SCRIPTA MATERIALIA
·
2021
·
IF 5.611
Lei Meng,Chu Xin Peng,Chen He,Fei Yen
The polarity of the magnetic susceptibility χ( T ) of ammonium alum NH 4 Al(SO 4 ) 2 •12H 2 O single crystals below its ferroelectric Curie temperature T C is identified to depend only on the cooling rate. To explain this, we consider reorienting distorted NH 4 + to carry weak magnetic and electric dipole moments that are linearly coupled. Slow cooling allows the dipole moments to align which enhances χ( T ) to become positive. However, due to energy degeneracy of rotational motion and geometric frustration of the NH 4 + , faster cooling rates render the system to become an orientational glass state causing χ( T ) to remain negative. Specific heat measurements also show the presence of excess entropy below a negative anomaly near 53 K. Our findings identify a possible new class of non-equilibrium system with potential applications in non-volatile memory devices.
研究领域:
物理学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
CRYSTAL GROWTH & DESIGN
·
2024
·
IF 3.2
Kangning Sun,Peizhuo Han,Changlin Yao,Yaning Zhao,Chuanchi Zhang,Yao Zhang,Jingke Jiang,Lei Wang
Molecules at the liquid/vapor interface have different properties, such as faster mobility and special packing structure, which can potentially affect crystal nucleation. However, the surface effect varies significantly among different small organic molecules and the underlying mechanism is still poorly understood. Herein, the effect of the surface on the crystal nucleation dynamics has been investigated in the glass-forming liquid molnupiravir (MPV) by measuring the crystal nucleation rates at the surface and in the bulk. It was found that the surface of the glass-forming liquid MPV could significantly enhance the nucleation rate by around six orders of magnitude without a polymorphic change. In comparison to water and acetaminophen with a surface enhancement factor of Js/Jv ≈ 105, the larger surface enhancement factor of MPV indicates a higher similarity between the nucleated crystal structure and the molecular packing at the surface. Our work enriches the surface-enhanced nucleation systems, which are beneficial to further understanding the stability of amorphous drugs.
研究领域:
材料科学
·
药学
✓ 已验证
产品关联
DOI
高影响因子
Materials Today Physics
·
2020
·
IF 10.443
X.N. Zhang,C. Du,M. Du,Q. Zheng,Z.L. Wu
Revealing the structure formation kinetics is a long-term challenging issue in the development of tough hydrogels, although they are significant for understanding structure-property relationship and toughening mechanism. Here, we report a series of tough and stiff poly(methacrylamide- co -methacrylic acid) hydrogels, with a focus on the structure-property relationship and structure formation kinetics. These hydrogels in a glassy state possess moderate water content and excellent mechanical properties with Young's modulus up to 200 MPa. The microstructure of the gels changes from uniform to bicontinuous and then to colloidal network as the fraction of methacrylamide, f am , increases, accounting for the ductile-brittle transition of the mechanical performances. Sequential gelation and vitrification take place in the systems with relatively low f am to form transparent gels with a homogeneous matrix, whereas colloidal jamming and coarsening occur in the systems with high f am to form opaque gels with a colloidal network structure. The structure and properties of the glassy gels are determined by the hydrogen bond complexation and the microphase separation that are strengthened by the increase in f am . Based on these findings, the mechanical properties of hydrogels with high f am can be improved by suppressing the microphase separation during the gel synthesis. Understanding the structure-property relationship and regulation strategy of both microstructure and macroscopic performance of these glassy hydrogels should be inspirative for designing other tough materials with diverse applications as structural elements in biomedical and engineering fields.
