Publications

Phase-Separated Elastomers with Interfacial Dynamic Cross-Links: Reconciling the Modulus–Toughness Conflict While Integrating Recyclability and Creep Resistance

The effect of ammonium citrate on CoP/CC morphology and its electrocatalytic hydrogen evolution performance

The development and improvement of new transition metal-based catalysts to replace Pt/C electrodes in electrolytic water hydrogen evolution has attracted much attention.In this work, we used ammonium citrate as additive, mixed with cobalt nitrate, through hydrothermal and phosphating methods to get supported on carbon cloth catalyst with new morphology (referred to as E380-CoP/CC, E380 stands for ammonium citrate). Benefit from the dense and fine nanosheet structure,compared with cobalt phosphating alone, the catalyst E380-CoP/CC has a significant improvement in hydrogen evolution performance. In 1 M KOH, the overpotential is 57 mV at the current density of 10 mA cm−2, and the Tafel slope is only 40 mV dec-1, which is very close to the hydrogen evolution performance of Pt/C electrode. In addition, the catalyst has favorable stability and superior hydrogen evolution performance after undergoing CV 2000 cycles and 48 h i-t test. This work offers a reliable idea for realizing electrolytic water hydrogen evolution technology with high efficiency and energy saving.

Organic-inorganic hybrid mineral-reinforced elastomer toward the combination of toughness and ultralow hysteresis

Reinforcing and Flame-Retardant Effects of Halloysite Nanotubes on LLDPE

Halloysite nanotubes (HNTs) were used to compound with linear low density polyethylene (LLDPE) to prepare composites with better mechanical properties and higher flame retardancy. The PE graft was used as interfacial modifier in the LLDPE/HNTs composites. HNTs were showed to be a promising reinforcing and flame retardant nano-filler for LLDPE. The mechanical properties and flame retardancy as well as thermal stability of the composites can be further enhanced by the addition of the graft copolymer. Morphological observation revealed that the graft copolymer could facilitate the dispersion of HNTs in LLDPE matrix and enhance the interfacial bonding.

The influence of molybdenum disulfide nanoplatelets on the dispersion of nano silica in natural rubber composites

The dispersion of nanofiller in polymer composites is critical in governing the ultimate performances. Present study aimed to improve the dispersion of silica in elastomeric materials based on natural rubber (NR) composites using the nanoplatelets of molybdenum disulfide (MoS2), a graphene-like layered inorganic. NR latex was co-coagulated with MoS2 suspension to form NR/MoS2 compounds (1∼5phr). Then silica (30phr) was incorporated into NR/MoS2 compounds, followed by curing with sulfur, to obtained NR/MoS2/silica composites. The dispersion state of silica in the composites was examined by TEM and the effects of MoS2 on the performance of the composites were investigated. It was found that a small amount of MoS2 nanoplatelets significantly improved the silica dispersion. Consequently, the static and dynamic mechanical properties of the crosslinked natural rubber materials were greatly enhanced. The improved dispersion of silica is associated with charge transfer interaction, giving rise to electrostatic repulsion among silica.

Interface Coupling in Rubber/Carbon Black Composites toward Superior Energy-Saving Capability Enabled by Amino-Functionalized Polysulfide

Natural rubber/carbon black (NR/CB) composites have found indispensable application in aircraft tires. Interfacial modification of NR/CB composites for acquiring uniform CB dispersion and strong interfacial adhesion is a persistent and challenging theme, as it is a prerequisite to improve comprehensive mechanical properties and decrease energy loss of the composites under dynamic deformations. In this work, we reported the use of an amino-functionalized polysulfide (PDAS) synthesized by inverse vulcanization of sulfur and m-phenylenediamine as a novel interfacial modifier in NR/CB composites. Specifically, the amino of PDAS can react with the carboxyl groups on the CB surface, meanwhile the polysulfide chains of PDAS can react with rubber chains, enabling the crosslinking of NR and establishment of a molecular bridge between NR and CB. The influences of PDAS dosages on CB dispersion and interfacial adhesion are revealed, and their correlations with composite properties are discussed. Compared with the unmodified counterpart, CB dispersion is greatly improved and interfacial adhesion is significantly enhanced in the PDAS-modified composite having an identical crosslink density, leading to remarkably decreased hysteresis loss. In addition, PDAS can significantly resist thermal-oxidative aging of the composites due to its radical scavenging activity.

