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Theoretically, separating the positive and negative charge centers of the chain segments of dielectric elastomers (DEs) is a viable alternative to the conventional decoration of chain backbone with polar handles, since it can dramatically increase the dipole vector and hence the dielectric constant (ε') of the DEs while circumvent the undesired impact of the decorated polar handles on the dielectric loss (tan δ). Herein, a novel and universal method is demonstrated to achieve effective separation of the charge centers of chain segments in homogeneous DEs by steric hindrance engineering, i.e., by incorporating a series of different included angle-containing building blocks into the networks. Both experimental and simulation results have shown that the introduction of these building blocks can create a spatially fixed included angle between two adjacent chain segments, thus separating the charge center of the associated region. Accordingly, incorporating a minimal amount of these building blocks (≈5 mol%) can lead to a considerably sharp increase (≈50%) in the ε' of the DEs while maintaining an extremely low tan δ (≈0.006@1 kHz), indicating that this methodology can substantially optimize the dielectric performance of DEs based on a completely different mechanism from the established methods., (© 2024 Wiley‐VCH GmbH.)

Roxadustat (FG-4592) is a hypoxia-inducible factor prolyl hydroxylase inhibitor (HIF-PHI) prescribed to patients with low hemoglobin associated with chronic kidney disease. Due to the various HIF-mediated adaptive responses, FG-4592 has attracted significant interest for therapeutic use against various diseases. However, the clinical application of Roxadustat remains limited due to a lack of understanding of its underlying mechanisms. Herein, we performed label-free quantitative liquid chromatography with tandem mass spectrometry (LC-MS-MS) proteomics and un-targeted metabolomics to study the protein and metabolite alterations in the urine of renal anemia patients before and after Roxadustat therapy. The results were validated by parallel reaction monitoring (PRM). A total of 46 proteins (including 15 upregulated and 31 downregulated proteins) and 207 metabolites were significantly altered after Roxadustat treatment in urine samples obtained from renal anemia patients. Then, the altered proteins were further validated by PRM. Finally, proteomics combined with metabolomics analysis revealed that the Ras signalling pathway, cysteine and methionine metabolism, arginine and proline metabolism, and cholesterol metabolism were the main pathways altered by Roxadustat treatment. The multi-omics analysis revealed that Roxadustat could alter the protein expression and reverse the potential metabolic changes to exert hypotensive, lipid metabolic regulation, and renoprotective effects in clinical practice.

Upcycling of cross-linked rubbers is pressing. The introduction of dynamic covalent bonds into the networks is a popular tactic for recycling thermosetting polymers, but it is very challenging to integrate engineering performance and continuous yet stable reprocessability. Based on traditional rubber formulations, herein, a straightforward strategy is presented for constructing a skeletal network (SN) through interfacial crosslinking and percolation of rubbery granules in a rubber matrix. Rapid exchange reactions involving dynamic interfacial sulfides realize repeated "fragmentation and healing" in the solid-state and consequent reconfiguration of the SN topology of the elastomer, thus endowing the resultant SN elastomer with continuous yet stable re-extrudability. These SN elastomers with hierarchical structures exhibit high gel contents, high resilience, low creep, and reinforcibility competitive to traditional vulcanizates. Specifically, SN elastomers exhibit better overall performance than commercial thermoplastic vulcanizates (TPVs) materials. Overall, a new concept of thermoplastic vulcanizates is proposed, which will promote the sustainable development of rubbers., (© 2023 Wiley-VCH GmbH.)

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.

Background: Tumor glycolysis is a critical event for tumor progression. Docetaxel is widely used as a first-line drug for chemotherapy and shown to have a survival advantage. However, the role of docetaxel in tumor glycolysis remained poorly understood., Methods: The effect of Docetaxel in tumor glycolysis and proliferation were performed by CCK-8, Western blotting, real-time PCR, glucose, and lactate detection and IHC. ChIP and luciferase assay were used to analyze the mechanism of Docetaxel on Smad3-mediated HIF-1α transactivity., Results: In this study, we showed that docetaxel treatment led to a significant inhibition of cell proliferation in prostate cancer cells through PFKP-mediated glycolysis. Addition of lactate, a production of glycolysis, could reverse the inhibitory effect of docetaxel on cell proliferation. Further analysis has demonstrated that phosphorylation of Smad3 (Ser213) was drastically decreased in response to docetaxel stimulation, leading to reduce Smad3 nuclear translocation. Luciferase and Chromatin immunoprecipitation (ChIP) analysis revealed that docetaxel treatment inhibited the binding of Smad3 to the promoter of the HIF-1α gene, suppressing transcriptional activation of HIF-1α. Moreover, ectopic expression of Smad3 in prostate cancer cells could overcome the decreased HIF-1α expression and its target gene PFKP caused by docetaxel treatment. Most importantly, endogenous Smad3 regulated and interacted with HIF-1α, and this interaction was destroyed in response to docetaxel treatment. What's more, both HIF-1α and PFKP expression were significantly reduced in prostate cancer received docetaxel treatment in vivo., Conclusion: These findings extended the essential role of docetaxel and revealed that docetaxel inhibited cell proliferation by targeting Smad3/HIF-1α signaling-mediated tumor Warburg in prostate cancer cells. Video Abstract., (© 2022. The Author(s).)

