Publications

Imine bond crosslinked networks with tunable mechanical and dynamic properties are prepared by varying the precursor molecular weight and network crosslinking degree.

Reinforcement is a fundamental issue in rubber science and engineering. Traditionally, rubber reinforcement relies on the incorporation of rigid particles into rubber network or creation of the rubber network with dual-crosslink. However, all these methods inevitably sacrifice the unique elasticity of rubber, which is a shackle toward some crucial applications such as energy-saving tires. In this contribution, a novel strategy of rubber-reinforced rubber (3R) with the combination of significant reinforcement and high elasticity is proposed. With experimental/simulating integrated method, a brand-new reinforcing mechanism for rubber is disclosed, called soft matrix-induced large extensionability of hard rubber (“SMILE-HR”). The soft matrix endows the highly-crosslinked rubber particles (HPs) with the capacity of large extensionablity, so the molecular chains in HPs can be highly oriented and thus obtain high strength during stretching, which are primarily responsible for the dramatic reinforcement of 3R. This skillful combination of these two elastic constituents conquers the stubborn contradiction between reinforcement and elasticity, which is very promising for the engineering rubbers served in dynamic environment.

The synergistic effect of dynamic covalent bond (DCB) multiplicity on the dynamic performance of vitrimeric elastomers is disclosed.

Constructing segregated structure in polymer composites is a particularly effective strategy to improve electrical conductivity by selectively distributing fillers in the interstitial space among isolated polymer domains. However, the segregated composites generally suffer from inferior mechanical properties because the fillers at the interfaces hinder chain diffusion and leads to weak interfacial adherence or defects. In this contribution, we present a facile method to fabricate segregated composites with improved electrical conductivities and mechanical properties by creating molecular bridges across the interfaces among the segregated domains. Specifically, β-hydroxyl ester-crosslinked epoxidized natural rubber (ENR) granules were compounded with the master batch of carboxylated nitrile rubber (xNBR) and carbon nanotubes (CNTs), followed by compression molding. In the resultant composites, CNTs embedded in xNBR phase are distributed along the boundaries of ENR domains, and xNBR can act as binder to bridge the crosslinked ENR granules through the reaction of carboxyl groups with the epoxy groups and β-hydroxyl esters on ENR granule surfaces. As a consequence, the segregated composites exhibit greatly improved electrical conductivity and mechanical properties when comparing to their randomly dispersed counterparts. In addition, the segregated network is able to endure deformations and heal damage without significant loss of the electrical conductivity. The conductive and mechanical properties of the composites are found to be closely related to the morphologies of segregated structure and CNT concentration in the continuous xNBR phase.

High-performance rubbers with low gas permeability have attracted extensive attention due to their wide application. In this work, for the first time, the tortuosity effect is created in unfilled rubbers via heterogeneous cross-linking. The heterogeneously cross-linked rubbers exhibit a sea–island morphology with excellent interfacial interactions in which the dispersed rubber granules (RGs) are densely cross-linked, while the matrix phase is normally cross-linked. The hard RG phases showed low gas permeability, which can not only serve as a rigid yet elastic reinforcement for rubbers but also inhibit the gas permeation in rubbers. The excellent interfacial interactions between the two phases have a pronounced effect on the ultimate performance of rubbers. Surprisingly, the simultaneously improved mechanical performance and the gas barrier property achieved in the heterogeneously cross-linked rubber are competitive with the rubber nanocomposites filled with two-dimensional fillers. It is revealed that the ingenuity of such a heterogeneous design is the tortuosity effect imposed by the dispersed RG phases with low permeability, which makes an additional contribution to the reduction of gas permeability. Accordingly, a modified Nielsen equation was developed to model the gas barrier property of heterogeneously cross-linked rubbers, offering reliable prediction and rational mechanism elucidation of gas permeation for the heterogeneous design. In view of the scale-up capability and universality of this method, we envisage that this work offers a promising avenue, alternative to nanofilling, for preparing the rubbers with excellent gas barrier properties.

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.