Coating polyrhodanine onto boron nitride nanosheets for thermally conductive elastomer composites

Boron nitride nanosheets (BNNSs) have captured much attention in the fabrication of thermally conductive and electrically insulating polymer-based composites. However, inert surface chemistry of BNNSs largely hampers their applications in polymer composites. Herein, we report a facile approach for the fabrication of elastomer/BNNSs composites with high thermal conductivity. BNNSs were first wrapped by polyrhodanine in water to form the polyrhodanine@BNNSs nanostructure (PRh-BNNSs) and then compounded with styrene-butadiene rubber to form the elastomer composites. Due to the unique curing reactivity of polyrhodanine, strong interfaces were formed in the resulting elastomer composites. Accordingly, the SBR/PRh-BNNSs composites exhibited unique combination of high mechanical properties and high thermal conductivity. Importantly, the orientation of BNNSs in the elastomer led to further increase in thermal conductivity. Overall, the present work offers a new route for the design of thermally conductive elastomers through the combination of efficient interfacial modification and filler organization.

Interfacial structure and performance of rubber/boehmite nanocomposites modified by methacrylic acid

Methacrylic acid (MAA) is investigated as a novel in situ interfacial modifier for styrene-butadiene rubber (SBR)/boehmite (BM) composite via a direct blending method. The reaction mechanism for the modification was revealed to be the BM/MAA coordination and MAA/rubber grafting reaction. The substantiated BM/MAA coordination can improve the dispersion of BM in rubber matrix. It is illustrated that the ultimate mechanical performance and interfacial interaction are significantly enhanced by the in situ modification. The strong interaction between BM and SBR and the improved dispersion of BM in the rubber matrix are responsible for the largely enhanced mechanical properties.

Significant Trends in Rubber Research Driven by Environment, Resource, and Sustainability

Liquefied Graphene Oxide with Excellent Amphiphilicity

A new route for liquefying graphene oxide (GO) into supramolecular ionic liquid (SIL) was proposed by the grafting of chloroacetic acid and the subsequent neutralization of carboxy groups with monofunctionalized polyetheramine (Jeffamine 2070). The rheological measurements verified its viscoelastic and liquid-like behavior. The peculiar phenomenon was mainly attributed to the formation of ionic bonds between the corona of chloroacetic acid and the canopy of Jeffamine. This type of highly viscous GO-based liquid possesses excellent amphiphilicity.

Renewable conjugated acids as curatives for high-performance rubber/silica composites

Renewable conjugated acids effectively cure epoxidized diene-based rubber into a high-performance elastomer, in the absence of any toxic additives.

Drying induced aggregation of halloysite nanotubes in polyvinyl alcohol/halloysite nanotubes solution and its effect on properties of composite film

No abstract is provided for this article.

Uniaxial Stretching-Induced Alignment of Carbon Nanotubes in Cross-Linked Elastomer Enabled by Dynamic Cross-Link Reshuffling

The fascinating properties of carbon nanotubes (CNTs) make them highly promising in fabricating polymer composites. Yet, the property enhancements of polymer/CNTs composites remain far behind the theoretical predictions. A critical issue to resolve this dilemma is to align CNTs in polymer matrices. Thus far, the state of art approaches to create CNT alignment either require complicated preparation processes and specific apparatuses, or is limited to thermoplastic polymers. Here, inspired by the network rearrangement ability of vitrimer in the solid state, we bring forth a facile methodology to align CNT in covalently cross-linked polymers by uniaxially stretching dynamic. Specifically, dynamic boronic ester bond-cross-linked epoxidized natural rubber/CNTs vitrimer composites with randomly dispersed CNTs are prepared, which are able to rearrange the network topologies and release stress at elevated temperatures through boronic ester transesterifications. The alignment of CNTs is performed by the uniaxial stretching of the composites and subsequent cross-link reshuffling at elevated temperatures, which results in anisotropic composites with remarkably enhanced mechanical properties and reduced electrical conductivity along the stretching direction. Furthermore, the mechanical properties of the composites can be readily adjusted by changing the applied strain, relaxation time and temperature due to the modulated CNT alignment degree. With this example, we envisage that this work offers a conceptual and facile approach to align anisotropic fillers in covalently cross-linked polymers.