Background: Roxadustat is a new oral anti-renal anemia medication that works by stabilizing hypoxia-inducible factor (HIF) which can activate the expression of more than 100 genes in addition to genes related to anemia. However, the more potential molecular targets of roxadustat are not completely clear. Therefore, it is essential to further reveal its molecular targets to guide its clinical applications., Methods: We performed label-free quantification and LC-MS/MS to study the proteomic alterations in serum exosome of renal anemia patients before and after roxadustat therapy. Results were validated by PRM., Results: A total of 30 proteins were significantly changed after treatment with roxadustat. Among these proteins, 18 proteins were up-regulated (and 12 were down-regulated). The results are statistically significant (P < 0.05). Then, we validated the result by PRM, the results confirmed that TFRC, HSPA8, ITGB3, COL1A2, and YWHAZ were markedly upregulated, while ITIH2 and CFH were significantly downregulated upon treatment with roxadustat., Conclusions: TFRC and HSPA8 could be an important target of the action of roxadustat, and roxadustat may increase cardiovascular risk through its influence on platelet activation. Our results provide a theoretical basis for its wider clinical application and preventing expected side effects., (© 2022. The Author(s).)

Electrically and thermally conductive polymer composites are extensively used in our daily life. It is of great significance to fulfill the conductivity requirement while maintaining desirable mechanical performance. An efficient solution to achieve this goal is to construct segregated structures in polymer composites by confining fillers into the interstitial areas among polymer domains. Thus far, it still remains a challenge to create segregated structures in cross-linked polymeric networks. Herein, we report a facile methodology to construct segregated structures in sulfur-cured rubbers using an industrially accessible process toward robust, flexible, highly conductive elastomer composites. Specifically, natural rubber granules (NR-RGs) with reactive di- and polysulfides on the surface are fabricated and then mixed with NR gum, carbon nanotubes (CNTs), and curing additives, followed by compression molding to yield two-phase separate composites. In the composites, CNTs are selectively dispersed in the continuous NR phase due to the volume exclusion effect caused by the separate NR-RG phase, leading to overwhelming electrical conductivity compared to the counterparts with randomly dispersed CNTs. In addition, NR-RGs can serve as novel reinforcement for NR, imparting the composites with remarkably improved modulus and retained stretchability. The simultaneously improved electrical conductivity and mechanical properties are due to the strong interfacial adhesion between the NR matrix and NR-RGs, as the di- and polysulfides on the surface of NR-RGs can participate in the cross-linking reactions of NR gum and enable the establishment of covalent bonding across the interfaces. The universality of this approach in preparing segregated composites with a combination of high conductivities and robust mechanical properties is demonstrated using other diene rubbers as the matrix and boron nitride as the filler.

Construction of segregated structures in polymer composites is an efficient way to improve the electrical conductivity and reduce the percolation threshold by confining conductive fillers into the interstitial areas between polymer domains. Yet, it remains a great challenge to engineer segregated structures into thermosets as the cross-linked structure prohibits the "sintering" of polymer domains into a coherent material. Thus far, the state of art approaches to create segregated network in cross-linked polymers involve tedious procedures and are limited to latex mixing technology. Here, inspired by solid state plasticity of vitrimers, we present a simple method to create segregated structures in covalently cross-linked networks by compression molding of conductive filler-coated vitrimer granules. Specifically, dynamic boronic ester-cross-linked styrene-butadiene rubber vitrimers was ground into granules and then mechanically mixed with carbon nanotubes (CNTs) to coat CNTs onto vitrimer granules, followed by hot-press molding. During the molding process, the transesterifications of boronic esters enable cross-linked granules to adhere together through molecular bonding, and the high viscosity of granules forces CNTs to selectively localize at their boundary region. As a result, coherently segregated composites with an ultralow percolation threshold, good flexibility, and healing capability are obtained. With this example, we envisage that this work provides a conceptual method to create segregated structures in cross-linked polymers.

