The strategy of using hybrid fillers with different geometric shapes and aspect ratios has been established to be an efficient way to achieve high-performance polymer composites. While, in spite of the recently renowned advances in this field, the mechanism of synergistic behavior in the system is still unclear and equivocal. In this study, we systematically investigated the mechanism for the synergistic reinforcement in an elastomer reinforced by nanocarbon hybrids consisting of 2D reduced graphene oxide (rGO) and 1D carbon nanotubes (CNTs). The improved dispersion state of hybrid filler was attested by Raman, UV-Vis spectra and morphological observations. In addition to the phenomenological evidences, we substantiated a stronger confinement effect of hybrid network on chain dynamics, for the first time, with molecular concepts by dielectric relaxation analysis. The formation of a glassy interphase with orders of magnitude slower chain dynamics than that for bulk chains has been explicitly demonstrated in the hybrid system. Besides improved dispersion upon hybridization, it is believed the formation of a glassy interphase is another crucial factor in governing the synergistic reinforcement capability of hybrid composites. We envision this new finding provides significant insight into the mechanism of synergistic behavior in hybrid-filled polymer composites with molecular concepts.

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.

Functional elastomer nanocomposites have found numerous applications in diverse hi-tech areas. Transport phenomena, such as electrical conductivity, thermal conductivity and gas/liquid barrier properties, have been the major focus of functional elastomer nanocomposite research. Despite essential progress in these areas, a summary and discussion of state-of-the-art strategies for regulating the transport performances of nanocomposites based on the transportation mechanisms of electrons, phonons and mass are lacking. In the present review, a brief introduction of transport mechanisms in elastomer nanocomposites precedes a systematic summary of the important progress in elastomer nanocomposites with electrical/thermal conductivities and lowered mass permeabilities, with emphasis on the latest structural control strategies for tuning transport properties. Key applications of functional elastomer nanocomposites related to transport phenomena are also introduced. Overall, this review summarizes the state of the art in the design and performance enhancement of elastomer nanocomposites based on the relationships between their structures and transport properties, governed by the components/composition, interface/dispersion and fabrication.

Reinforcing rubbers and expanding their application galleries are two important issues in material science and engineering. In this work, we demonstrate a bioinspired design of high-performance and macroscopically responsive diene-rubber by engineering sacrificial metal–ligand motifs into a chemically cross-linked architecture network. The metal–ligand bonds are formed through the coordination reaction between the pyridine groups in butadiene–styrene–vinylpyridine rubber (VPR) and metal ions. Under external load, the metal–ligand bonds serve as sacrificial bonds that preferentially rupture prior to the covalent network, which dissipates energy and facilitates rubber chain orientation. Based on the function mechanisms, the modulus, tensile strength, and toughness of the samples are simultaneously improved without sacrificing the extensibility, and these properties can be conveniently tuned by varying the structure parameters of the covalently cross-linked network and metal–ligand bonds. Moreover, the dissociation/re-formation of metal–ligand bonds upon heating/cooling can endow VPR with thermally triggered adaptive recovery for shape memory application.

The application of polymers as an essential class of material was greatly inhibited due to the aging failure of these versatile materials during normal use. Hence, it is generally recognized that stabilization against thermo-oxidative aging is indispensable to extend the service life of polymers for long-term applications. However, toxicity and pollution of the state-of-the-art antiaging technologies have long been puzzles in the polymer industry. Herein, sustainable carbon nanodots (CDs), synthesized by facile and cost-effective microwave-assisted pyrolysis, are used for first time as radical scavengers to resist the thermo-oxidative aging of elastomers. We have demonstrated that incorporation of the resultant CDs could be green and generic radical scavengers toward highly aging-resistant elastomers. Furthermore, by controlling the photoluminescent quantum yield of the CDs with various passivated agents, tunable radical scavenging activity was achieved. We established for the first time that the aging resistance originates from the prominent reactive radical scavenging activity of the CDs, which was rationally controlled by their photoluminescent quantum yield.

Sulphur-cured diene-based rubbers generally suffer from insufficient anti-ageing properties, and the curing process involves the use of toxic additives. Renewable conjugated acids are demonstrated to effectively cure epoxidized natural rubber into a high-performance elastomer, without the use of any toxic accelerators or antioxidants.

