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It remains a huge challenge to create advanced elastomers combining high strength and great toughness. Despite enhanced strength and stiffness, elastomeric nanocomposites suffer notably reduced extensibility and toughness. Here, inspired by the concept of sacrificial bonding associated with many natural materials, a novel interface strategy is proposed to fabricate elastomer/graphene nanocomposites by constructing a strong yet sacrificial interface. This interface is composed of pyridine-Zn2+-catechol coordination motifs, which is strong enough to ensure uniform graphene dispersion and efficient stress transfer from matrix to fillers. Moreover, they are sacrificial under external stress, which dissipates much energy and facilitates chain orientation. As a result, the strength, modulus, and toughness of the elastomeric composites are simultaneously strikingly enhanced relative to elastomeric bulk. This work suggests a promising methodology of designing advanced elastomers with exceptional mechanical properties by engineering sacrificial bonds into the interface. [ABSTRACT FROM AUTHOR]

A novel method for producing graphene/hydroxypropyl cellulose (HPC) composite with a fine dispersion of graphene is established. The thermoresponsive HPC, with low a critical solution temperature (LCST) behavior, becomes self-associated into nanospheres when its homogeneous solution is heated to a temperature higher than the LCST. The formed nanospheres of HPC can then 'clamp' graphene layers and get them finely dispersed in solution and in the polymer matrix. Incorporating graphene via this method can largely prevent graphene from agglomeration. Compared with the conventional casting method, the proposed LCST method can further enhance the electrical conductivity of HPC/graphene composites by 2-3 orders of magnitude. The percolation threshold value of RGO loading is as low as 0.11 vol%. [ABSTRACT FROM AUTHOR]

An environmentally friendly method for preparing reduced graphene oxide (rGO) was established based on the typical hydrolysable tannin, tannic acid (TA). TA is fully competent in reducing GO and stabilizing rGO simultaneously. [ABSTRACT FROM AUTHOR]

Abstract: Individually dispersed graphene colloid is prepared using cationic dye rhodamine B (RhB) as a non-covalent modifier. Characterizations by UV–vis, photoluminescence and Raman, the graphene-RhB interactions are shown to be cation-π and π-π. Subsequently, the obtained graphene is incorporated into polyvinyl alcohol (PVA) to fabricate PVA/graphene composites by simple solution casting. On addition of 1.0 wt% graphene, the tensile strength and tensile modulus are increased by 178% and 139%, respectively. Interestingly, the strain of the composites is greatly maintained, which is related to the uniqueness interfacial structure and morphology of the composites. This work provides a promising methodology to fabricate high performance graphene-based composites with superior strength and ductility by simultaneously combining the reinforcement of graphene sheets and the uniqueness interfacial structure. [Copyright &y& Elsevier]

Graphical abstract Highlights • A novel hydrothermal self-assembled strategy is proposed for constructing 3D segregated graphene network in polymer matrix. • The shape of the products can be controlled by changing the types of reactors. • The nanocomposites present unique mechanical properties and competitive electrical conductivity. • The post-impregnation process can significantly improve the electrical conductivity of the nanocomposites. Abstract Constructing three-dimensional segregated graphene (3DG) network in polymer matrix is very effective in fabricating highly conductive polymer composites. However, it remains challenging to control the distribution of graphene with a concise and efficient method though the past efforts have been made. In this contribution, we propose a novel hydrothermal self-assembled strategy in combination of the post-impregnation process to prepare highly conductive polymer/graphene composites. Specifically, styrene-butadiene rubber/graphene nanocomposites with a three-dimensional graphene network (3DG-SBR) were prepared by employing the hydrothermal self-assembling, followed by impregnating by silver nitrate. The resultant graphene/styrene-butadiene rubber/silver particle (3DG-SBR-Ag) nanocomposite with 1.66 vol% of graphene exhibits the conductivity of 512 S m−1, which is competitive to those prepared by template-guided assembly strategy. Impressively, the polymer composite possesses mechanical robustness due to the strong interfacial reaction between graphene and polymer matrix. This synthetic approach for graphene-based nanocomposites is generic, scalable, flexibility in complex geometry and cost-effective. The as-prepared products could potentially be applied as competitive candidates for practical application in electromagnetic wave absorption and electromagnetic interference shielding. [ABSTRACT FROM AUTHOR]

Abstract A combination of malleability, supramechanical properties and multi-stimuli response into catalyst-free and commercially available polymer-based networks is particularly attractive to extend the realm of thermally malleable polymers. Toward this goal, herein we demonstrated a paradigm by introducing dynamic imine bonds into styrene-butadiene rubber (SBR)/graphene composites. SBR was firstly grafted with aldehyde groups and then cross-linked with p -phenylene diamine and it-modified graphene through imine condensation between aldehyde and amino groups. The crosslinked networks were able to alter their topologies via imine exchange reactions in both the bulk network and SBR-graphene interphase in the absence of catalyst, enabling them to be recycled and reshaped under heating or IR irradiation. The incorporation of graphene led to spectacular improvements on the mechanical properties of vitrimer composites, and the mechanical properties could be tuned through solid-state drawing. The relationships between morphological structure and dynamic properties as well as mechanical properties of the vitrimer composites were addressed. [ABSTRACT FROM AUTHOR]

