Publications

Programming energy-dissipating units into polymers is an effective method to improve the toughness; however, the state-of-art approaches usually involve complicated chemistry manipulation and multistep process. In this contribution, we report a brand-new way to toughen styrene–butadiene rubber (SBR) by incorporating a sulfur-based ionomer to construct hierarchical coordination complexes. Specifically, the ionomer P(TA-S)/Fe containing polysulfide backbones and iron–carboxylate complexes was synthesized through the copolymerization of thioctic acid and sulfur, followed by introducing ferric chloride. Due to the reaction between polysulfide fragments in P(TA-S)/Fe and SBR, the incorporation of P(TA-S)/Fe enabled the chemical cross-linking of SBR and grafting of iron–carboxylate complexes onto SBR chains. The grafted iron–carboxylate complexes aggregated and formed a phase separate structure within SBR, which provided a multilevel energy-dissipating mechanism and consequently led to an integration of enhanced ultimate strength, modulus, and fracture toughness of SBR.

Front Cover: Inspired by the concept of the sacrificial bond, a strong yet sacrificial interface composed of metal-ligand coordination bonds is engineered in an elastomer/graphene composite. The strong interface ensures a high efficient stress transfer, meanwhile it is sacrificial during stretching, which dissipates enormous energy and facilitates rubber chain orientation. As a result, the composite exhibits a remarkable improvement in both strength and toughness. Further details can be found in the article by J. Huang, Z. Tang, Z. Yang, and B. Guo* on page 1040.

Two kinds of thiol ionic liquids (ILs), 1-methylimidazolium mercaptopropionate (MimMP) and bis (1-methylimidazolium) mercaptosuccinate (BMimMS), were investigated as novel interfacial modifiers for styrene butadiene rubber/halloysite nanotubes (SBR/HNTs) composites. According to model compounds, it was found that their affinities toward HNTs were originated from hydrogen bonding and that they could be grafted onto SBR chains via thiol-ene reactions. The ILs addition could promote vulcanization and effectively facilitate HNTs dispersion in rubber matrix. The interfacial interaction, quantitatively evaluated by a proposed equation based on rubber elasticity and reinforcement theory, was consistently increased. Mechanical properties of SBR/HNTs vulcanizates were largely improved and better than those of the 3-mercaptopropyl trimethoxysilane modified system. The BMimMS’s efficiency on modifying SBR/HNTs vulcanizates was higher than the other for its Gemini structure. Significantly mechanical improvements and lowered mechanical loss in the range of 50–80 °C were correlated to the improved HNTs dispersion and strengthened interfacial interactions.

Polydopamine (PDA) is a natural melanin derived from marine mussels that has good biocompatibility, biodegradability, and photothermal conversion ability. As a new coating material, it offers a novel way to modify the surface of various substances. The drug loading capacity and encapsulation efficiency of PDA are greatly improved via the use of mesoporous materials. The abundant pore canals on mesoporous polydopamine (MPDA) exhibit a uniquely large surface area, which provides a structural basis for drug delivery. In this review, we systematically summarized the characteristics and manufacturing process of MPDA, introduced its application in the diagnosis and treatment of cancer, and discussed the existing problems in its development and clinical application. This comprehensive review will facilitate further research on MPDA in the fields of medicine including cancer therapy, materials science, and biology.

In order to analyze the influence of the lateral size of graphene oxide (GO) on the properties of natural rubber/ graphene oxide (NR/GO) nanocomposites, three different sized graphene oxide sheets, namely G1, G2 and G3 were used to fabricate a series of NR/GO nanocomposites by latex mixing.The results indicate that adding GO can remarkably increase the modulus of NR.The enhancement of modulus is strongly dependent on the size of GO sheets incorporated.G1 with smallest sheet size gives the maximum reinforcement effect compared with G2 and G3.Dynamic mechanical measurement and swelling ratios (Q f /Q g ) indicate that G1 has stronger interfacial interaction with NR.XRD shows G1 is more effective in accelerating the strain-induced crystallization (SIC) of NR.The strong interfacial interaction facilitates the stress transfer and strain-induced crystallization, both of which lead to the improved modulus.

