Journal of Materials Chemistry A
·
2020
·Vol. 8
·期 22
·11261-11274
·
IF 11.301
Xiwei Xu,Songqi Ma,Sheng Wang,Jiahui Wu,Qiong Li,Na Lu,Yanlin Liu,Jintao Yang,Jie Feng,Jin Zhu
Covalent adaptable networks (CANs) provide a promising approach to solve the issue of recycling thermosets due to their dynamic cross-linked networks. However, CANs are susceptible to creep at relatively low temperatures, and their chemical stability is also inevitably doubtful. Here, we designed novel dihydrazone CANs by cross-linking a dihydrazone-containing epoxy monomer, which was synthesized from the condensation of a lignin derivative vanillin and hydrazinium hydrate, followed by a reaction with epichlorohydrin. Besides the excellent malleability and reprocessability, the dihydrazone CANs exhibited a high initial creep temperature of ∼105 °C, which was ascribed to the superior stability of the hydrazone bond at around 100 °C and favorable hydrazone exchangeability at elevated temperatures. Meanwhile, the degradation of the dihydrazone CANs exhibited temperature, solvent, and acidity dependence. Moreover, on account of the high antibacterial properties of the hydrazone bond, the CANs presented a high killing rate (95.8%) for Gram-negative bacteria (E. coli). Thus, this work discloses an effective dynamic covalent motif for the development of CANs with excellent dimensional stability, chemical resistance, and intrinsic antibacterial properties.
研究领域:
材料科学
·
生物化学
✓ 已验证
产品关联
DOI
高影响因子
POLYMER
·
2025
·
IF 4.5
Xiangyuan Meng,Huifang Ma,Yaping Ma,Chenguang Liu,Aihua He
High-temperature resistant shape memory polyolefins, which also exhibit resistances to creep and raw petroleum, are highly crucial for the pipelines in severe environments, like high temperature, high pressure and petroleum medium. Herein, a series of crosslinked polybutene-1 alloys (PBA-X) were firstly fabricated, which presented excellent high-temperature resistances to creep and raw petroleum at 85 °C, as well as outstanding shape memory behaviors like 93.7-100.0 % shape recovery ratio ( R r ), 90.6-98.4 % shape fixation ratio ( R f ), and easy recovered from varied programmed three-dimensional (3D) shapes through thermal stimulation. PBA-X are anticipated to offer significant potential as innovative pipeline lining materials for deep-ocean petroleum transportation systems.
研究领域:
材料科学
·
石油化工
✓ 已验证
产品关联
DOI
高影响因子
Materials Today Chemistry
·
2021
·
IF 8.301
Y. You,M.R. Fu,M.Z. Rong,M.Q. Zhang
Thermoresponsive covalent adaptive networks (CANs) have attracted increasing research attention because of their temperature-dependent reversibility, which endows the materials with versatile smart functionalities including intrinsic self-healability not available for traditional thermosets . Nevertheless, the associated reduction in creep resistance of this type of CANs limits their practical application. Here in this work, we demonstrate that the reversibility and dimensional stability can be combined via interlocking the thermoresponsive network with an ultraviolet-responsive network. The two types of networks are, respectively, crosslinked by orthogonal reversible Diels-Alder (DA) bonds and coumarin. Owing to the interlocked architecture, the latter single network can be uniformly distributed in the former, restricting the chain movement and enhancing the creep resistance even when the former is decrosslinked at elevated temperature as a result of retro-DA reaction. Meanwhile, the ultraviolet-responsive network plays the role of a photo-reversible switch. Its decrosslinking on exposure to 254 nm ultraviolet (UV) light and recrosslinking under a UV irradiation of 350 nm lead to repeated releasing and reimposing of the restraints on the neighboring thermoresponsive network. By using this smart habit, the material can either be conditionally self-healed with moderate healing efficiency or completely self-healed depending on whether only DA bonds or both DA bonds and coumarin are triggered. More importantly, the conflicting properties, that is, creep resistance and reversibility of the CANs are thus united. The proposed strategy provides a facile way for overcoming the weaknesses of CANs while maintaining the advantage.
研究领域:
材料科学
·
高分子化学
✓ 已验证
产品关联
DOI
高影响因子
COMPOSITES PART B-ENGINEERING
·
2025
·
IF 14.2
Xin Gou,Changrong Liao,Yong Zhang,Pei Li,Shipan Lang,Chao Zhang,Shengkai Hu,Ning Yu,Chunbao Li,Jun Yang
Flexible pressure sensors face an irreconcilable trade-off among linearity, sensitivity, and signal stability due to viscoelastic creep. Inspired by the gradient modulus characteristics of human skin, this study employs electrospinning to construct a heterogeneous structure composed of a high-modulus nanofiber network embedded in a low-modulus ionic gel. This structure mimics epidermal rigidity (high-modulus nanofiber layer), dermal viscoelasticity (fiber-gel hybrid), and hypodermal compliance (soft ionic matrix) to synergistically redistribute stress and suppress ion migration. The sensor achieves breakthrough performance: a wide linear range (1 MPa) with near-perfect linearity (R 2 = 0.999) and ultrahigh sensitivity (81.3 kPa -1 ), yielding a record linear sensing factor (LSF, 81,300). Simultaneously, it exhibits ultralow creep (1.76% signal drift under sustained loading)—96.8% lower than non-structured iongels—enabled by nanofiber-restricted ion pathways. Theoretical modeling reveals a dynamic compensation mechanism where pressure-induced changes in dielectric properties, contact area expansion, and electric double-layer thinning interact linearly. Laboratory validation demonstrates high-fidelity plantar pressure monitoring during gait cycles and machine learning-based prediction of vertical ground reaction forces with exceptional accuracy (R 2 > 0.95). This work establishes a new design paradigm for high-precision flexible sensing by fundamentally resolving long-standing material limitations.