Alloying noble metals with abundant transition metals is an effective strategy for preparing cost-effective electrocatalysts for efficient hydrogen evolution reaction. In this study, hollow carbon nanofibers loaded with RuCoNi ternary alloy nanofiber catalysts (RuCoNi/CNFs) were synthesized by coaxial electrostatic spinning and a high-temperature carbonization approach. The interconnected three-dimensional hollow nanofibers, uniformly loaded with RuCoNi alloy nanoparticles, provided a large specific surface area and a hierarchical porous structure to enhance the interaction between the electrolyte and the active sites. Additionally, the hollow structure facilitated active sites exposure, charge transport, and gas diffusion, resulting in excellent HER activity of RuCoNi/CNFs. The overpotential required to achieve a current density of 10 mA cm−2 under alkaline conditions was only 47 mV, outperforming the homemade Pt/C catalyst (54 mV). Moreover, the carbon structure acted as a conductive carrier for efficient electron transfer, protecting the alloy nanoparticles from aggregation and corrosion. The RuCoNi/CNFs demonstrated remarkable stability and durability, maintaining consistent performance even after 100 hours of continuous operation. Importantly, the catalyst also exhibited favorable HER activity (186 mV@100 mA cm−2) at high current density, highlighting its potential for practical applications in large-scale industry.

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.

ABSTRACT To improve the mechanical properties and heat resistance of iron powder cores for inductors, the carbonyl iron powder was insulation‐treated via phosphating and epoxy‐modified bismaleimide resin coating. The addition of epoxy into bismaleimide resin significantly enhanced the magnetic performance, mechanical strength and thermal stability of powder cores. The optimised core exhibited an effective permeability μ e of 25.8 and a quality factor Q of 54.9 at 1 MHz, with a power loss P cv of 510.2 kW·m −3 at 100 kHz/50 mT. The radial crushing strength increased by 102% compared to the core coated with only bismaleimide. After thermal exposure at 155°C for 336 h, the cores coated with epoxy‐modified bismaleimide showed lower reductions in saturation magnetisation and minimal changes in μ e (4.41%), Q (4.96%) and P cv (3.82%), indicating improved heat resistance. Epoxy modification enhanced bismaleimide performance by forming hydroxyl groups through their interaction, creating strong polar bonds with iron powder. The interaction results in a three‐dimensional network structure consisting of rigid and flexible molecular chains. This structure reinforced the mechanical properties and heat resistance of the iron powder core.

The transfer of vitrimer concept to diene-rubber materials can enable these thermosets with thermo-activated malleability and reprocessability. However, there are still significant gaps in the knowledge of introducing dynamic covalent bonds-based networks directly into rubber matrix without the need for elaborated modification of the molecular architecture. Herein, we demonstrate a one-pot approach to prepare covalently cross-linked diene-rubbers by engineering dynamic silyl ether linkages into the networks. Specifically, based on a thermally initiated thiol-ene reaction, silyl ether-based networks were directly achieved through incorporating silyl ether-containing multifunctional thiols (SE-T x ) into commercially available diene-rubber. The mechanical and dynamic behaviors of the resulting networks can be rationally tuned upon the regulation of the content and functionality of SE-T x cross-linkers. In addition, by virtue of the thermal stability of silyl ether linkages, the resulting networks feature with superior creep resistance at moderate temperatures, while the corresponding network rearrangement ability at elevated temperatures is barely affected, enabling the networks with malleability and recyclability.

As the principal reinforcement filler, carbon black (CB) has been used in the rubber industry for over a century. However, the poor dispersity of CB in rubber matrices is still a bottleneck for preparing high-performance CB-filled rubber composites. In this contribution, we utilized the triazolinedione (TAD)-ene click chemistry to introduce the active urazole groups onto the natural rubber (NR) chains. The grafted urazole groups could be converted to the stable urazole radicals through the transformation from rubber macroradicals or under thermal oxidation and then trapped by CB to form the covalent interaction between rubber and CB. The enhanced interfacial interaction greatly improves the dispersion of CB in the NR matrix, leading to a significantly suppressed filler network. With a suitable TAD grafting ratio, the modulus and the wet-traction of NR/CB composite are improved, meanwhile the rolling resistance is strikingly reduced, which is very promising for the application of energy-saving tires.