Parathyroid glands (PTGs) are important endocrine organs being mainly responsible for the secretion of parathyroid hormone (PTH) to regulate the balance of calcium (Ca) /phosphorus (P) ions in the body. Once PTGs get injured or removed, their resulting defect or loss of PTH secretion should disturb the level of Ca/P in blood, thus damaging other related organs (bone, kidney, etc.) and even causing death. Recently, tissue-engineered PTGs (TE-PTGs) have attracted lots of attention as a potential treatment for the related diseases of PTGs caused by hypoparathyroidism and hyperparathyroidism, including tetany, muscle cramp, nephrolithiasis, nephrocalcinosis, and osteoporosis. Although great progress has been made in the establishment of TE-PTGs with an effective strategy to integrate the key factors of cells and biomaterials, its regulatory secretion of PTH to mimic its natural rhythms in the body remains a huge challenge. This review comprehensively describes an overview of PTGs from physiology and pathology to cytobiology and tissue engineering. The state of the arts in TE-PTGs and the feasible strategies to regulate PTH secretion behaviors are highlighted to provide an important foundation for further investigation., (© 2020 John Wiley & Sons, Ltd.)

Successful discrimination of complex biological samples by sensor array remains a challenging problem. Herein, a three-unit fluorescence sensor array was fabricated using fluorescent molecules, which interact with proteins and generate rich response signals, to realize the discrimination of urinary proteins. As a proof of concept, six urinary proteins were selected as analytes. Results showed 100% accuracy in differentiation and quantitative discrimination of every single protein and their complex mixtures. Moreover, protein profiles of urine samples from healthy people and patients with different urinary diseases, including tubular injury (TI), diabetic nephropathy (DN), and nephropathy (Nep), were well distinguished.

Due to the exchangeability of dynamic covalent bonds in the covalent adaptable networks (CANs) at elevated temperature, they possess recyclability while still maintaining many of the superior properties of thermosets. The exploration of dynamic covalent chemistry is of great significance to the expansion of CANs library and hence the sustainable development of thermosets. In this work, we discovered that, in absence of catalyst, the direct metathesis of the cyclic acetals proceeds while the acyclic acetals cannot. The metathesis kinetics of the cyclic acetals were fully revealed with model compounds. For the CANs demonstration, a series of cross-linked spirocyclic acetal polymers with excellent reprocessability, high thermal stability, and high refractivity were prepared via thiol-ene click polymerization. We envisage that the uncovering of the catalyst-free metathesis of cyclic acetals will enrich the dynamic chemistry of acetals and greatly promote the development of acetal-based CANs and their potential applications in optical devices.

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., Competing Interests: Conflict of interest The authors declare that they have no conflict of interest., (Copyright © 2020 Science China Press. Published by Elsevier B.V. All rights reserved.)

It remains challenging to simultaneously realize mechanical robustness, malleability, and functionality in elastomers via facile yet efficient methods. Herein, a simple strategy for the biomimetic heterogeneous design is proposed to achieve mechanically strong, malleable, and functionalized elastomers. We demonstrate the strategy by straightforward mechanical mixing of a highly cross-linked vitrimeric elastomer with a homogeneous gum and subsequent curing, resulting in heterogeneous vitrimeric elastomers (hetero-VEs). The hetero-VEs comprise two phases: a hard phase with dense cross-links and a soft matrix with few cross-links, with excellent interface between the two phases. The hard phases can be deformed upon loading, dissipating energy, which significantly improves the overall mechanical performance of the hetero-VEs. When conductive fillers are incorporated into the soft matrix, due to the volume exclusion effect of the hard phases, the resultant hetero-VEs exhibit high conductivity with a small fraction of fillers. In view of the facile and generic preparation process, this strategy should be a promising way to reinforce and functionalize many vitrimeric elastomer systems.

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.

Although the incorporation of sacrificial bonds into an elastomer is an effective way to provide a combination of high strength and high fracture toughness, this method normally involves complicated chemical processes. The coordination between metal ions and polysulfides has been documented. However, the potential of polysulfide structures in vulcanizates as ligands has long been neglected. Using innate sulfur-based cross-links, we show how weak and nonpolar elastomers achieve significant reinforcement without modification of the backbone. By simply soaking vulcanizates into solutions containing metal ions, dual ions are simultaneously introduced into the vulcanizate to generate coordinations with different bond strengths, resulting in an unprecedented high modulus. Overall, this work presents a universal yet high-efficiency reinforcing strategy to prepare high-performance elastomers without additional chemical modifications, which should promote comprehensive research and industrial application of sacrificial bond strategies for elastomers.