In a rubber/filler composite, the surface chemistry of the filler is a critical factor in determining the properties of the composite because it affects the dispersion of the filler and the interfacial adhesion between the filler and rubber. In this study, we primarily focus on how graphene surface chemistry affects the dispersion of graphene and interfacial adhesion in butadiene–styrene rubber (SBR)/graphene composites and on the resultant properties of the composites. Composites that contain graphene with tailored surface chemistry are prepared via the chemical reduction of graphene oxide (GO) in situ. Subsequently, the dispersion of the graphene and interfacial adhesion are fully investigated in relation to the graphene surface chemistry. As revealed by dielectric relaxation spectroscopy, the bulk segmental relaxation is independent of the graphene surface chemistry, whereas the interfacial relaxation mode is retarded in the composite with stronger graphene–rubber affinity. The contribution of the graphene surface chemistry to the dispersion of the graphene and interfacial adhesion is quantified by calculating the surface energies. The results indicate that, when the COx fraction in the graphene is greater than 0.2, it exerts an increasingly strong effect on the dispersion of the graphene; in contrast, when the COx fraction is less than 0.2, it exerts a significant and positive effect on the interfacial interaction. In particular, on the basis of the surface energy analysis, quantitative predictors for the dispersion of graphene and interfacial adhesion are presented; these predictors can be used for the virtual design of graphene surface chemistry to optimize the properties of composites.

State-of-the-art processes cannot achieve rubber/multi-walled carbon nanotube (MWCNT) composites with satisfactory performance by using pristine MWCNTs and conventional processing equipment. In this work, high performance rubber/MWCNT composites featuring a combination of good mechanical properties, electrical and thermal conductivities and damping capacity over a wide temperature range are fabricated based on a well-developed master batch process. It is demonstrated that the MWCNTs are dispersed homogeneously due to the disentanglement induced by well-wetting and shearing, and the elastic-resilience-induced dispersion of the MWCNTs by rubber chains via the novel processing method. To further enhance the efficacy of elastic-resilience-induced dispersion for MWCNTs, a slightly pre-crosslinked network is constructed in the master batch. Consequently, we obtain rubber/MWCNT composites with unprecedented performance by amplifying the reinforcing effect of relatively low MWCNT loading. This work provides a novel insight into the fabrication of high performance functional elastomeric composites with pristine CNTs by taking advantage of the unique elastic resilience of rubber chains as the driving force for the disentanglement of CNTs.

To fully exhibit the potentials of the fascinating characteristics of graphene oxide (GO) in polymer, the achievement of strong interface interactions and fine dispersion of GO in the hybrids is essential. In the present work, the elastomeric hybrids consisting of GO sheets are fabricated by utilizing butadiene–styrene–vinyl pyridine rubber (VPR) as the host through co-coagulation process and in situ formation of an ionic bonding interface. The VPR/GO composites with a normal hydrogen bonding interface are also prepared. The mechanical properties and gas permeability of these hybrids with an ionic bonding interface are obviously superior to those of the composites with a hydrogen bonding interface. With the ionic interfacial bonding, inclusion of 3.6 vol% of GO in VPR generates a 21-fold increase in glassy modulus, 7.5-fold increase in rubbery modulus, and 3.5-fold increase in tensile strength. The very fine dispersion of GO and the strong ionic interface in the hybrids are responsible for such unprecedented reinforcing efficiency of GO towards VPR. This work contributes new insights on the preparation of GO-based polymer hybrids with high performance.

From the point of better biocompatibility and sustainability, biobased shape memory polymers (SMPs) are highly desired. We used 1,3-propanediol, sebacic acid, and itaconic acid, which have been industrially produced via fermentation or extraction with large quantities as the main raw materials for the synthesis of biobased poly(propylene sebacate). Diethylene glycol was used to tailor the flexibility of the polyester. The resulted polyesters were found to be promising SMPs with excellent shape recovery and fixity (near 100% and independent of thermomechanical cycles). The switching temperature and recovery speed of the SMPs are tunable by controlling the composition of the polyesters and their curing extent. The continuously changed switching temperature ranging from 12 to 54 °C was realized. Such temperature range is typical for biomedical applications in the human body. The molecular and crystalline structures were explored to correlate to the shape memory behavior. The combination of potential biocompatibility and biodegradability of the biobased SMPs makes them suitable for fabricating biomedical devices.