INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
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2024
·
IF 8.1
Xiuquan Li,Ziqiang He,Congbo Li,Dugang Kang,Jie Chen,Youhong Wang,Fei Wang,Song Huang,Zhien Zhang
Aiming at the resource utilization of CO 2 and the value-added catalytic conversion of ethane, different reducibility oxide carriers were used to study. Through catalytic reaction experiments, catalyst characterization and kinetic analysis , the interaction between reducible carriers and active metals and their regulation on the catalytic reaction performance of ethane with CO 2 were revealed. Fe 1.5 Ni 0.5 /CeO 2 has the highest ethylene selectivity of 87% near 650 °C, and is a good catalyst for the CO 2 -assisted ethane oxidative dehydrogenation to ethylene reaction. The strong interaction between the reducible CeO 2 and ZrO 2 carriers and active metals makes the Fe–O–Ce and Fe–O–Zr covalent bonds on the Fe 1.5 Ni 0.5 /CeO 2 and Fe 1.5 Ni 0.5 /ZrO 2 catalysts stronger than Fe–O–Ti and Fe–O–Al covalent bonds on Fe 1.5 Ni 0.5 /TiO 2 and Fe 1.5 Ni 0.5 /γ-Al 2 O 3 catalysts. The lattice oxygen on the reducible catalyst is more readily involved in the reaction. The strong interaction between the active metal and the carrier results in the reduction of the FeO x species and the formation of new active sites, resulting in a high reactivity of the catalyst. The mutually promoted redox cycle between the active species Fe 3+/2+ -Ni 2+/0 and the reducible carrier variable metal Ce 4+/3+ species improves the catalytic performance for the reaction of ethane awith CO 2 .
研究领域:
化学工程
·
催化科学
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高影响因子
Extreme Mechanics Letters
·
2024
·
IF 4.3
Xi Chen,Jiayi Lin,Hang Yang,Jingda Tang
Dynamic covalent bonds endow polymers with unique mechanical properties, such as tunable viscoelastic response and self-healing capability. The study on the fracture of dynamic polymers has recently initiated. However, it is still elusive how dynamic covalent bonds affect the flaw sensitivity of dynamic polymers. Here, we prepare the polyacrylamide hydrogel with dynamic disulfide bonds as the model material. Under UV irradiation, dynamic bond exchange reaction effectively releases the stress concentrated at the crack tip, making the hydrogel less flaw sensitive. Notably, both the rupture stretch and rupture stress of dynamic hydrogels under UV irradiation are much higher than the control group. We further investigate the effect of photoinitiator concentration and dynamic bond content on the flaw sensitivity of dynamic hydrogels. The increase of photoinitiator concentration or dynamic bond content intensifies the dynamic bond exchange reaction, causing more stress relaxation and improved flaw insensitivity of the hydrogel. Moreover, we exploit this flaw insensitivity to tune the crack propagation path in dynamic hydrogel with double edge cracks. The crack propagates in the non-irradiated area, but is retarded in the irradiated area to show asymmetric fracture mode. We hope this work can provide new insights for the design of polymers with dynamic covalent bonds.
研究领域:
材料科学
·
高分子化学
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Nature Communications
·
2024
·Vol. 15
·期 1
·1-12
·
IF 14.7
Li Xiaopei,Zhang Yongjie,Shi Zhenqiang,Wang Dongdong,Yang Hang,Zhang Yahui,Qin Haijuan,Lu Wenqi,Chen Junjun,Li Yan,Qing Guangyan
Boroxines are significant structures in the production of covalent organic frameworks, anion receptors, self-healing materials, and others. However, their utilization in aqueous media is a formidable task due to hydrolytic instability. Here we report a water-stable boroxine structure discovered from 2-hydroxyphenylboronic acid. We find that, under ambient environments, 2-hydroxyphenylboronic acid undergoes spontaneous dehydration to form a dimer with dynamic covalent bonds and aggregation-induced enhanced emission activity. Intriguingly, upon exposure to water, the dimer rapidly transforms into a boroxine structure with excellent pH stability and water-compatible dynamic covalent bonds. Building upon these discoveries, we report the strong binding capacity of boroxines toward fluoride ions in aqueous media, and develop a boroxine-based hydrogel with high acid–base stability and reversible gel–sol transition. This discovery of the water-stable boroxine structure breaks the constraint of boroxines not being applicable in aqueous environments, opening a new era of researches in boroxine chemistry.