Introduction: The aim of the study was to further explore the pathogenesis of idiopathic membranous nephropathy (IMN), gene-sequencing was used to analyze the differentially expressed circRNAs in exosomes of patients with IMN, which may lay the foundation for the research of circRNAs as a new class of exosome-based IMN diagnosis biomarkers., Material and Methods: Ten patients with IMN and ten normal controls were recruited as experimental subjects in our study. The exosomes were extracted from the collected serum and urine. Then, pure circRNAs were extracted from the exosomes with a series of enzymatic reactions. Afterwards, the significantly differentially expressed circRNAs were chosen by the method of gene-sequencing., Results: Compared with normal controls, the circRNAs were reduced in the exosomes from serum of patients with IMN, which mostly originated from intron gene regions. Meanwhile, a total of 89 circRNAs were significantly differentially expressed, which were also mostly derived from intron gene regions, including 49 up-regulated and 40 down-regulated genes. However, the species were increased in the exosomes from the urine of patients with IMN compared to normal controls, and they mainly originated from exon gene regions. Simultaneously, 60 circRNAs were significantly differentially expressed, which primarily belonged to intron gene regions, including 54 up-regulated and 6 down-regulated regions., Conclusions: The significant differential and specific expression of circRNAs in the exosomes from patients with IMN were observed. For example, MUC3A, which originated from chr7:100550808|100551062, could be considered a potential diagnostic biomarker of IMN. Furthermore, these figures may be used as a reference or supplement in the research of the pathogenesis of IMN., Competing Interests: The authors declare no conflict of interest.

Vitrimers are a class of covalently cross-linked polymers that have drawn great attention due to their fascinating properties such as malleability and reprocessability. The state of art approach to improve their mechanical properties is the addition of fillers, which, however, greatly restricts the chain mobility and impedes network topology rearrangement, thereby deteriorating the dynamic properties of vitrimer composites. Here, we demonstrate that the integration of sacrificial bonds into a vitrimeric network can remarkably enhance the overall mechanical properties while facilitating network rearrangement. Specifically, commercially available epoxidized natural rubber is covalently cross-linked with sebacic acid and simultaneously grafted with N-acetylglycine (NAg) through the chemical reaction between epoxy and carboxyl groups, generating exchangeable β-hydroxyl esters and introducing amide functionalities into the networks. The hydrogen bonds arising from amide functionalities act in a sacrificial and reversible manner, that is, preferentially break prior to the covalent framework and undergo reversible breaking and reforming to dissipate mechanical energy under external load, which leads to a rarely achieved combination of high strength, modulus, and toughness. The topology rearrangement of the cross-linked networks can be accomplished through transesterification reactions at high temperatures, which is accelerated with the increase of grafting NAg amount due to the dissociation of transient hydrogen bonds and increase of the ester concentration in the system.

Covalently cross-linked rubbers are renowned for their high elasticity that play an indispensable role in various applications including tires, seals, and medical implants. Development of self-healing and malleable rubbers is highly desirable as it allows for damage repair and reprocessability to extend the lifetime and alleviate environmental pollution. Herein, we propose a facile approach to prepare permanently cross-linked yet self-healing and recyclable diene-rubber by programming dynamic boronic ester linkages into the network. The network is synthesized through one-pot thermally initiated thiol-ene "click" reaction between a novel dithiol-containing boronic ester cross-linker and commonly used styrene-butadiene rubber without modifying the macromolecular structure. The resulted samples are covalently cross-linked and possess relatively high mechanical strength which can be readily tailored by varying boronic ester content. Owing to the transesterification of boronic ester bonds, the samples can alter network topologies, endowing the materials with self-healing ability and malleability.

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.

Rubbers are strategically important due to their indispensable applications in the daily life and high-tech fields. For their real-world applications, the covalent cross-linking, reinforcement, and malleability of rubbers are three important issues because they are closely related to the elasticity, mechanical properties, and recycling of the rubber materials. Herein, we demonstrate a simple way to prepare covalently cross-linked yet recyclable and robust elastomeric vitrimer composites by incorporating exchangeable β-hydroxyl ester bonds into the elastomer-nanoparticle interface using epoxy group-functionalized silica (Esilica) as both cross-linker and reinforcement in carboxyl group-grafted styrene-butadiene rubber (CSBR). The Esilica-cross-linked CSBR composites exhibit promising mechanical properties due to the covalent linkages in the interface and fine silica dispersion in the matrix. In addition, the interface can undergo dynamic reshuffling via transesterification reactions to alter network topology at high temperatures, conferring the resulting composites the ability to be reshaped and recycled.

Mimicking natural structures has been highly pursued in the fabrication of synthetic polymeric materials due to its potential in breaking the bottlenecks in mechanical properties and extending the applications of polymeric materials. Recently, it has been revealed that the energy dissipating mechanisms via sacrificial bonds are among the important factors which account for strong and tough attributes of natural materials. Great progress in synthesis of polymeric materials consisting of sacrificial bonds has been achieved. The present review aims at (1) summarizing progress in the mechanics and chemistry of sacrificial bond bearing polymers, (2) describing the mechanisms of sacrificial bonds in strengthening/toughening polymers based on studies by single-molecule force spectroscopy, chromophore incorporation and constitutive laws, (3) presenting synthesis methods for sacrificial bonding including dual-crosslink, dual/multiple-network, and sacrificial interfaces, (4) discussing the important advances in engineering sacrificial bonding into hydrogels, biomimetic structures and elastomers, and (5) suggesting future works on molecular simulation, viscoelasticity, construction of sacrificial interfaces and sacrificial bonds with high dissociative temperature. It is hoped that this review will provide guidance for further development of sacrificial bonding strategies in polymeric materials.

