Publications

Structure evolution of carbon black under ionic-liquid-assisted microwave irradiation

The interactions between the carbon black (CB) and the ionic liquid (IL), 1-butyl-3-methyl-imiazolium hexafluorophosphate ([BMIM+][PF6 −]), are firstly examined. The CB, mixed with the IL via simple blending, is then subjected to microwave (MW) irradiation to prepare the modified CB. The structure evolutions of the modified CB such as the microcrystalline structure and surface chemistry are revealed by Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and pore analysis. After mixing but before MW irradiation, the microcrystalline arrangement of CB turns to be more ordering and microcrystalline size (La) to be a little bigger but with a limited degree. Under MW irradiation, the IL undergoes severe decomposition. The combination of localized high temperature (proposed to be higher than 425°C) and the decomposition of the IL leads to substantial structure changes of the CB. The graphitization of the CB surface, the disordering of the microcrystalline and the decrease in La are disclosed. In addition, compared with the untreated CB, the CB treated with IL-assisted MW irradiation is found to have much higher volume of the smaller mesopore.

Modifying properties and endurance of CoP by cerium doping to enhances overall water splitting in alkaline medium

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 is 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.

Mechanically Robust and Recyclable EPDM Rubber Composites by a Green Cross-Linking Strategy

Covalently cross-linked rubbers are indispensable in many important fields due to their unique entropic elasticity. For rubbers cross-linking, the addition of toxic curing agents, release of toxic volatile organic compounds (VOCs), and recycling of waste rubber are three important issues. A combination of green curing chemistry and efficient recycling into commercial polyolefin rubbers is of great importance. Herein, we demonstrate a facile and promising way to incorporate dynamic covalent bonds into ethylene-propylene-diene monomer (EPDM)/carbon black (CB) composites. The epoxy-functionalized EPDM (e-EPDM) was prepared using an in situ epoxidation reaction and then cured with biobased decanedioicacid (DA) through the reactions between the epoxy groups in e-EPDM and the carboxylic groups in DA. Because of the existence of exchangeable β-hydroxyl ester, the covalently cross-linked networks in e-EPDM/CB composites were able to rearrange their topological structure at high temperature, endowing the composites with recycled and reshaped abilities. More importantly, the recycled e-EPDM/CB composites still exhibit outstanding mechanical properties which can meet the needs of practical applications. This strategy may provide an efficient, green, and sustainable way to address the problems brought from rubbers cross-linking.

Bioinspired design of elastomeric vitrimers with sacrificial metal-ligand interactions leading to supramechanical robustness and retentive malleability

Most elastomeric vitrimers suffer from mechanical weakness in practical applications. Inspired by the development of strong and tough biomaterials relying on sacrificial bond-detachment mechanisms, herein we describe the biomimetic design of elastomeric vitrimers with mechanical robustness, preservable malleability, and recyclability by engineering sacrificial metal-ligand coordination bonds into exchangeable networks. In particular, we use a commercially available metal complex, aluminum acetylacetonate (Al(acac)3), to catalyze cross-linking based on the silylation reaction between hydroxylated natural rubber and hydrosilanes, thus introducing dynamic silyl ether-based architectures into the rubber matrix. At the same time, the Al3+ ions can interact with the free oxygen-containing moieties on the rubber skeleton, enabling labile Al3+O coordination bonds in the covalent framework to substantially dissipate mechanical energy through reversible bond detachment/reattachment upon deformation. As the organic acetylacetonate ligands of Al(acac)3 can facilitate the dispersion of Al3+ ions in the matrix, incorporating a small amount of organometallic complex (0.68 wt% of elastomer matrix) achieves an unparalleled improvement of the strength, modulus, and toughness of the resulting vitrimers. Moreover, due to their temperature-dependent nature, the Al3+O coordination bonds will partially dissociate at elevated temperatures, which only slightly compromises the topological rearrangements of the silyl ether-based network, but barely affects the reprocessability.

A Novel and Non-Cytotoxic Self-Healing Supramolecular Elastomer Synthesized with Small Molecular Biological Acids

A novel and non-cytotoxic self-healing supramolecular elastomer (SE) is synthesized with small-molecular biological acids by hydrogen-bonding interactions. The synthesized SEs behave as rubber at room temperature without additional plasticizers or crosslinkers, which is attributed to the phase-separated structure. The SE material exhibits outstanding self-healing capability at room temperature and essential non-cytotoxicity, which makes it a potential candidate for biomedical applications.

Hydrogen bond-containing oligomer as a facile interfacial mediator in rubber/silica composites

Silica is one of the most important reinforcements in the rubber industry due to its indispensable applications in green tires. However, the significant difference in polarity between conventional diene rubber and silica generally results in poor silica dispersion and, hence, considerably compromises the overall performance of the composites. Herein, a poly (hydroxyethyl methacrylate) oligomer was synthesized via living radical polymerization using disulfiram as an iniferter. Upon thermal activation, the oligomer can further divide into macroradicals that are capable of directly grafting onto the unsaturated moieties in the rubber skeleton. Therefore, the pendant ester and hydroxyl functionalities can interact with silanol groups on the silica surface through interfacial hydrogen bonding, which significantly improves the interfacial interaction and facilitates the dispersion of silica. Accordingly, incorporating a small amount of oligomer (less than 3.5 wt%) can achieve a remarkable improvement in the tensile modulus and rolling and wet skid resistances of the obtained composites. We envisage that the present reactive oligomer can provide an effective strategy toward in situ modification of the rubber skeleton, which also has significant potential to optimize the static and dynamic performance of rubber/silica composites for tire tread applications.

