, respectively. The improvement of the properties was mainly due to the large lateral thickness ratio and the high orientation of graphene monolayers. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Preparation and Properties of Ethylene-vinyl Acetate/linear Low-density Polyethylene/Graphene Oxide Nanocomposite Films

Ethylene-vinyl acetate-based nanocomposites with 18 and 28 wt% vinyl acetate were prepared via solution casting method. To improve the mechanical and barrier properties of ethylene-vinyl acetate, linear low-density polyethylene, and graphene oxide were introduced to matrix. The morphological studies indicated that the graphene oxide diffraction peak disappeared in all prepared nanocomposites, probably due to its exfoliation; also proper dispersion and good interaction between nanofillers and polymer matrix were achieved. By introducing low amount of graphene oxide into the matrix, the mechanical and thermal properties and oxygen permeability were improved especially for those with 28 wt% vinyl acetate monomer.     

Preparation of polyimide/siloxane‐functionalized graphene oxide composite films with high mechanical properties and thermal stability via in situ polymerization

An effective approach to prepare polyimide/siloxane‐functionalized graphene oxide composite films is reported. The siloxane‐functionalized graphene oxide was obtained by treating graphene oxide (GO) with 1,3‐bis(3‐aminopropyl)‐1,1,3,3‐tetra‐methyldisiloxane (DSX) to obtain DSX‐GO nanosheets, which provided a starting platform for in situ fabrication of the composites by grafting polyimide (PI) chains at the reactive sites of functional DSX‐GO nanosheets. DSX‐GO bonded with the PI matrix through amide linkage to form PI‐DSX‐GO films, in which DSX‐GO exhibited excellent dispersibility and compatibility. It is demonstrated that the obvious reinforcing effect of GO to PI in mechanical properties and thermal stability for PI‐DSX‐GO is obtained. The tensile strength of a composite film containing 1.0 wt% DSX‐GO was 2.8 times greater than that of neat PI films, and Young's modulus was 6.3 times than that of neat PI films. Furthermore, the decomposition temperature of the composite for 5% weight loss was approximately 30 °C higher than that of neat PI films. © 2015 Society of Chemical Industry     

Pervaporation of toluene and iso‐octane through poly(vinyl alcohol)/graphene oxide nanoplate mixed matrix membranes: Comparison of crosslinked and noncrosslinked membranes

Removal of aromatic compounds from fuel is an essential requirement in new environmental policies. In the present study, poly(vinyl alcohol)/graphene oxide (GO) mixed matrix membranes were prepared and applied to the separation of toluene from iso‐octane by pervaporation, considering the similarity and interaction between graphene and aromatics. The effects of crosslinking and GO content on separation efficiency have been investigated in detail. Owing to the high affinity of GO with toluene through s and π bonds, the selectivity of the membranes was increased by incorporating a low amount of GO. The results also indicated that noncrosslinked membranes have higher selectivity and permeation flux due to higher crystallinity and also have lower mechanical properties. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45853.     

Improving the mechanical properties of graphene oxide based materials by covalent attachment of polymer chains

We report on the modification of graphene oxide (GO) with poly(vinyl alcohol) (PVA) leading to the mechanical improvement of GO based materials. First, GO was covalently functionalised with PVA by esterification of carboxylic groups on GO with hydroxyl groups of PVA resulting in functionalised f-(PVA)GO. This was carried out for PVA of six different molecular weights. This functionalised graphene oxide could be formed into a paper-like material by vacuum filtration. Papers prepared from f-(PVA)GO showed significant increases in mechanical properties compared to those prepared with GO or with simple mixtures of GO and PVA. The best performance was achieved for PVA functional groups with molecular weights between 50 and 150 kg/mol. Improvements in Young’s moduli of 60% and tensile strength of 400% were observed relative to GO-only paper. The improved mechanical properties are attributed to enhanced inter-flake stress transfer due to the covalently bonded PVA. Second, functionalised f-(PVA)GO was used as filler in PVA-based composites. The application of a pre-selection method allowed the use of only the largest functionalised f-(PVA)GO flakes. This resulted in substantially reinforced PVA–f-(PVA)GO composites. Both modulus and strength increased by 40% relative to the pure polymer for f-(PVA)GO loadings below 0.3 vol.%.     

Effect of surface modification of graphene oxide on photochemical stability of poly(vinyl alcohol)/graphene oxide composites

Poly(vinyl alcohol) (PVA)/graphene oxide (GO) composites were prepared to improve the photochemical stability of PVA. The surface of GO was modified by oxyfluorination to introduce the polar functional groups on GO for the stronger interfacial interaction with PVA. The photochemical stability of PVA/oxyfluorinated-GO composites was evaluated by measuring the insoluble gel content after partial photodegradation of PVA under various UV irradiations. PVA/oxyfluorinated-GO composites showed the significant improvement in both the dispersion of GO in PVA matrix and the photochemical stability of PVA as the oxygen content increased in the oxyfluorination. The photochemical stability of composites had a close relation with the uniform distribution of GO in PVA matrix. The proper modification of GO by oxyfluorination showed the better photochemical stability for PVA/GO composites as compared to that of PVA/pristine GO composite.     

Coupling hybrid of graphene oxide and layered zirconium phosphonate to enhance phenolic resin–based friction materials

A two‐dimensional (2D) heterogeneous coupling nanoparticle composed of graphene oxide and zirconium phosphonate (GO‐ZrP) was synthesized layer by layer in a self‐assembly manner. A rigid layer of zirconium phosphonate can inhibit the curling of graphene oxide and then improve its dispersion. The GO‐ZrP was then applied to phenolic resin–based friction materials by blending and hot pressing to improve their friction properties. The results show that the phenolic resin–based friction materials modified by GO‐ZrP possess excellent tribological, mechanical, and thermal properties. Also, the specific wear rate of the material decreased nearly fivefold with the optimal loading, while the friction coefficient was basically stable. Synergistic effects between GO and ZrP nanosheets provide good prospects for the application of 2D nanofillers in friction materials. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46543.