It is a significant but challenging task to simultaneously reinforce and functionalize diene rubbers. Inspired by "sacrificial bonds", the authors engineer sacrificial hydrogen bonds formed by pendent urazole groups in crosslinked solution-polymerized styrene butadiene rubber (SSBR) via triazolinedione click chemistry. This post-crosslinking modification reveals the effects of the sacrificial bonds based on a consistent covalent network. The "cage effect" of the pre-crosslinked network facilitates the heterogeneous distribution of urazole groups, leading to the formation of hydrogen-bonded multiplets. These multiplets further aggregate into clusters with vicinal trapped polymer segments that form microphase separation from the SSBR matrix with a low content of urazole groups. The clusters based on hydrogen bonds, serving as sacrificial bonds, promote energy dissipation, significantly improving the mechanical properties of the modified SSBR, and enable an additional wide transition temperature region above room temperature, which endows the modified SSBR with promising triple-shape memory behavior., (© 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Although carbon nanotubes (CNTs) have been produced in industrial scale, their poor dispersibility in organic solvents still imposes a huge challenge for their practical applications. In the present work, we propose a generic mechanochemical grafting strategy to prepare the organo-soluable CNTs, which is facile, efficient, and scalable. Significantly, the solvent spectrum of the CNTs suspension can be simply extended by changing the chemical composition of the grafted elastomer chains. The prospect of the organo-solubale CNTs is demonstrated by the free-standing buckypapers by direct filtration of the CNT colloids. Such buckypapers exhibit great potential as robust and ultraflexible conductors due to the combination of high toughness and stable conductivity under cyclic bending and twisting. Furthermore, this facile surface modification strategy of CNTs also enables remarkable improvement in mechanical properties of CNT-based rubber composites. We envision that the present work offers a facile yet efficient strategy for scalable production of organosoluable CNTs and other nanoparticles, which is of great scientific and technological interest.

It poses a huge challenge to expand the application gallery of rubbers into advanced smart materials and achieve the reinforcement simultaneously. In the present work, inspired by the metal-ligand complexations of mussel byssus, ferric ion was introduced into an oxygen-abundant rubber network to create additional metal-oxygen coordination cross-links. Such complexation has been revealed to be highly efficient in enhancing the strength and toughness of the rubbers. Significantly, such complexation also enables the functionalization of the rubber into highly damping or excellent multishape memory materials. We envision that the present work offers an efficient yet facile way of creating advanced elastomers based on industrially available diene-based rubber.

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., (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

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.

It remains a huge challenge to create advanced elastomers combining high strength and great toughness. Despite enhanced strength and stiffness, elastomeric nanocomposites suffer notably reduced extensibility and toughness. Here, inspired by the concept of sacrificial bonding associated with many natural materials, a novel interface strategy is proposed to fabricate elastomer/graphene nanocomposites by constructing a strong yet sacrificial interface. This interface is composed of pyridine-Zn(2+) -catechol coordination motifs, which is strong enough to ensure uniform graphene dispersion and efficient stress transfer from matrix to fillers. Moreover, they are sacrificial under external stress, which dissipates much energy and facilitates chain orientation. As a result, the strength, modulus, and toughness of the elastomeric composites are simultaneously strikingly enhanced relative to elastomeric bulk. This work suggests a promising methodology of designing advanced elastomers with exceptional mechanical properties by engineering sacrificial bonds into the interface., (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Resolving the structure of natural rubber (NR) has been an important issue for a long time and essential progress has been made. It is well established that non-rubber components have significant effects on the performance of NR. A detailed discussion on the effects of proteins and phospholipids on the chain dynamics of NR will be crucial for the in-depth understanding of the role of proteins and phospholipids in NR. However, to date, there is still a lack of elaborate studies on the dielectric spectroscopy of NR. In the present study, we performed detailed dielectric relaxation analysis, together with rheological measurements, to reveal the effects of proteins and phospholipids on the chain dynamics of NR. Distinctly different from the widely accepted segmental mode (SM) and normal mode (NM), a new relaxation mode in deproteinized NR (DPNR) was identified for the first time, which cannot be found either in NR or in transesterified DPNR (TE-DPNR). Because this new mode relaxation process behaves as a thermally activated process and it is about four orders of magnitude slower than NM, it could be rationally attributed to the relaxation of the phospholipids core of DPNR, named branch mode (BM) relaxation. When further conversion of DPNR to TE-DPNR was conducted, the phospholipids were removed and BM disappeared. In addition, a new relaxation mode, which occurs at considerably lower temperature than that for SM, was revealed in TE-DPNR, and may be related to the relaxation of free mono- or di-phosphate groups at the α ends in TE-DPNR. Hence, the identification of the new relaxation modes in DPNR and TE-DPNR provide new evidence for the natural networking structure linked by protein-based ω ends and phospholipids-based α ends.