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PubMed
高影响因子
Extreme Mechanics Letters
·
2022
·
IF 4.728
Yihang Xiao,Qi Li,Xi Yao,Ruobing Bai,Wei Hong,Canhui Yang
Hydrogels composed of amorphous polymer networks are widely used as soft and stretchable components in diverse devices and machines. However, existing amorphous hydrogels are susceptible to fatigue fracture. Here, we propose that amorphous hydrogels with dynamic covalent bonds can resist fatigue fracture, so long as the dynamics of bond recovery is faster than the rate of deformation. We examine this hypothesis by performing fatigue tests for polyacrylamide hydrogels crosslinked by covalent C–C bonds and by dynamic covalent siloxane bonds, using N, N’-methylenebis-acrylamide (MBAA) and silanes as the crosslinkers , respectively. Experiments show that the fatigue threshold of MBAA-crosslinked hydrogels is 12.7 J/m 2 , much lower than the toughness, 70.2 J/m 2 , and comparable to the Lake–Thomas prediction, 11.17 J/m 2 , while the silane-crosslinked hydrogels achieve a fatigue threshold of 68.7 J/m 2 , surprisingly close to the toughness, 86.2 J/m 2 , which is reported for the first time in hydrogels with dynamic covalent bonds. We trace the violation of the Lake–Thomas mechanism to the dynamic nature of siloxane bonds. We carry out self-healing tests, self-recovery tests, and fatigue tests for silane-crosslinked hydrogels with different pH values to examine the bond dynamics. We discuss the importance of dynamic covalent bonds in synthesizing fatigue-free hydrogels by constructing a fatigue threshold-toughness Ashby plot. The current work suggests that dynamic covalent bonds pave alternative avenues towards anti-fatigue soft materials with amorphous polymer networks.
研究领域:
材料科学
·
生物工程
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高影响因子
Journal of Materials Chemistry B
·
2015
·Vol. 4
·期 4
·694-703
·
IF 4.726
Jie Deng,Xinyue Liu,Lang Ma,Chong Cheng,Shudong Sun,Changsheng Zhao
The development of biointerfaces with switchable properties is of growing interest for fabricating advanced biomaterials since the adjustment of surface properties can be made on demand. Herein, we report a highly versatile approach for the preparation of a switchable biointerface through a dynamic covalent bond (DCB). The switchability can be achieved via the reversible attaching/detaching of aldehyde end-functionalized biomacromolecules onto/from an acylhydrazide anchored substrate surface. By applying the DCB protocol, three types of well-designed aldehyde end-functionalized biomacromolecules including aldehyde-poly(styrenesulfonate)-co-poly(ethylene glycol)methyl ether methacrylate (Ald-PSP, blood compatible), aldehyde-poly([2-(meth acryloyloxy)ethyl]trimethylammonium chloride) (Ald-PMT, antibacterial), and aldehyde-poly([2-(meth acryloyloxy)ethyl]trimethylammonium chloride-co-poly(ethylene glycol)methyl ether methacrylate) (Ald-PMP, combined antifouling and antibacterial) could be reversibly and alterably immobilized on the substrate surface by switching the pH conditions. As a result, we succeeded in altering the biointerface performances; excellent blood compatibility, antibacterial ability, or combined antifouling and antibacterial capabilities could be alterably achieved on the biointerface, which made the obtained material interfaces more adaptable and capable of satisfying different biofunctional requirements. Moreover, many other properties with specific biofunctions of interests can also be achieved via designing specific aldehyde-terminated molecules.