N-Doped Hollow Nanofibers Loaded with Ruconi Ternary Alloy as an Efficient Catalyst for Hydrogen Evolution Reaction

No abstract is provided for this article.

Polymer‐modified halloysite composite nanotubes

A natural clay halloysite, which is a kind of aluminosilicate with a predominantly nanosized hollow tubular structure, was modified by polymers achieving polymer‐halloysite composite nanotubes. Polymer chains can grow from both interior and exterior surfaces of the halloysite nanotubes by atom transfer radial polymerization (ATRP). Eventually, the composite nanotubes were evolved to a core‐shell coaxial structure after the interior cavity was fully covered by the polymer. After dissolution of the halloysite template, polymeric nanotubes and nanowires were derived. The composition could be controlled from polymer to carbon after being treated at high temperature. The idea can be extended to a cast halloysite fabric resulting nonwoven composites, which had some interesting wettability. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

Design of next-generation cross-linking structure for elastomers toward green process and a real recycling loop

Currently adopted cross-linking methods in rubber industry are suffering from variable persistent issues, including the utilization of toxic curing packages, release of volatile organic compounds (VOCs) and difficulties in the recycling of end-of-life materials. It is of great importance to explore a green cross-linking strategy in the area. Herein, we report a new “green” strategy based on hydrolyzable ester cross-links for cross-linking diene-typed elastomers. As a proof of concept, a commercial carboxylated nitrile rubber (XNBR) is efficiently cross-linked by a bio-based agent, epoxidized soybean oil (ESO), without any toxic additives. ESO exhibits an excellent plasticization effect and excellent scorch safety for XNBR. The cross-linking density and mechanical properties of the ESO-cured XNBR can be manipulated in a wide range by changing simply varying the content of ESO. In addition, zinc oxide (ZnO) performs as a catalyst to accelerate the epoxide opening reaction and improve the cross-linking efficiency, serving as reinforcement points to enhance the overall mechanical properties of the ESO-cured XNBR. Furthermore, the end-of-life elastomer materials demonstrate a closed-loop recovery by selectively cleaving the ester bonds, resulting in very high recovery of the mechanical performance of the recycled composites. This strategy provides an unprecedented green avenue to cross-link diene elastomers and a cost-effective approach to further recycle the obtained cross-linked elastomers at high efficiency.

Joule heating synthesis of PtNiCo nanoparticles-loaded carbon fibers for hydrogen evolution reaction

Sustainable shape memory polymers based on epoxidized natural rubber cured by zinc ferulate via oxa-Michael reaction

Although various shape memory polymers (SMPs) or diverse applications have been widely reported, the SMPs based on rubbers have been rarely realized due to the low triggering temperature of rubbers. In another aspect, the SMPs based on sustainable substances are highly desired for the growing shortage in fossil resources. In the present study, we accordingly developed the sustainable SMPs with tunable triggering temperature, based on natural rubber (NR) and ferulic acid (FA) as the raw materials. Specifically, the SMPs are based on a crosslinked network of epoxidized natural rubber (ENR) crosslinked by in situ formed zinc ferulate (ZDF) via oxa-Michael reaction. The excellent shape memory effect (SME) is found in these SMPs, as evidenced by the high fixity/recovery ratio and the tunable triggering temperature. With the incorporation of natural halloysite nanotubes (HNTs), the stress and recovery rate of the SMPs are found to be tunable, which widens the application of this kind of SMPs. The combination of adoption of sustainable raw materials, and the excellent and tunable SME makes these SMPs potentially useful in many applications, such as various actuators and heat-shrinkable package materials.