Two-dimensional MoS2 nanoplates within carbon nanofibers (CNFs) with monolayer thickness, nanometer-scale dimensions and abundant edges are fabricated. This strategy provides a well-defined pathway for the precise design of MoS2 nanomaterials, offering control over the evolution of MoS2 morphology from nanoparticles to nanoplates as well as from mono- to several-layer structures, over a lateral dimension range of 5 to 70 nm. CNFs play an important role in confining the growth of MoS2 nanoplates, leading to increases in the amount of exposed edge sites while hindering the stacking and aggregation of MoS2 layers, and accelerating electron transfer. The controlled growth of MoS2 nanoplates embedded in CNFs is leveraged to demonstrate structure-dependent catalytic activity in the hydrogen evolution reaction (HER). The results suggest that increases in the number of layers and the lateral dimension result in a decrease in HER activity as a general rule. Single-layer MoS2 nanoplates with abundant edges and a lateral dimension of 7.3 nm demonstrated the lowest hydrogen evolution reaction overpotential of 93 mV (J = 10 mA/cm(2)), the highest current density of 80.3 mA/cm(2) at η = 300 mV and the smallest Tafel slope of 42 mV/decade. The ability of MoS2-CNFs hybrids to act as nonprecious metal catalysts indicates their promise for use in energy-related electrocatalytic applications.

S-rich MoS2-NCNF hybrid nanomaterials exhibiting extraordinary HER activity, with a very low onset potential of 30 mV and a small Tafel slope of 38 mV per decade, were successfully fabricated by combining N-doped carbon nanofibers and single-layered MoS2 nanostructures with abundant edge active sites.

Reversible plasticity shape memory (RPSM) is a new concept in the study of shape memory performance behavior and describes a phenomenon in which shape memory polymers (SMPs) can undergo a large plastic deformation at room temperature and subsequently recover their original shape upon heating. To date, RPSM behavior has been demonstrated in only a few polymers. In the present study, we implement a new design strategy, in which deformable glassy hindered phenol (AO-80) aggregates are incorporated into an amorphous network of epoxidized natural rubber (ENR) cured with zinc diacrylate (ZDA), in order to achieve RPSM properties. We propose that AO-80 continuously tunes the glass transition temperature (Tg) and improves the chain mobility of the SMP, providing traction and anchoring the ENR chains by intermolecular hydrogen bonding interactions. The RPSM behavior of the amorphous SMPs is characterized, and the results demonstrate good fixity at large deformations (up to 300%) and excellent recovery upon heating. Large energy storage capacities at Td in these RPSM materials are demonstrated compared with those achieved at elevated temperature in traditional SMPs. Interestingly, the further revealed self-healing properties of these materials are closely related to their RPSM behavior.

Novel biobased isosorbide-containing copolyesters (PBISI copolyesters) with both biocompatibility and sustainability were synthesized by using commercially available biobased diols and diacids. Due to the presence of itaconate in copolyesters, it can be readily crosslinked by peroxide into a crystallizable network. The structure and thermal properties of PBISI copolyesters were determined by 1 H NMR, FTIR, DSC, and WAXD. The chain composition, melting point and crystallinity of the PBISI copolyesters can be tuned continuously by changing the content of isosorbide. The crosslinked copolyester is demonstrated to be a promising shape memory polymer (SMP) with excellent shape memory properties including shape fixity and shape recovery rate close to 100%. The switching temperatures of PBISI-based SMPs can be tuned between 26 °C and 54 °C by altering the composition of PBISI copolyesters and curing extent. Cell adhesion and proliferation were adopted to evaluate the potential biocompatibility of PBISI-based SMPs, and the results indicated that all the PBISI-based SMPs were essentially noncytotoxic, making them suitable for fabricating biomedical devices.

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.

A simple solvent exchange method is presented to suspend monolayers of MoS2 in various organic solvents, which facilitates the phase transformation of MoS2 and preparation of MoS2-filled polymer composites straightforwardly in organic solvents.

The research advances in rubber/halloysite nanotubes (rubber/HNTs) nanocomposites are reviewed. HNTs are environmentally-friendly natural nanomaterials, which could be used to prepare the rubber-based nanocomposites with high performance and low cost. Unmodified HNTs could be adopted to prepare the rubber/HNTs composites with improved mechanical properties, however, the rubber/HNTs nanocomposites with fine morphology and excellent properties were chiefly prepared with various modifiers by in situ mixing method. A series of rubber/HNTs nanocomposites containing several rubbers (SBR, NR, xSBR, NBR, PU) and different modifiers (ENR, RH, Si69, SA, MAA, ILs) have been investigated. The results showed that all the rubber/HNTs nanocomposites achieved strong interfacial interaction via interfacial covalent bonds, hydrogen bonds or multiple interactions, realized significantly improved dispersion of HNTs at nanoscale and exhibited excellent mechanical performances and other properties.