研究领域:
材料科学
·
生物医学工程
✓ 已验证
DOI
高影响因子
ACS Applied Materials & Interfaces
·
2025
·
IF 8.2
Hao Nan Qiu,Ji Lin,Li Xin Hou,Rui Xiao,Qiang Zheng,Zi Liang Wu
Various glassy hydrogels are developed by forming dense physical associations within the matrices, which exhibit forced elastic deformation and possess high stiffness, strength, and toughness. Here, the viscoplastic behaviors of the glassy hydrogel of poly(methacrylamide-co-methacrylic acid) are investigated by stress relaxation and creep measurements. We found that the characteristic time of stress relaxation of the glassy gel is much smaller than that of amorphous polymers. The varying hydrogen bond strength leads to a broad distribution of structural activation energies, which in turn affects the range of characteristic time. In the presence of water, the weak hydrogen bond associations are easily disrupted under applied strain, enhancing segmental mobility and reducing relaxation time in the preyield regime, while in the postyield regime, the relaxation time increases slightly since the chain stretching increases the energy barrier. In creep tests, the creep strain rate accelerates at the initial stage due to stress-activated segments and then decelerates as chains are extensively stretched. The stress required for structural activation during creep is much lower than the Young’s modulus of the gel, reflecting the poor structural stability. To further analyze the underlying mechanism of the glassy gel, a micromechanical model is established based on an extension on shear transformation zone theory. By incorporating a state variable for hydrogen bond density, this model can capture the intricate mechanical responses of glassy gels. Our findings reveal that glassy hydrogels are far from the thermodynamic equilibrium state, exhibiting rapid segment activation under external loading. This work provides insights to the dynamics and structural stability of glassy materials and can promote the design and applications of tough hydrogels.
研究领域:
材料科学
·
生物力学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
NEW JOURNAL OF CHEMISTRY
·
2024
·Vol. 48
·期 4
·1696-1704
·
IF 2.7
Qiurui Lin,Tao Rao,Xinyu Ma,Pan Du,Yuhan Liu,Die Luo,Xianru He
Hydrogels are promising materials, but because of their weak mechanical performance, further applications are limited. To enhance the strength of hydrogels, physical cross-linking was introduced by the use of hydrophobic unit diacetone acrylamide (DAAM) to form cross-linking points. The homopolymer of DAAM exhibited a high glass transition temperature above 80 °C, which was confirmed by DSC. The existence of the glassy and hydrophobic phases in the hydrogel was confirmed by XRD test results. The mechanical properties of the hydrogel were satisfactory, with a maximum tensile strength of 1.96 MPa, rapid recovery ability, satisfactory elasticity, and recyclability. A conductive hydrogel was prepared by introducing sodium ions, and it was used for human motion monitoring and is expected to be a promising material for flexible strain sensors.
研究领域:
材料科学
·
生物医学工程
✓ 已验证
产品关联
DOI
高影响因子
Materials Research Letters
·
2014
·
IF 0
Q. Z. Tao,C. F. Hu,S. Lin,H. B. Zhang,F. Z. Li,D. Qu,M. L. Wu,Y. P. Sun,Y. Sakka,M. W. Barsoum
Herein we present evidence for the coexistence of a Mn-rich ferromagnetic (FM) state and a Mn-poor reentrant cluster glass state in bulk, polycrystalline, layered (Cr1−x,Mnx)2GeC samples, where x is varied between 0.01 and 0.1. The Mn-poor regions form a reentrant cluster glass state below ∼30 K. The Mn-rich regions become FM at Curie temperatures that increase with increasing Mn content. The interface coupling between these two regions gives rise to exchange anisotropy and a change in sign at 20 K resulting in, rarely observed, inverted hysteresis loops.
研究领域:
材料科学
·
凝聚态物理
✓ 已验证
产品关联
DOI
CHEMISTRY OF MATERIALS
·
2023
·
IF 8.6
Weihang Li,Hui Liu,Hao Wang,Yiwen Chen,Yan Peng,Haitao Wu,Yujia Hou,Yue Huang,Zhaoyang Yuan,Bangjiao Ye,Hongjun Zhang,Jinrong Wu
Loose connective tissue that widely exists in the human body is very tough and healable, due to the unique network formed by hyperbranched and linear fibers. Inspired by such structure, we develop a class of tough and healable polymeric glasses (THGs) by tailoring amine-carboxylate salt bridges between a hyperbranched polymer and high-molecular-weight linear copolymers. The high density of salt bridges leads to high yield strength (up to 49.7 MPa) and Young’s modulus (1.1 GPa) of THGs. Meanwhile, the large free volume of the hyperbranched polymer and the molecular entanglements of the linear copolymers enable outstanding toughness (up to 91.9 MJ/m3), outperforming most commercial glassy polymers. More interestingly, THGs can be readily healed below and around the glass-transition temperature after mechanical damage. Therefore, this biomimetic approach enables the development of glassy polymers with combination of high strength, excellent toughness, and self-healing ability.