研究领域:
材料科学
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生物材料
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生物技术
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PubMed
高影响因子
JOURNAL OF POLYMER SCIENCE
·
2023
·
IF 3.4
Yanna Zhao,Yuqing Huang,Wentong Hou,Ting Zhang,Yingying Zhang,Yuqi Wang,Xiaowei Bai
Vitrimer films containing acylhydrazone bonds are synthesized in two steps. Bio-based vanillin and adipate dihydrazide are used to prepare diols containing acylhydrazone bonds in one step, which are introduced into the reaction system of vitrimer to obtain the final films. The process is concise and easy to operate. By utilizing the rigid structure of vitrimer films and introducing dynamic acylhydrazone bonds, the obtained vitrimer films exhibit strong mechanical strength (maximum tensile strength of 27.10 MPa and maintaining up to 185.52% of the original breaking strength), excellent self-healing property (tensile strength of 26.26 MPa after 12 h of primary self-healing and 5.24 MPa after 12 h of secondary self-healing), and rapid shape memory property (recovery time of about 2 min), strong acid and alkali resistance (not dissolved within 24 h), good thermal stability (no decomposition occurs below 160 °C), and high storage modulus (reaches 1087 MPa). These comprehensive benefits yield a certain reference for the preparation of vitrimer materials with prime properties. Graphical
研究领域:
材料科学
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化学工程
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高影响因子
EUROPEAN POLYMER JOURNAL
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2026
·
IF 6.8
Jiajie Zhou,Fengxiang Cao,Mingwu Yu,Zhen Fang,Zhuhui Qiao
Tunable mechanical properties from rigid to soft via monomer selection. • Excellent thermally-induced healing, reprocessing, and partial recovery to vanillin. • High adhesion performance: 9 MPa lap shear strength on steel substrates. • Bio-based vitrimers with multiple dynamic covalent bonds for sustainability. Replacing petrochemical-derived bisphenol A (BPA) in high-performance thermosets remains a critical challenge. Herein, we report the facile synthesis of a vanillin-derived multifunctional intermediate (BA) to construct dynamically cross-linked epoxy vitrimers. By curing BA with 4,4-diaminodiphenylmethane (DDM) alongside distinct epoxy monomers-either diglycidyl ether of bisphenol A (DGEBA) or epoxidized soybean oil (ESO)-we engineered materials with highly tunable properties. Remarkably, tailoring the epoxy monomer enables a transition from rigid to flexible networks; the fully bio-based BA/ESO system can be modulated from soft to hard simply by adjusting the ESO content. The rigid BA/DGEBA network outperforms commercial DGEBA/DDM, exhibiting a 29.4 % enhanced storage modulus (3066 MPa), a 23.0 % increased tensile strength (89.7 MPa), and a 2.85-fold increase in char yield (33.26 %). Furthermore, multiple dynamic covalent bonds endow these vitrimers with exceptional remodeling, thermally-induced healing, and adhesive capabilities (9 MPa lap shear strength on steel). Crucially, the vitrimers are capable of degrading completely within 1 h under alkaline conditions at 80 °C to recover the starting vanillin with a recovery rate up to 43.6 %. This strategy presents a robust, tunable alternative to BPA-based resins, advancing green polymer development. Download: Download high-res image (148KB) Download: Download full-size image
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MACROMOLECULES
·
2023
·
IF 5.5
Huagao Fang,Fan Zhang,Yongpu Zhao,Xingchen Gao,Wenjuan Zhou,Guobin Qi,Yunsheng Ding,H. Henning Winter
Liquid crystal elastomer networks (LCEs) have found a wide range of applications due to their unusual mechanical and optical properties. The introduction of dynamic covalent bonds with their possibilities for network renewal opens up further opportunities. Elastomeric vitrimer epoxies (EV, m-EV, and vLCE) were synthesized with increased liquid crystal mesogens (LCM), in which the rheological properties vary with the fraction of LCM in the backbone. Differing from EV and m-EV, the distinctive contributions arising from the smectic structure in the vLCE were manifested in several viscoelastic responses. The underlying mechanisms were discussed for the first time. The smectic-isotropic transition of LCM is expressed, and the residual partially ordered structure in vLCEs contributes to the relatively high