State-of-the-art processes cannot achieve rubber/multi-walled carbon nanotube (MWCNT) composites with satisfactory performance by using pristine MWCNTs and conventional processing equipment. In this work, high performance rubber/MWCNT composites featuring a combination of good mechanical properties, electrical and thermal conductivities and damping capacity over a wide temperature range are fabricated based on a well-developed master batch process. It is demonstrated that the MWCNTs are dispersed homogeneously due to the disentanglement induced by well-wetting and shearing, and the elastic-resilience-induced dispersion of the MWCNTs by rubber chains via the novel processing method. To further enhance the efficacy of elastic-resilience-induced dispersion for MWCNTs, a slightly pre-crosslinked network is constructed in the master batch. Consequently, we obtain rubber/MWCNT composites with unprecedented performance by amplifying the reinforcing effect of relatively low MWCNT loading. This work provides a novel insight into the fabrication of high performance functional elastomeric composites with pristine CNTs by taking advantage of the unique elastic resilience of rubber chains as the driving force for the disentanglement of CNTs.

The functionalized graphene (JTPG) is fabricated by chemical conversion of graphene oxide (GO), using tea polyphenols (TP) as the reducer and stabilizer, followed by further derivatization through the Mannich reaction between the pyrogallol groups on TP and Jeffamine M-2070. JTPG exhibits solubility in a broad spectrum of solvents, long-term stability and single-layered dispersion in water and organic solvents, which are substantiated by AFM, TEM, and XRD. The paper-like JTPG hybrids prepared by vacuum-assisted filtration exhibits an unusual combination of high toughness (tensile strength of ~275 MPa and break strain of ~8%) and high electrical conductivity (~700 S/m). Still, JTPG is revealed to be very promising in the fabrication of polymer/graphene composites due to the excellent solubility in the solvent with low boiling point and low toxicity. Accordingly, as an example, nitrile rubber/JTPG composites are fabricated by the solution compounding in acetone. The resulted composite shows low threshold percolation at 0.23 vol.% of graphene. The versatilities both in dispersibility and performance, together with the scalable process of JTPG, enable a new way to scale up the fabrication of the graphene-based polymer composites or hybrids with high performance.

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.

For the purpose of preparing liquefied graphene oxide (GO), a process consisting of sulfonation with sodium sulfanilic acid and ionization with bulky amine-terminated Jeffamine® was designed and performed. The obtained hybrid fluid is actually a supramolecular ionic liquid (SIL) with sulfonated GO as the central anions and the terminal ammonium groups of Jeffamine® as the surrounding cations. The successful grafting of the GO sheets with Jeffamine®via an ionic structure was verified and the morphology of the SIL was characterized. The SIL based on GO (GO-SIL) exhibits excellent solubility and amphiphilicity. The rheological measurements confirm the essential viscoelasticity and the liquid-like behavior of GO-SIL. The present GO based SIL suggests promising applications in the fabrication of various GO or graphene based composite materials. In addition, the new functionalization method may guide the future work on acquiring derivatives with tunable properties by simply changing the bulky canopy.

The reinforcement effects of halloysite nanotubes on styrene-butadiene rubber and the modification effect of epoxidized natural rubber on styrene-butadiene rubber/halloysite nanotubes composites were studied. The structure, morphology and properties of styrene-butadiene rubber/halloysite nanotubes composites before and after the incorporation of epoxidized natural rubber were investigated. The results indicated that epoxidized natural rubber can promote the dispersion and orientation of halloysite nanotubes in styrene-butadiene rubber matrix at nanoscale and strengthen interfacial combination between halloysite nanotubes and styrene-butadiene rubber by the formation of covalent bonds and hydrogen bonds between epoxidized natural rubber and halloysite nanotubes. Consequently epoxidized natural rubber can improve the mechanical properties of the vulcanizates of styrene-butadiene rubber/halloysite nanotubes composites. Besides epoxidized natural rubber can decrease the rolling resistance of the vulcanizates and increase the wet grip property of the vulcanizates.

High mechanical performance nitrile-butadiene rubber (NBR) with light color was fabricated by the method of in situ formation of zinc disorbate (ZDS) or magnesium disorbate (MDS). The in situ formed ZDS and its polymerization via internal mixing was confirmed by X-ray diffaraction. The mechanical properties, ageing resistance, morphology and the dynamic mechanical analysis were fully studied. It was found that with increasing loading of metallic disorbate both the curing rate and the ionic crosslink density was largely increased. The modulus, tensile strength and tear strength were largely increased. With a comparison between internal mixing and opening mixing, the mechanical performance for the former one was obviously better than the latter one. The high performance was ascribed to the finely dispersion nano domains with irregular shape and obscure interfacial structures. Except for the NBR vulcanizate with a high loading of MDS, the others' ageing resistance with incorporation of these two metallic disorbate was found to be good. Dynamic mechanical analysis (DMA) showed that, with increasing loading of metallic disorbate, the highly increased storage modulus above -20 degrees C, the up-shifted glass transition temperature (Tg) and the reduced mechanical loss were ascribed to strengthened interfacial interactions.