Joule Heating Synthesis of Ptnico Nanoparticles-Loaded Carbon Fibers for Hydrogen Evolution Reaction

Mechanical and rheological properties of poly(lactic acid) toughened by bio‐based thermoplastic polyamide elastomer

Abstract Polylactic acid (PLA)/thermoplastic polyamide elastomer (TPAE) blends were prepared by melt‐compounding on a two‐roll mill. The effects of the TPAE content on the mechanical properties, thermal stability, and rheological behaviors of the blends were fully investigated. With the incorporation of 30 wt% TPAE, the elongation at break and impact strength of the PLA/TPAE blend were increased by 34 times and 3.5 times as compared with the neat PLA, respectively. The improved toughness and tensile ductility were contributed to by the stress whitening and shear plastic deformation, which can absorb energy when subjected to external work. The thermal stability of the PLA/TPAE blends was slightly decreased with the incorporation of the TPA. The dynamic mechanical analysis showed that the blends possessed better elasticity and toughness at low temperatures, and the presence of the TPAE promoted the cold crystallization of the PLA. The rheological behaviors demonstrated that TPAE was compatible with PLA, and obvious chain entanglement occurred between them, resulting in a heterogeneous structure with fine phase separation. Highlights TPAE ensured the overall biodegradability of the toughened PLA. TPAE enhanced the elongation at break and impact strength of the PLA blend. The toughening mechanism and rheological properties were investigated.

Promoted strain-induced-crystallization in synthetic cis-1,4-polyisoprene via constructing sacrificial bonds

In order to simulate the effect of non-rubber components on strain-induced crystallization (SIC) in natural rubber (NR), sacrificial metal-ligand bonds are incorporated, for the first time, into cis-1,4 polyisoprene cured by sulfur. The incorporation of sacrificial bonds is found to bring in much smaller onset strain for SIC and higher crystallinity compared with the cis-1,4 polyisoprene with sulfide crosslinks only. Accordingly, the striking improvements in tensile modulus and fracture toughness are achieved. The present work contributes to significant insights for mimicking NR outstanding properties in synthesized cis-1,4 polyisoprene and affords new technological route in improving the mechanical properties of synthesized polyisoprene alternative to the nanofilling.

Rational design of covalent interfaces for graphene/elastomer nanocomposites

The energy loss of tires during service is closely related to the hysteresis of tire tread, which is governed by the dispersion and interface of the elastomer nanocomposites. However, traditional undeformable spherical fillers have approached a bottleneck in regulating the viscoelasticity and lowering the hysteresis loss. Herein, the designed covalent interface in the graphene/elastomer nanocomposite maximizes the reinforcement of the nanomaterial as well as minimizes the dynamic energy loss. The reinforced interfacial interaction, an ultralow percolation threshold of tensile strength and high reinforcement synergistically benefit these nano-organized rubber nanocomposites. The energy losses under dynamic loading are largely suppressed in this material, due to the reduced nano-scale frictions. The developed graphene/elastomer nanocomposites are applied to typical dynamic rubber product - auto tires, and the tests indicate that these tires possess energy efficiency close to the highest “A-grade”, which gave great economic and environmental improvements. The critical role of interface structure in the performance of the elastomer nanocomposites was revealed and new design strategy for low dynamic energy losses in rubber products was suggested.

Nanofibrous membranes with hydrophobic and thermoregulatory functions fabricated by coaxial electrospinning

In the face of changing outdoor environments, it is necessary for us to develop advanced textiles with thermal regulation and hydrophobic properties. In order to create a fabric with both temperature control and waterproof properties, the study adjusted the ratio of polystyrene (PS) and polyvinylidene fluoride (PVDF) to produce nanofiber membranes with excellent morphology and dirt resistant properties. Furthermore, the hydrophobicity of the nanofibers was further improved by adding SiO 2 to the spinning solution. Based on this, a core solution of octadecane (Oct) was used to give it thermal regulation functionality through coaxial electrospinning technique. The resulting composite nanofiber membrane exhibited excellent hydrophobicity and thermal regulation performance. The measurement results obtained from Differential Scanning Calorimetry (DSC) indicate that the maximum Oct encapsulation rate of the PS/PVDF/SiO 2 @Oct nanofiber membrane is 58.36%. The latent heat of the composite nanofiber membrane is 148.84 J/g, and the water contact angle (WCA) is 135°. The multifunctional composite nanofiber has great potential for applications in outdoor protective clothing and outdoor electronic device protection.