The dispersion of filler and interfacial interaction are crucial in determining the properties of rubber composites. Aiming to improve the dispersion and filler–rubber interaction, we introduce rubber graft bearing oniums in a rubber/silica composite. To fulfill this goal, the graft, which is prepared via thio‐ene click reaction between 1‐methylimidazolium mercaptopropionate (MMP) and the pendent vinyl groups of a solution‐polymerized styrene‐butadiene rubber (SSBR), is introduced into the silica‐filled styrene‐butadiene rubber (SBR) composite. The dispersion of silica and interfacial interaction are improved via hydrogen bonding interaction. Moreover, the graft exhibits catalytic effect toward the silanization, which can improve interfacial interaction in the composites with bis [3‐(triethoxysilyl) propyl] tetrasulfide. With 2 phr of the graft, the tensile modulus (stress at 300% strain) is increased by 18% and the abrasion loss is decreased by 31%. This study opens a new attempt to improve the filler dispersion and filler–rubber interaction in the composites with onium‐bearing polymers. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136 , 48243.

Transition metal phosphides (TMPs) are a promising catalyst material for the hydrogen evolution reaction (HER). In this study, we introduced inexpensive red phosphorus (P4) into a homogeneous solution as a phosphorus source. Using the electrostatic spinning technique combined with high temperature carbonization, we successfully prepared self-supported carbon nanofibers doped with nitrogen (N) and loaded with ruthenium (Ru)-modified cobalt phosphide (Co2P) nanoparticles catalysts (Ru@Co2P/CNFs). The Ru@Co2P phosphide nanoparticles were evenly distributed on the surface of the carbon fibers, forming a three-dimensional network structure. The synergistic effect between the Ru and Co2P systems resulted in excellent catalytic activity and stability for the hydrogen evolution reaction in alkaline solutions. The N-doped conducting carbon matrix and large specific surface area of the active sites contributed to this enhanced performance. The Ru@Co2P/CNFs catalysts only required an overpotential of 48 mV at a current density of 10 mA cm−2, outperforming the noble metal platinum/carbon (Pt/C) catalysts, which required an overpotential of 52 mV. Furthermore, the Ru@Co2P nanoparticles were protected by a carbon layer, preventing catalyst corrosion during long-term operation. The HER performance of the Ru@Co2P/CNFs catalysts remained stable even after 40 h of continuous operation, demonstrating their long-lasting stability. This research introduces a new approach to developing cost-effective and highly active self-supported network-structured phosphide catalysts.

The nanocomposites of nitrile–butadiene rubber (NBR) and organo‐montmorillonite modified by hexadecyltrimethyl ammonium bromide (HMMT) were prepared by the reactive mixing intercalation method in the presence of the resorcinol and hexamethylenetetramine complex (RH). The structure of the NBR–RH–HMMT nanocomposites was characterized by XRD, TEM, FTIR, determination of crosslinking density, and so on. The results showed that the d‐ spacing of HMMT increased substantially with RH addition and the layers of HMMT were dispersed in rubber matrix on a nanometer scale. The mechanical properties of the NBR–RH–HMMT nanocomposites were far superior to those of NBR–HMMT composites, and the glass transition temperature of NBR–RH–HMMT nanocomposite was higher than that of NBR. The reactive mixing intercalation method by introducing RH could enhance the interface combination between the rubber and the organoclay through the interactions of RH with NBR and modified clay. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1905–1913, 2006

We reported the use of an inverse vulcanised polysulfide (SP) as an intelligent interfacial modifier in the NR/CB composites to remarkably decrease the hysteresis loss by enhancing the interfacial adhesion and improving CB dispersion. Specifically, SP synthesized by the bulk copolymerization of sulfur and styrene was grafted onto CB surface by trapping the sulfur radicals generated from SP, and the grafted polysulfides can participate in the crosslinking reaction with NR, which greatly improves CB dispersion and strengthens interfacial adhesion in the composites. As a consequence, the rolling resistance and heat build-up of the modified composites are remarkably decreased, showing great advantages in tire application in term of reducing fuel consumption and extending service life.