Elastomers with unique high elasticity are recognized as strategic materials. The development of elastomers with the combination of high-performance and functionality is of great importance. In recent years, inspired by the structural characteristics of natural materials, the concept of sacrificial bonding has been successfully applied in the design of elastomeric materials, aiming at significantly improving mechanical and functional properties. In this short review, followed by brief description of the principle of sacrificial bonding, we summarize the main progress of the design of the elastomers with sacrificial bonds, and the main performance characteristics. The sacrificial units, including the covalent and non-covalent sacrificial bonds, may be engineered in rubber chains or the interfaces of rubber nanocomposites. In addition, the mechanisms of sacrificial bonding in conferring the functionalities have been described. Several important functionalities, including shape memory effects, damping and self-healing capability combined with robustness, are introduced. Based on the state of the art of the elastomers with sacrificial bonds, the prospective and challenges of are accordingly presented and discussed.

No abstract is provided for this article.

It is a challenge to simultaneously achieve high stretchability, high modulus, and recoverability of polymers. Inspired by the multiphase structure of mussel byssus cuticles, we circumvent this dilemma by introducing a deformable microphase-separated granule with rich coordination into a ductile rubber network. The granule can serve as an additional cross-link to improve the modulus, while the sacrificial, reversible coordination can dissociate and reconstruct continuously during stretching to dissipate energy. The elastomer with such a bioinspired multiphase structure exhibits over a 10-fold increase in toughness compared to the original sample. We envision that this work offers a novel yet facile biomimetic route toward high-performance elastomers.

So far, most of the preparation methods for polymer/boron nitride nanosheets (BNNSs) composites are not suitable for mass production. Here, cost-effective and environmentally friendly water/ethanol were selected as the solvents to prepare BNNSs slurry on large scale by liquid exfoliation/solvent exchange. The slurry was then compounded with styrene-butadiene rubber (SBR) to form the rubber/BNNSs composites via conventional two-roll milling. The sulfide-containing silane was introduced to modify the interface between BNNSs and the rubber. The silane modified BNNSs (Si-BNNSs) has been characterized by FTIR, XPS and TGA. It is found that, with in situ modification of the silane, the rubber/BNNSs composites exhibited significantly improved thermal conductivity. With 10.5 vol% Si-BNNSs incorporated, the thermal conductivity of the composites is increased by 253%, comparing to the neat SBR. Meanwhile, the mechanical properties of the composites are simultaneously largely enhanced. The scalable yet environmentally-friendly slurry approach paves the way for industrial-scale utilization of BNNSs in thermally conductive polymer composites.

Biobased elastomers (bioelastomers) with high strength and good biocompatibility have emerged as promising biomaterials for soft tissue engineering. In the present work, we synthesized a series of biobased copolyesters, converting semicrystalline copolyesters into elastomers by introducing isosorbide, a bicyclic carbohydrate-based diol. The molecular weights, polymer structures and thermal transitions of the synthesized bioelastomers were characterized by GPC, NMR, FTIR, TGA, DSC and WAXD. The composition, melting point, and crystallinity of the bioelastomers could be tuned by changing the content of isosorbide. Furthermore, high strength composites could be prepared by compositing the synthesized bioelastomers with nanosilica. To substantiate the potential biocompatibility of the reinforced bioelastomers, the cell adhesion and proliferation were evaluated, and the results indicated that the reinforced bioelastomers were essentially noncytotoxic. The combination of sustainability, high strength and noncytotoxicity makes these bioelastomers potential candidates for high-strength biomedical materials.

Ruthenium (Ru) is considered as a promising element for constructing alkaline hydrogen evolution (HER) catalysts due to its rapid water dissociation kinetics and low-cost advantages than Pt. Alloying can optimize the electrochemical performance of metals and reduce the usage of the noble metal. Herin, RuCo alloy nanoparticles were grown in-situ on N-doped carbon nanofibers (RuCo/NCNF) by electrospinning and graphitization. Under thermodynamic driving force, the Ru and Co elements formed RuCo alloys. It is worth noting that the Ru not only improved the catalytic performance, but also reduced the nanoparticle size and exposing more active sites. Moreover, N-doped carbon nanofiber was not only used to load RuCo alloy nanoparticle, but also as a good substrate for the HER reaction. Therefore, the RuCo/NCNF had fabulous catalytic activity in alkaline media. Furthermore, the in-situ growth also endowed the RuCo/NCNF with excellent stability, HER performance was not significantly reduced even after 40 h stability test. And when the Ru:Co = 1:8, RuCo/NCNF had the excellent HER catalytic performance. Only 41 mV was required to drive a current density of 10 mA cm−2, with Tafel Slope as low as 64.8 mV dec−1.