It remains a huge challenge to realize the homogeneous graphene dispersion in elastomer matrix by a simple and general compounding method. Herein, we develop a straightforward slurry compounding method for preparation of rubber/graphene composites with well-dispersed graphene. Specifically, TPG (tea polyphenol reduced graphene)/ethanol slurry was first collected by solvent exchange after the reduction of graphene oxide by tea polyphenol and then directly melt compounded with chlorosulfonated polyethylene (CSM) in a two-roll mill to produce the composites. As revealed by the XRD and morphological studies, TPG homogeneously dispersed in CSM matrix, which together with the strong interfacial interaction between TPG and CSM contribute to the remarkable improvement in mechanical properties of the resulted composites. We envision that the present work offers a straightforward yet effective methodology for preparing high-performance elastomer/graphene composites via conventional melt compounding. [ABSTRACT FROM AUTHOR]

The exploitation of generic strategy for preparation of conductive elastomer composites with interconnected filler network is of significant scientific and technical interests. Herein, we report a novel, green and effective strategy to prepare conductive natural rubber (NR) composites with interconnected graphene network structure. It is found that the Pickering emulsion template is effective in constructing 3D interconnected graphene oxide (GO) networks while the thermal treatment during hot pressing step is able to convert GO to conductive thermal reduced graphene (TRG). This strategy does not rely on the toxic and corrosive reducing agents and the adopted solvents in Pickering emulsions can be recycled and reused, which makes the process environmentally friendly. As a result, interconnected graphene network is well constructed within NR matrix, which significantly enhances the electrical conductivity, mechanical properties and lowers the percolation threshold of the resulted composites. Specifically, with the incorporation of 1.90 vol% TRG, the electrical conductivity of NR composites with interconnected graphene network structure is more than 7 orders of magnitude higher than that of NR composites with uniform graphene dispersion. More intriguingly, this GO stabilized Pickering emulsion template strategy can also be used to realized the selective distribution of carbon nanotubes and assemble them into interconnected network structure, further facilitating the conductivity improvement of the resulted composites. Overall, we envision that the present work offers new insights into the design of conductive elastomer composites. [ABSTRACT FROM AUTHOR]

The energy loss of tires during service is closely related to the hysteresis of tire tread, which is governed by the dispersion and interface of the elastomer nanocomposites. However, traditional undeformable spherical fillers have approached a bottleneck in regulating the viscoelasticity and lowering the hysteresis loss. Herein, the designed covalent interface in the graphene/elastomer nanocomposite maximizes the reinforcement of the nanomaterial as well as minimizes the dynamic energy loss. The reinforced interfacial interaction, an ultralow percolation threshold of tensile strength and high reinforcement synergistically benefit these nano-organized rubber nanocomposites. The energy losses under dynamic loading are largely suppressed in this material, due to the reduced nano-scale frictions. The developed graphene/elastomer nanocomposites are applied to typical dynamic rubber product - auto tires, and the tests indicate that these tires possess energy efficiency close to the highest “A-grade”, which gave great economic and environmental improvements. The critical role of interface structure in the performance of the elastomer nanocomposites was revealed and new design strategy for low dynamic energy losses in rubber products was suggested. [ABSTRACT FROM AUTHOR]

In a rubber/filler composite, thesurface chemistry of the filler is a critical factor in determiningthe properties of the composite because it affects the dispersionof the filler and the interfacial adhesion between the filler andrubber. In this study, we primarily focus on how graphene surfacechemistry affects the dispersion of graphene and interfacial adhesionin butadiene–styrene rubber (SBR)/graphene composites and onthe resultant properties of the composites. Composites that containgraphene with tailored surface chemistry are prepared via the chemicalreduction of graphene oxide (GO) in situ. Subsequently,the dispersion of the graphene and interfacial adhesion are fullyinvestigated in relation to the graphene surface chemistry. As revealedby dielectric relaxation spectroscopy, the bulk segmental relaxationis independent of the graphene surface chemistry, whereas the interfacialrelaxation mode is retarded in the composite with stronger graphene–rubberaffinity. The contribution of the graphene surface chemistry to thedispersion of the graphene and interfacial adhesion is quantifiedby calculating the surface energies. The results indicate that, whenthe COxfraction in the graphene is greaterthan 0.2, it exerts an increasingly strong effect on the dispersionof the graphene; in contrast, when the COxfraction is less than 0.2, it exerts a significant and positiveeffect on the interfacial interaction. In particular, on the basisof the surface energy analysis, quantitative predictors for the dispersionof graphene and interfacial adhesion are presented; these predictorscan be used for the virtual design of graphene surface chemistry tooptimize the properties of composites. [ABSTRACT FROM AUTHOR]

Many reported polymer/graphene composites, even somewith excellent graphene dispersion, do not possess impressive conductivity,which may be due to the failure in forming interconnected conductivepaths. In this work, a kind of bio-based polyester (BE) is synthesizedby polycondensation between plant-derived diols and diacids. It isthen grafted onto graphene oxide (GO) via the easterification betweenhydroxyls of BE and carboxyls of GO. Subsequently, the grafted GOis subjected to reduce by vitamin C. Because of the presence of terminalhydroxyl group in both ends of the BE chains and multiple carboxylgroups on GO, the grafts form specific spatial interconnection structurein BE matrix. The resulting BE/graphene composites possess impressivelow threshold percolation of electrical conductivity, in combinationof high thermal conductivity. [ABSTRACT FROM AUTHOR]