研究领域:
材料科学
·
生物医学工程
✓ 已验证
产品关联
DOI
高影响因子
EUROPEAN POLYMER JOURNAL
·
2023
·
IF 6
Weiming Yang,Quanxi Yi,Fanqi Liu,Xianjie Pan,Yanning Zeng
Epoxy vitrimers with robust mechanical properties, facile self-healing and recycling are highly desired and maintain a challenge. In the present work, a series of novel itaconic acid (IA) based epoxy vitrimers incorporated dynamic β- hydroxy ester bonds and boronic ester bonds were successful fabricated using IA derivate with double terminal epoxy and 2,2′-(1,4-phenylene)bis[5-methyl-1,3,2-dioxaborinane-5-carboxylic acid] (BDCB) with two carboxyl groups by a reaction between epoxy and carboxyl. The obtained IA-based epoxy vitrimer possesses comparable thermal stability ( T 5d = 255 °C) and mechanical properties (tensile strength = 68.3 MPa), elongation at break = 16.8 % and toughness = 6.43 MJ·m −3 ) to conventional epoxy resins, due to the rigid network frameworks. Meanwhile, the IA-based epoxy vitrimer show excellent self-healing, welding, physical reprocessing and chemical recycling due to the rearrangement of network typology by thermally-induced dioxaborolane metathesis and transesterification. The self-healing efficiency of the surface scratch reaches 100% at 150 °C for 2 h. High welding efficiency is observed as high as 84.2%. The mechanical properties of both the reprocessed and the chemical recycled IA-based epoxy vitrimers maintain 85.5% and 78.9% of the original one, respectively. The IA-based epoxy vitrimers can be applied in recycled adhesion with the adhesion strength of 16.2 MPa.
研究领域:
材料科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
Polymers
·
2021
·Vol. 13
·期 20
·3538
·
IF 4.329
Jiawei Li,Weiming Yang,Zhao Ning,Bin Yang,Yanning Zeng
Rosin is an abundant natural product. In this paper, for the first time, a rosin derivative is employed as a monomer for the preparation of polyurethane vitrimers with improved properties. A novel rosin-based polyurethane vitrimers network was constructed by the reaction between isocyanates (HDI) as curing agent and monomers with alcohol groups modified from rosin. The dynamic rosin-based polyurethane vitrimers were characterized by FTIR and dynamic mechanical analysis. The obtained rosin-based polyurethane vitrimers possessed superior mechanical properties. Due to the dynamic urethane linkages, the network topologies of rosin-based polyurethane vitrimers could be altered, contributing self-healing and reprocessing abilities. Besides, we investigated the effects of healing time and temperature on the self-healing performance. Moreover, through a hot press, pulverized samples of 70%VPUOHcould be reshaped several times, and the mechanical properties of the recycled samples were restored, with tensile strength being even higher than the of that of the original samples.
研究领域:
材料科学
·
高分子化学
·
可持续材料
✓ 已验证
DOI
高影响因子
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2025
·
IF 3.9
Wei Zhang,Yueshuang Wang,Ai Li,Yadong Lv,Guangxian Li,Qi Yang,Miqiu Kong
In this work, different fractions of poly(sebacic acid anhydride) (PSA) are used to control the molecular networks of epoxy vitrimers synthesized from diglycidyl ether of bisphenol A (DGEBA) and glutaric anhydride (GA) under the initiation of 1,4-benzenedimethanol (BDM). It is found that the toughness and self-healing performance of the modified epoxy vitrimer are significantly improved by the introduction of PSA with a long alkyl chain. Particularly, with the addition of 10 wt % PSA, the impact toughness and elongation at break of the epoxy vitrimer are increased by 1966.2 and 855.2%, respectively; meanwhile, the self-healing and reprocessing performances are improved. Furthermore, relative mechanisms are proposed in terms of the reaction of PSA with a long alkyl chain in the molecular network structure. Specifically, under the initiation of the hydroxyls of BDM, not only carboxyl groups can be formed via the ring-opening of GA but also sebacic acid (SA) can be formed via the reaction of the anhydride of PSA, so that abundant dicarboxylic acids can react with the epoxide groups of DGEBA, and thus PSA with a long alkyl chain can be introduced into the molecular networks of the epoxy vitrimer. As a result, the transesterification and the relaxation of the molecular networks are advanced, and the toughness is significantly improved. This work supplies a simple method to prepare toughened catalyst-free epoxy vitrimers with self-healing and reprocessing properties.