storage modulus in heating scans and seems to be the cause of thermal memory effects in the closed-loop cooling and heating experiment. Time–temperature superposition (tTS) is applicable to the EV and m-EV. vLCE becomes─thermorheologically complex in the vicinity of the order–disorder transition temperature of LCM domains. The temperature dependence of the shift factors in tTS can be divided into two regions, showing Williams–Landel–Ferry (WLF)-type at lower temperatures and Arrhenius-type at higher temperatures. At lower temperatures, the flow activation energy (EWLF) increases in the sequence of EV, m-EV, and vLCE, reflecting the increase in backbone stiffness and its control over chain mobility. The activation energy, associated with the release of the transient cross-link from a smectic layer, also exists in vLCE. Above the LC transition temperature, a stretched exponential Kohlrausch–Williams–Watts (KWW) function is introduced to quantitatively describe the network rearrangement kinetics in the stress relaxation process; a low exponent β indicates marked structural heterogeneity in vLCE. Increased LCM causes stress relaxation processes to slow down significantly in a highly elastic state. The activation energy (Ea) obtained from the Arrhenius dependence of characteristic relaxation times declines as the LCM content is increased. This could be attributed to the locally higher concentration of the ester group and catalyst in vLCE.
研究领域:
材料科学
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物理学
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高影响因子
JOURNAL OF APPLIED POLYMER SCIENCE
·
2024
·Vol. 141
·期 48
·e56281
·
IF 2.7
Yanna Zhao,Yingying Zhang,Xiaowei Bai,Yuqi Wang,Yiqing Li,Shuai Yang
Polyimide materials with high mechanical strength are widely used in various fields, but pose certain challenges in achieving sustainable material utilization. A poly(imide-imide) vitrimer material (ADTA) based on multiple dynamic covalent bonds (imide, imine, and disulfide bonds) was constructed by preparing vanillin difunctionalized derivatives (DVA) for aldolamine condensation reactions with bis-amine monomers (ATFA) and tris(2-aminoethyl) amines (TAEA) with imide structures. The ADTA material has good 5% thermal stability T d 5% (278.87°C), high energy storage modulus E (2421.26 MPa), and fast relaxation time (36.39 s). The thermal stability and mechanical properties of the material are enhanced by the more stable alicyclic structure of the imide structure. The material also demonstrated excellent solvent resistance and self-healing properties. This study provides a new option for the development of sustainable utilization of polyimide materials.
研究领域:
材料科学
·
化学工程
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高影响因子
Soft Matter
·
2015
·Vol. 11
·期 27
·5546-5553
·
IF 4.029
Na Xu,Jie Han,Zhengguang Zhu,Bo Song,Xinhua Lu,Yuanli Cai
An emerging strategy towards the sophistication of supramolecular nanomaterials is the use of supracolloidal self-assembly, in which micelles or colloids are used as building blocks. Binding directionality can produce nanostructures with attractive properties. Herein, we present a new directional supracolloidal self-assembly by virtue of dynamic covalent bonds and metal coordination in water. Conjugation of a ligand precursor to a water-soluble block copolymer through dynamic covalent bonds leads to the dehydration and micellization of the functionalized polymer. Reversible reaction facilitates the permeation of metal ions into core–shell interfaces. Conversely, metal-coordination promotes reaction over the interfaces. Cu(II)-coordination occurs overwhelmingly inside each isolated micelle. However, Zn(II)-coordination induced a directional self-assembly whose nanostructures evolve stepwise from nanorods, nanowires, necklaces, and finally to supracolloidal networks scaling-up to several tens of micrometres. Post-reactions of simultaneous dynamic covalent bond conversion and Zn(II)-coordination over the core–shell interfaces endow these supracolloidal networks with a huge specific surface area for hydrophobic dative metal centres accessible to substrates in water. Water-soluble shells play important roles in directional supracolloidal assembly and in the stabilization of nanostructures. Thus the directional self-assembly provides a versatile platform to produce metallo-hybridized nanomaterials that are promising as enzyme-inspired aqueous catalysts.
