Publications

The reinforcement of plastic polymers by using the synergetic effects of two different fillers has sparked great interest, however, few works have been devoted to elastomers. In the present work, a tannic acid functionalized graphene (TAG) aqueous dispersion was prepared and hybridized with tubular clay, halloysite nanotubes (HNTs), to prepare a hybrid colloid (HNTs–TAG). The driving force for the hybridization was shown to be the specific interactions (hydrogen bonding and bridged bidentate bonding) between the catechols on TAG and the alumina/siloxane surfaces of HNTs. The obtained hybrid colloid was then co-coagulated with styrene-butadiene rubber (SBR) emulsion to prepare elastomeric composites. The results showed that a 3D hybrid filler network consisting of HNTs and TAG was developed and served as a novel networked reinforcement in the SBR matrix. The formed hybrid filler network, together with the enhanced interfacial interaction, is considered to be responsible for the significant synergetic effects in the improvement of the modulus and strength of the composites.

In this study, nanosheets including graphene oxide (GO) and reduced graphene oxide (rGO), were incorporated into natural rubber (NR), to study the effects of substituting GO or rGO for carbon black (CB) on the structure and performance of NR/CB composites. The morphological observations revealed the dispersion of CB was improved by partially substituting nanosheets for CB. The improvements in static and dynamic mechanical properties were achieved at small substitution content of GO or rGO nanosheets. With substitution of rGO nanosheets, significant improvement in flex cracking resistance was achieved. NR/CB/rGO (NRG) composites has a much lower heat build‐up value compared with NR/CB/GO (NG) composites at a high load of nanosheets. However, both GO and rGO tended to aggregate at a high concentration, which led to the poor efficiency on enhancing the dynamic properties, or even deteriorate the performance of rubber composites. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132 , 41832.

Rhodanine modified graphene for high-performance elastomer/graphene composites.

Polyrhodanine (PRd) was wrapped onto the surface of halloysite nanotubes (HNTs) through the oxidative polymerization of rhodanine on Fe3+-impregnated-HNTs. The wrapping mechanisms were disclosed. The PRd-HNTs exhibited a prominent reinforcing effect for rubber. With the incorporation of 30phr of PRd-HNTs, the tensile strength was increased by almost 8-fold, and the modulus (at 300% strain) was increased by 257% compared to neat SBR. More strikingly, with only 2.9wt.% of PRd (relative to HNTs), the tensile strength and modulus of the composite were enhanced by 117% and 87%, respectively, suggesting the high efficiency of the modification. Such profound changes in the reinforcement were attributed to the formation of covalent linkages between PRd-HNTs and rubber through the participation of PRd-HNTs in curing process. In view of the versatility of PRd-wrapping procedure, this method offers significant insight into the interfacial design of rubber nanocomposites consisting of nonpolar matrices and inorganic reinforcements.

Incorporating dynamic covalent bonds (DCBs) into elastomers provides a seminal solution for the upcycling of traditional thermoset elastomers. Recently, engineering a multiphase network with various cross-linking uniformity and phase structures has been proven to be an effective strategy to overcome the bottleneck of continuous and high-throughput recycling (e.g., extrusion reprocessing) of vitrimeric elastomers. However, all of the relevant studies only focused on revealing the influences of network structures on the macroscopic properties of the systems. As for the microscopic mechanism of the multiphase network at the molecular level, it is still lacking. Herein, based on coarse-grained molecular dynamics (CGMD) simulation, a modeled DCBs-cross-linked elastomer with a multiphase network was established, which was subsequently subjected to in situ tensile or shear forces to simulate the evolution of local chain segment motion and stress/strain distributions in various microregions of the network under the complex extrusion/injection force field. The results indicate that phase domains with different cross-link densities feature distinct chain segment motion behavior and local stress/strain distribution evolution during tensile/shear deformation, and the interfacial phase exhibits significant high stresses. Therefore, incorporating heterogeneously cross-linked multiphase networks into elastomeric vitrimers can enable the system to have significant network reinforcement and unique interfacial stress amplification effects, which are critical for determining extrusion/injection reprocessability. Therefore, we envisage that the present study can provide a molecular-level theoretical explanation for the extrusion/injection reprocessability of multiphase elastomeric vitrimers, thereby guiding the rational network/performance design of these seminal materials.

No abstract is provided for this article.

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.

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.

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.

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.

The development of efficient electrocatalyst is one of the effective ways to speed up the efficiency of water electrolysis. In this work, we prepared a nested-like Ce-doped CoP nanowires catalytic material on carbon cloth by simple hydrothermal and phosphating methods. After adjusting the doping ratio of Ce, the doping ratio (Ce/W = 6%) with the best performance was obtained and named as Ce-CoP NWs/CC. The Ce-CoP NWs/CC exhibits preeminent electrocatalytic activity with low overpotentials with 80 and 290 mV at 10 mA cm -2 for HER and OER, respectively. Moreover, the Ce-CoP NWs/CC electrocatalyst also exhibits excellent electrochemical performance in overall water splitting with a low voltage of 1.506 V at 10 mA cm -2 , outperforming many reported electrocatalysts. This work provides a feasible electrocatalytic material for the introduction of rare earth elements into water electrolysis.

Aiming at high-strength damping elastomers, the pre-cross-linked sliding graft copolymer (SGC) is incorporated into a nitrile rubber (NBR). The microstructure characterizations reveal that SGC phase is dispersed in NBR matrix fairly uniformly with a distinct interphase. As SGC content increases, the loss factor of SGC/NBR blends gradually increases. The improved damping properties of SGC/NBR blends are attributed to the intrinsic high damping characteristics of SGC and the formed interfacial hydrogen bonds. In addition, the mechanical properties of SGC/NBR blends are unexpectedly improved. The tensile strength of SGC/NBR (20/100) is increased by 170%, comparing to that of neat NBR. The significantly increased tensile strength is ascribed to the increased orientation of NBR chains, because of the "pulley effect" of SGC and the successive rupture/reassociation of interfacial hydrogen bonds. The high damping and mechanical properties of SGC/NBR blends make them potential materials for use in isolation rubber bearings applications.