研究领域:
材料科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
MACROMOLECULES
·
2024
·
IF 5.1
Haosheng Ye,Aizhen Li,Guanqiao Li,Kang Li,Jing Zhang,Dong Wang,Suprakas Sinha Ray,Hengti Wang,Yongjin Li
Rubber-toughened glassy polymers, researched as a prominent toolkit to fabricate high-performance plastics, are usually confronted with a great loss of tensile strength at the point of apparent yielding. Exploiting advanced plastic nanoalloys with high toughness and small stress difference (Δσ) between yielding and tensile platforms at high-strain levels is extremely being pursued yet challenging. Taking glassy poly(l-lactide) (PLLA) as an example, here, a viable and universal approach is discovered to elaborate supertoughened nanoalloys with significantly depressed yielding behaviors by virtue of elastomeric nanobelts to replace conventional rubber droplets in a glassy matrix by a simple reactive processing strategy. Stereocomplex crystal (SC)-immobilized EGMA, prepared by cocrystallization of enantiopure PDLA-/PLLA pairs respectively pregrafted onto EGMA chains, is used to toughen PLLA. Therefore, the structure of the elastomer, from droplets and shells to nanobelts in the PLLA matrix, can be achieved. Such controllable morphology allows for the corresponding nanoalloys with significantly enhanced notched impact strength (from 5.7 to 60.2 to 91.3 kJ/m2) and shortened Δσ (from 17.5 to 15.8 to 6.8 MPa). Furthermore, tricontinuous morphology integrates penetrative elastomeric nanobelts (EGMA), glassy polymers (PLLA), and SC phases, which are achieved by adjusting SC moieties. The authors demonstrate that the resulting nanoalloy integrates superior performance (toughness, heat resistance, and crystallization rate) and stress leveling-off without fully undergoing real yielding (Δσ = 1.4 MPa), surpassing most elastomer-toughened PLA alloys. The morphology development and underlying origin of the impact/deformation mechanism are elucidated. To our knowledge, this is the first time that the validity of such supertoughened glassy polymer alloys with significantly necking-suppressed deformation has been demonstrated. The versatile strategy can be further extended to arbitrary engineering plastics, including PET, PBT, and nylon, providing a paradigm in the development of advanced nanoalloys, which is quite challenging via existing industrial technologies.
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 A-APPLIED SCIENCE AND MANUFACTURING
·
2021
·
IF 7.664
Quan Wu,Xinyu Cui,Chenzhong Mu,Jun Sun,Xiaoyu Gu,Hongfei Li,Sheng Zhang
Polylactic acid (PLA) with eco-friendliness exhibits extensive potential applications. In order to enhance fire-resistance of PLA, this manuscript reports the preparation of boron-containing ammonium polyphosphate (B-APP) using 3-aminophenyl boronic acid and ammonium polyphosphate through ion exchange reaction , and incorporated into PLA matrix. The limiting oxygen index (LOI) of PLA-5% B-APP was increased from 19.2% to 29.4% and a UL-94 V-0 rating. In the cone calorimeter tests, PLA-5% B-APP presented a total heat release (THR) reduction from 81 MJ·m −2 to 67 MJ·m −2 and an improvement from 1.6% to 6.7% in char residue comparing with PLA. The mechanism of B-APP was mainly ascribed to the formation of glassy char layers to block the heat and oxygen transfer. For mechanical properties , it could be also found that the elongation at break and impact strength were improved at the presence of 5% B-APP.
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
危险品化学品经营许可证（带存储）