研究领域:
材料科学
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纳米技术
·
化学
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PubMed
高影响因子
Coatings
·
2026
·Vol. 16
·期 4
·404
·
IF 3.4
Maorong Li,Zhaoyi He,Mengkai Sun,Le Yu,Lin Kong
HighlightsWhat are the main findings?Optimal R-value elevation enhances SSDA-PU’s mechanical properties.The disulfide bonds indirectly contribute to the reinforcement and toughening of the DA-PU system.What are the implications of the main findings?The polyurethane with dual dynamic covalent bonds enables multiple self-healing of the elastomer.SSDA-PU’s self-healing stems from synergistic multi-bond effects.Dynamic covalent bonds are commonly used to maintain the self-healing properties of polyurethanes and facilitate resource recycling. However, relying on a single type of dynamic covalent bond often makes it difficult to effectively regulate both mechanical and self-healing properties across a wide temperature range. In this study, a self-synthesized chain extender containing disulfide bonds was introduced into a polyurethane system, leading to the development of a novel dual-dynamic covalent bond self-healing polyurethane (SSDA-PU). Innovatively, this SSDA-PU demonstrates self-healing properties across a wide temperature range. The successful synthesis of the chain extender and the incorporation of both disulfide bonds and Diels–Alder (DA) bonds were confirmed using FTIR and Raman spectroscopy. The physical characteristics and self-healing performance were comprehensively evaluated through multi-scale testing and characterization, including thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA), hardness testing, mechanical tensile tests, and self-healing experiments. The underlying synergistic self-healing mechanism was subsequently elucidated. Findings showed that a higher R-value (isocyanate index) in SSDA-PU leads to over-crosslinking, while an R-value of 1.7 achieves the best overall mechanical performance, with tensile strength and elongation at break reaching 21.1 MPa and 755.17%, respectively. Additionally, SSDA-PU demonstrated the capacity for multiple healing cycles, with an initial self-healing efficiency of 90.38%, which remained notably high at 59.21% even after three damage-healing cycles. Importantly, SSDA-PU exhibited healing capabilities even at relatively low temperatures. Cracks in SSDA-PU can be effectively repaired through the synergistic action of disulfide bond exchange, hydrogen bond dissociation, and thermally reversible DA reactions. SSDA-PU also shows excellent recyclability, offering valuable insights for the practical engineering application of functional polyurethanes.
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高影响因子
COMPOSITES PART A-APPLIED SCIENCE AND MANUFACTURING
·
2026
·
IF 8.2
Dichao Ning,Mengyao Yang,Heshan Bai,Qian Shi
Vitrimer composites are composite networks with dynamic covalent bonds, opening new opportunities in scientific and industrial fields. However, vitrimer composites remain a conflict between dynamic performance and fracture resistance. Achieving both excellent dynamic performance and high fracture properties remains a formidable challenge, which limits their practical applications. Herein, we propose a multiscale reinforcement strategy to simultaneously enhance the dynamic performance and fracture properties of rubber composites by integrating dynamic covalent bonds and thiol-modified silica nanoparticles (denoted SH-silica; composites with χ wt% SH-silica are denoted SH χ%) into the rubber network. Dynamic covalent bonds along the polymer chains, at the matrix–silica dynamic interface, and between neighboring nanoparticles exhibit synergistic reinforcement across multiple length scales. The results show that the dynamic performance of the vitrimer composite reinforced with modified nanoparticles increased by 391 % compared with that of the composite with unmodified nanoparticles. Moreover, the intrinsic fracture toughness G c reached 1825 J m⁻ 2 (a 340 % increase over traditional rubber), while the fracture energy E f of notched specimens reached 1489 J m⁻ 2 (a 360 % increase over traditional rubber). This multiscale reinforcement can simultaneously enhance dynamic responsiveness, tensile properties and fracture resistance by adjusting the nanoparticle content, which is rarely achieved in traditional systems. The multiscale reinforcement strategy can be broadly applied to various rubber systems and establishes a design framework for developing the next generation of vitrimer composites.
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