Interphase Percolation Mechanism Underlying Elastomer Reinforcement

Glassy interphase has been claimed to be of vital importance for mechanical reinforcement of elastomer nanocomposites (ENCs), but the evolution of interphase topology in correlation to reinforcement percolation remains uncertain. Here, an accurate interfacial regulation strategy upon implementing an interphase percolation mechanism is exploited to realize percolation of mechanical performance toward striking elastomer reinforcement. Architecture design of interfacial metal–ligand bridges accomplishes firm anchoring between elastomer skeleton and carbon nanodots, leading to the formation of interfacial metal-enriched regions. The volume fraction of the interfacial region systemically enlarges upon increase of interfacial bridges, which finally overlaps with neighboring domains to form a penetrating interphase. The topological evolution of the interfacial region is quantitatively monitored upon small-angle X-ray scattering and dielectric measurements, which exhibits a similar percolation behavior in sync with that of macroscopic mechanical performance. Furthermore, the interphase exhibits much slower relaxation dynamics than in bulk polymer, which significantly improves the network rigidity and hence accounts for the prominent elastomer reinforcement. This investigation corroborates that the formation of penetrating interphase may be an executable mechanism to induce the reinforcement percolation of ENCs. We further envision that the implementation of interphase percolation mechanism can be a universal avenue to afford rationalized optimization of ENCs.

Reversible plasticity shape memory polymers: Key factors and applications

Reversible plasticity shape memory (RPSM) polymers have been emerging as new smart materials with distinctions compared with conventional SMPs, such as easier shaping programming, stronger recovery stress, and higher recovery strain. For purposeful control of the structure, and therefore the physical and mechanical properties, a full understanding of the deformation habits of such materials under different conditions is essential. This perspective provides the context as to how the deformation temperature and fixing conditions influence the fixity and recovery behavior of RPSM polymers and what are the optimized conditions for RPSM. We hope that this will afford useful information for fabricating RPSM polymers with better memory properties and promote the technical development of new design methods of such materials for advanced applications © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54 , 1295–1299

Studies on NBR-ZDMA-OMMT Nanocomposites Prepared by Reactive Mixing Intercalation Method

Two kinds of nanocomposites of nitrile-butadiene rubber (NBR), zinc methacrylate (ZDMA) and organomontmorillonite (OMMT), NBR-ZDMA-HMMTand NBR-ZDMA-USMMT, were prepared by the reactive mixing intercalation method with ZDMA and two kinds of organomontmorillonite, hexadecyltrimethylammonium bromide modified montmorillonite (HMMT) and unsaturated chemical modified montmorillonite (USMMT). The structure and properties of the nanocomposites were investigated by X-ray diffraction, transmission electron microscopy, differential scanning calorimetry and determination of crosslinking density and mechanical properties. The results showed that the interlayer galleries of HMMT and USMMT were enlarged as ZDMA polymerized in situ in rubber matrix and between the interlayer of the silicates. The layered silicates were dispersed disorderly in rubber matrix at a nanometer level. The crosslinking density of the NBR vulcanizates was increased by the addition of ZDMA and HMMT or USMMT. The glass transition temperatures of the NBR-ZDMA-OMMT nanocomposites were higher than that of the neat NBR. The mechanical properties of the NBR-ZDMA-HMMTand NBR-ZDMA-USMMT nanocomposites are remarkably superior to those of the neat NBR vulcanizate.

Effects of Thermal and UV-induced Grafting of Bismaleimide on Mechanical Performance of Reclaimed Rubber/Natural Rubber Blends

No abstract is provided for this article.

Grafting of Polyester onto Graphene for Electrically and Thermally Conductive Composites

Many reported polymer/graphene composites, even some with excellent graphene dispersion, do not possess impressive conductivity, which may be due to the failure in forming interconnected conductive paths. In this work, a kind of bio-based polyester (BE) is synthesized by polycondensation between plant-derived diols and diacids. It is then grafted onto graphene oxide (GO) via the easterification between hydroxyls of BE and carboxyls of GO. Subsequently, the grafted GO is subjected to reduce by vitamin C. Because of the presence of terminal hydroxyl group in both ends of the BE chains and multiple carboxyl groups on GO, the grafts form specific spatial interconnection structure in BE matrix. The resulting BE/graphene composites possess impressive low threshold percolation of electrical conductivity, in combination of high thermal conductivity.

Carbon nanofibers load PtRu alloy self-supporting the preparation of electrode and its application in electrocatalytic hydrogen evolution

New Design of Shape Memory Polymers Based on Natural Rubber Crosslinked via Oxa-Michael Reaction

Shape memory polymers (SMPs) based on natural rubber were fabricated by crosslinking epoxidized natural rubber with zinc diacrylate (ZDA) using the oxa-Michael reaction. These SMPs possessed excellent shape fixity and recovery. The glass transition largely accounted for the fixing of the SMPs temporary shape. Increasing the ZDA content allowed the trigger temperature (20-46 °C) and recovery time (14-33 s) of the SMPs to be continuously tuned. Nanosized silica (nanosilica) was incorporated into the neat polymers to further increase the flexibility and tune the recovery stress. The nanosilica-SMPs exhibited exceptionally high strength in a rubbery state (>20 MPa). The nanosilica-SMPs exhibited high transparency, making them suitable in visible heat-shrinkable tubes.