Boehmite (BM) nanoplatelets were adopted to compound with fully biobased poly(propylene sebacate) (PPSe) to form the shape memory composites. The PPSe/BM composites kept excellent shape memory properties as previously reported PPSe. Compared to neat PPSe, the composites possess much higher mechanical properties above the melting point and faster biodegradation rate, which was demonstrated via tensile test at elevated temperature and in vitro degradation experiments in phosphate buffer saline (PBS), respectively. The obviously improved mechanical properties at elevated temperature are attributed to the uniform dispersion of the reinforcing boehmite nanoplatelets, which was facilitated by the interfacial interaction between BM and PPSe as revealed by FTIR, XPS, and XRD results. The faster degradation is correlated to accelerated hydrolysis by basic boehmite with surface aluminols. The potential biocompatibility, as substantiated by the outstanding cell viability and cell attachment, together with the realization of transformation temperature close to body temperature makes the PPSe/BM composites suitable for the biomedical applications, such as stents, in human body.

Vulcanization accelerant N-cyclohexyl-2-benzothiazole sulfenamide (CZ) was used as a surface modifier and chemically grafted on the surface of halloysite nanotubes (HNTs) to obtain CZ-functionalized HNTs (HNTs-s-CZ). It was found that HNTs-s-CZ could be homogeneously dispersed into styrene-butadiene rubber (SBR). The grafted CZ molecules, exactly located at the filler-rubber interface, reduced the activation energy of vulcanization of SBR/HNTs-s-CZ compounds. Besides, the density of chain segments introduced by the interfacial phase of SBR/HNTs-s-CZ nanocomposites was higher than the other nanocomposites with silane-modified HNTs (m-HNTs) or pristine HNTs, manifesting an indication of enhanced filler-rubber interfacial interaction in SBR/HNTs-s-CZ nanocomposites. Consequently, SBR/HNTs-s-CZ nanocomposites showed excellent mechanical properties. The tensile strength could be enhanced by as much as 38.6% and 102.5% compared to those of SBR/m-HNTs and SBR/HNTs nanocomposites, respectively, though containing equivalent accelerant component. The value of this work lies in the fact that apparent properties improvement of elastomer composites has been achieved by the incorporation of vulcanization accelerant-functionalized HNTs, which may be fruitful for the rational design of filler surface treatment and offer new scientific and technological opportunities for the preparation of high performance elastomer composites.

A novel strategy based on a multi-scale topological network design to prepare high-performance vegetable oil-based elastomers (VOEs) is proposed. The resulting VOEs with dual-network structures exhibit significant comprehensive advantages, including high vegetable oil content, simple and green synthesis process, transcendent low-temperature resistance, excellent mechanical properties, and outstanding reprocessability and self-healing capability.

Decorating the backbone of dielectric elastomers (DEs) with polar functionalities is an important practice that increases the total charge quantity of the chain segments, allowing DEs to have high dielectric permittivity (ε′). However, most established methods have struggled with optimizing the electromechanical performance of DEs, as the interactions among their polar functionalities have inevitably deteriorated the network flexibility of DEs. Herein, we present an innovative design concept for homogeneous DEs with superior dielectric properties by incorporating angle-containing monomers as building blocks that enable a flexible "zigzag" chain configuration in the DEs. This configuration, in turn, facilitates the charge separation within the chain segments. Therefore, a substantial increase of ε′ (∼90%) can be achieved while reducing the corresponding Young's modulus, enabling superior and dynamically stable actuation performance in DEs. These findings have the potential to break the longstanding trade-off between dielectric and mechanical performances of conventional DEs upon chemical decorations.