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1.
Arch Med Sci ; 15(3): 738-753, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-31110542

RESUMO

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.

2.
ACS Appl Mater Interfaces ; 10(28): 23485-23489, 2018 Jul 18.
Artigo em Inglês | MEDLINE | ID: mdl-29975499

RESUMO

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.

3.
ACS Appl Mater Interfaces ; 10(28): 24224-24231, 2018 Jul 18.
Artigo em Inglês | MEDLINE | ID: mdl-29943978

RESUMO

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.

4.
ACS Appl Mater Interfaces ; 10(3): 2992-3001, 2018 Jan 24.
Artigo em Inglês | MEDLINE | ID: mdl-29280383

RESUMO

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 ß-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.

5.
Chem Soc Rev ; 46(20): 6301-6329, 2017 Oct 16.
Artigo em Inglês | MEDLINE | ID: mdl-28868549

RESUMO

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.

6.
ACS Appl Mater Interfaces ; 9(8): 7666-7674, 2017 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-28168871

RESUMO

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.

7.
Macromol Rapid Commun ; 38(7)2017 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-28199759

RESUMO

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.


Assuntos
Butadienos/química , Butadienos/síntese química , Química Click , Elastômeros/química , Elastômeros/síntese química , Estirenos/química , Estirenos/síntese química , Triazóis/química , Biomimética , Ligação de Hidrogênio
8.
ACS Appl Mater Interfaces ; 8(47): 32520-32527, 2016 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-27933856

RESUMO

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.

9.
Macromol Rapid Commun ; 37(19): 1603-1610, 2016 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-27483452

RESUMO

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.


Assuntos
Ácido Cítrico/química , Ácidos Decanoicos/química , Ácidos Dicarboxílicos/química , Elastômeros/química , Elastômeros/síntese química , Tecnologia Biomédica , Ligação de Hidrogênio , Substâncias Macromoleculares/síntese química , Substâncias Macromoleculares/química , Substâncias Macromoleculares/farmacologia , Teste de Materiais , Estrutura Molecular , Tamanho da Partícula , Propriedades de Superfície , Temperatura
10.
Soft Matter ; 12(33): 6893-901, 2016 Aug 17.
Artigo em Inglês | MEDLINE | ID: mdl-27387393

RESUMO

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.

11.
Macromol Rapid Commun ; 37(13): 1040-5, 2016 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-27229634

RESUMO

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.


Assuntos
Catecóis/química , Elastômeros/química , Grafite/química , Nanocompostos/química , Piridinas/química , Zinco/química , Ligantes , Estrutura Molecular
12.
Soft Matter ; 11(11): 2290-9, 2015 Mar 21.
Artigo em Inglês | MEDLINE | ID: mdl-25656324

RESUMO

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.


Assuntos
Espectroscopia Dielétrica/métodos , Borracha/química , Módulo de Elasticidade , Modelos Moleculares , Proteínas/isolamento & purificação , Temperatura
13.
ACS Appl Mater Interfaces ; 6(24): 22126-37, 2014 Dec 24.
Artigo em Inglês | MEDLINE | ID: mdl-25420219

RESUMO

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.

14.
ACS Appl Mater Interfaces ; 6(23): 21060-8, 2014 Dec 10.
Artigo em Inglês | MEDLINE | ID: mdl-25389952

RESUMO

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.

15.
Chem Commun (Camb) ; 50(97): 15435-8, 2014 Dec 18.
Artigo em Inglês | MEDLINE | ID: mdl-25351793

RESUMO

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.

16.
J Nanosci Nanotechnol ; 14(2): 1758-71, 2014 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-24749454

RESUMO

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.


Assuntos
Silicatos de Alumínio/química , Cristalização/métodos , Nanotubos/química , Nanotubos/ultraestrutura , Borracha/química , Argila , Módulo de Elasticidade , Dureza , Substâncias Macromoleculares/química , Teste de Materiais , Conformação Molecular , Tamanho da Partícula , Propriedades de Superfície
17.
ACS Appl Mater Interfaces ; 6(8): 5695-703, 2014 Apr 23.
Artigo em Inglês | MEDLINE | ID: mdl-24673791

RESUMO

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.

18.
Chem Commun (Camb) ; 50(30): 3934-7, 2014 Apr 18.
Artigo em Inglês | MEDLINE | ID: mdl-24595701

RESUMO

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.

19.
Nanotechnology ; 24(46): 465708, 2013 Nov 22.
Artigo em Inglês | MEDLINE | ID: mdl-24164916

RESUMO

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.

20.
ACS Appl Mater Interfaces ; 5(6): 2174-81, 2013 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-23465413

RESUMO

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.

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