研究领域:
生物医学工程
·
柔性电子学
·
传感材料
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康复工程
·
足底压力监测
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可穿戴设备
·
力学传感
✓ 已验证
产品关联
DOI
高影响因子
POLYMER
·
2023
·
IF 4.6
Mei-Juan Xie,Chang-Cheng Wang,Rong Zhang,Jian Cao,Mao-Zhu Tang,Yun-Xiang Xu
Inhomogeneous network construction is a useful strategy to solve the trade-off between mechanical strength and creep in vitrimer rubbers. But it is still lack of tools to tune the mechanical properties and network dynamics of this new system. In this paper, uneven distribution of functional groups was realized by sequential coordination polymerization of myrcene and isoprene and epoxidation . The following epoxidation and curing generated VMI-x samples with inhomogeneous network. Polyisoprene was used to prepare control samples called VPI-x with homogeneous network. Different lengths of dicarboxylic acid crosslinkers (SA = succinic acid, HA = heptanedioic acid, DA = decanedioic acid) were used to probe their effects on dynamic behaviors, mechanical properties and recyclability . Morphological test and nanomechanical mapping confirmed the inhomogeneous feature of VMI-x samples. For both inhomogeneous and homogeneous samples, SA and DA crosslinkers brought higher tensile strength and modulus, earlier SIC phenomenon and higher orientation percentage of amorphous molecular chains than those of HA, which are ascribed to extra permanent cross-linking existing in SA samples and transition entanglements existing in DA samples. However, the constrain effect of SA crosslinker is too strong in inhomogeneous network to sacrifice the extensibility, which is much smaller than those of HA and DA. SA and DA samples also present restricted segmental motion and superior creep resistant properties compared to HA samples according to the results of broadband dielectric spectroscopy and DMA test. Differently, at high temperature above 130 °C, the stress relaxation, topology freezing transition temperature (Tv) and recycling efficiency of strength are dominated by the crosslinker length monotonically, probably due to the disentanglement of DA crosslinkers. Compared to homogeneous network, inhomogeneous ones showed obvious enhanced mechanical properties, lower hysteresis, quicker segmental relaxation, lower creep and quicker network relaxation. This work demonstrates that crosslinker lengths could tune the vast aspects of vitrimer elastomers and is a non-negligible factor to determine their properties, especially for those with inhomogeneous networks.
研究领域:
高分子科学
·
材料工程
·
软物质物理
·
化学合成
✓ 已验证
DOI
高影响因子
Advanced Science
·
2024
·
IF 14.3
Kaifeng Chen,Hua Yang,Ang Wang,Linsen Tang,Xin Zha,Ndeutala Selma Iita,Hong Zhang,Zhuoxuan Li,Xinyu Wang,Wei Yang,Shaoxing Qu,Zongrong Wang
Signal drift and hysteresis of flexible piezoresistive sensors pose significant challenges against the widespread applications in emerging fields such as electronic skin, wearable equipment for metaverse and human-AI (artificial intelligence) interfaces. To address the creep and relaxation issues associated with pressure-sensitive materials, a highly stable piezoresistive composite is proposed, using polyamide-imide (PAI) fibers as the matrix and in situ grafted-polymerized polyaniline (PANI) as the semi-conducting layer. The PAI with large rigid fluorenylidene groups exhibits a high glass transition temperature of 372 °C (PAI 5-5), which results in an extremely long relaxation time at room temperature and consequently offers outstanding anti-creep/relaxation performances. The enhancement of PAI-PANI interfacial bonding through in situ grafting improves the sensor reliably. The sensor presents high linear sensitivity of 35.3 kPa −1 over a pressure range of 0.2–20 kPa, outstanding repeatability, and excellent dynamic stability with only a 3.8% signal deviation through ≈10 000 cycles. Real-time visualization of pressure distribution is realized by sensor matrices, which demonstrate the capability of tactile gesture recognition on both flat and curved surfaces. The recognition of sitting postures is achieved by two 12 × 12 matrices facilitated by machine learning, which prompts the potential for the augmentation of smart driving.
研究领域:
材料科学
·
传感器
·
人工智能
·
汽车工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Materials Chemistry Frontiers
·
2022
·Vol. 6
·期 4
·503-511
·
IF 8.683
Jinshi Han,Yawei Zhou,Guanghang Bai,Wei Wei,Xiaoya Liu,Xiaojie Li
Thermoset polyurethanes have been applied in various fields by virtue of their outstanding properties. However, the thermosets cannot be recycled due to their permanent crosslinking structure, which exerts a detrimental influence on the environment. Recently, the upsurge in the field of covalent adaptable networks (CANs) has attracted tremendous attention. Despite many efforts being dedicated to the design of CANs, the creep resistance of CANs holds much room for further improvement at high temperature. Here, we designed a kind of azine chain extender and prepared a series of dynamic polyurethane networks in varying azine proportions. The azine-containing CANs possess high creep temperature of ∼100 °C attributed to the stability of the azine moieties. Besides, the azine-containing polyurethanes also exhibit outstanding mechanical properties and reprocessability due to the conjugated structure and exchangeability of the azine moieties. The azine-containing polyurethanes also present good antibacterial properties as the azines are a special category of Schiff base. This work demonstrated that azine moieties could enhance the creep resistance, which is a long-term and crucial issue for dynamic covalent polyurethanes and endows the dynamic covalent polyurethane networks with excellent mechanical properties and intrinsic antibacterial properties.
研究领域:
材料科学
·
聚合物化学
·
可持续材料
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）