From the point of better biocompatibility and sustainability, biobased shape memory polymers (SMPs) are highly desired. We used 1,3-propanediol, sebacic acid, and itaconic acid, which have been industrially produced via fermentation or extraction with large quantities as the main raw materials for the synthesis of biobased poly(propylene sebacate). Diethylene glycol was used to tailor the flexibility of the polyester. The resulted polyesters were found to be promising SMPs with excellent shape recovery and fixity (near 100% and independent of thermomechanical cycles). The switching temperature and recovery speed of the SMPs are tunable by controlling the composition of the polyesters and their curing extent. The continuously changed switching temperature ranging from 12 to 54 °C was realized. Such temperature range is typical for biomedical applications in the human body. The molecular and crystalline structures were explored to correlate to the shape memory behavior. The combination of potential biocompatibility and biodegradability of the biobased SMPs makes them suitable for fabricating biomedical devices.

In this contribution, halloysite nanotubes (HNTs), a kind of natural hydrophilic nanoclay, are incorporated into polypropylene (PP) for tailoring the surface microstructures of the composites prepared by solution casting. HNTs act as heterogeneous nuclei for PP, which leads to the change of phase separation process during drying of the composites and consequently the microstructures of composite surfaces. Micro-papilla like hybrid spherulites with nanostructures are formed on the PP/HNTs composite surfaces. The rough surfaces demonstrate superhydrophobicity with a maximum water contact angle as nearly 170 degrees and sliding angle of about 2 degrees. The spherulites size, surface roughness, and wetting property of PP can be tuned by HNTs. HNTs can significantly improve the thermal degradation behavior of the composites which is attributed to the well-dispersed HNTs and the improved interfacial interactions by the nucleation effect. The present work provides an alternative routine for preparing polymer superhydrophobic surfaces via tailoring the surface microstructures by adding nanoparticles in a solution process., (Copyright 2010 Elsevier Inc. All rights reserved.)

In this study, transparent poly(vinyl alcohol) (PVA) and PVA/halloysite nanotubes (HNTs) bionanocomposite films were prepared by solution casting and glutaraldehyde (GA) crosslinking. The surface topography and chemistry of the films were characterized by atomic force microscopy (AFM) and attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy, respectively. Blending with HNTs induced changes in nanotopography and surface chemistry of PVA films. The mechanical properties of PVA were enhanced by the incorporated HNTs. The stain-induced crystallization was confirmed by DSC after tensile test. MC3T3-E1 osteoblast-like and NIH 3T3 fibroblast cells were cultured on neat PVA and PVA/HNTs films to evaluate the effects of surface nanotopography and composition on cell behavior. The observations indicated that MC3T3-E1 cell behavior strongly responded to surface nanotopography. On nanotube-dominant surface, cells exhibited a significantly higher level of adhesion than on neat PVA film, whereas neat PVA showed higher degree of osteoblast proliferation compared with PVA/HNTs. In vitro fibroblasts response demonstrated that both neat PVA and PVA/HNTs nanocomposite films were biocompatible and PVA/HNTs films favored to fibroblasts attach and growth below 7.5 wt % of HNTs incorporated. In summary, these results provided insights into understanding of PVA and PVA/HNTs bionanocomposite films in potential applications in bone tissue engineering and drug delivery systems., ((c) 2009 Wiley Periodicals, Inc.)

Many types of clay tend to absorb organics via electron transferring interactions between the clay and the organics. This may be utilized to design clay incorporated polymer composites with better interfacial properties. In the present paper, 2,5-bis(2-benzoxazolyl) thiophene (BBT), capable of donating electrons, is selected as the interfacial modifier for polypropylene (PP)/halloysite nanotube (HNTs) composites. The electron transfer between HNTs and BBT are confirmed. The mechanical properties and the unique morphology of the nanocomposites are examined. Formation of fibrils of BBT in the presence of HNTs is found in the nanocomposites. The chemical composition of the fibrils in the nanocomposites is found to be composed of largely BBT and a small amount of HNTs. The formation mechanism of BBT fibrils are elucidated to be the strong interactions between BBT and HNTs under melt shearing. The formation of the BBT fibrils leads to much higher crystallinity compared with previously reported PP nanocomposites. The nanocomposites with BBT show substantially increased tensile and flexural properties, which are attributed to the enhanced crystallinity of the nanocomposites.