Inorganic Chemistry Frontiers
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2021
·Vol. 8
·期 12
·3149-3155
·
IF 6.569
Xiuwei Sun,Shumei Liu,Qingyin Wu,Shan Zhang,Hongrui Tian,Xue Bai,Zhuo Li,Ying Lu,Shuxia Liu
Polyethyleneimine (PEI) is expected to become a new type of proton conduction booster due to its high density amine and extremely high flexibility. Herein, a nanofiber membrane (eHPW-PEI) composed of PEI and phosphotungstic acid (H3PW12O40, HPW) was prepared by electrostatic spinning using polyvinylpyrrolidone (PVP) as an adhesive. In eHPW-PEI, the continuous H-bond network formed by HPW-PEI acid–base pairs, the segmental movement of highly flexible PEI and the well-tuned pathway of 1D nanofibers jointly prompt the fast transfer of protons under high temperature and low humidity conditions. The proton conductivity of eHPW-PEI with 25 wt% HPW (eHPW-PEI1) reached 1.6 × 10−3 S cm−1 at 85 °C and 60% relative humidity (RH) and 3.7 × 10−3 S cm−1 at 135 °C. This is the first time that the segmental movement of a highly flexible polymer is utilized to accelerate proton transfer, which may be considered as a ‘proton-escalator’.
研究领域:
材料科学
·
能源科学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF APPLIED POLYMER SCIENCE
·
2023
·Vol. 141
·期 11
·e55104
·
IF 3
Yifang Wang,Boxue Du,Xiaoxiao Kong,Xiaolong Li
In this paper, three epoxy resin systems commonly used in power equipment are prepared to obtain cross-linked networks with structural differences. The relationship between microscopic structures and dielectric properties of epoxy resins is investigated and discussed. Experimental results show that the polarization and conductance losses are inhibited in the anhydride-cured systems with methyl groups. The molecular dynamics (MD) simulation shows that rigid anhydride structures (such as methyl groups) play a major role in reducing the local segment mobility and increasing the free volume at cross-linking points. The decrease in local segment mobility has been confirmed by the decrease of mean square displacement (MSD) at the cross-linking points, which is consistent with the change of measured polarization and conductance loss. In the glassy state, the dielectric properties of different anhydride-cured systems can be reflected by local MSD at the cross-linking points. At high temperatures near the glass transition temperature, both the free volume and network mobility increase significantly, which reflects the increased dielectric relaxation strength and conductance loss. The understanding of the structure–property relationships could provide a theoretical foundation for epoxy modification in a controlled manner for power equipment applications.
研究领域:
材料科学
·
电气工程
✓ 已验证
产品关联
DOI
高影响因子
Magnetic Resonance Letters
·
2021
·
IF 0
Kaleem-Ur-Rahman Naveed,Li Wang,Haojie Yu,Qian Zhang,Wei Xiong,Raja Summe Ullah,Ahsan Nazir,Muhammad Usman,Shah Fahad,Amin Khan,Md Alim Uddin,Di Shen
Study of the segmental mobility of polymer chains is important when the polymer is used as drag reduction agents of crude oil. Electron spin resonance (ESR) spectroscopy can provide important information about segmental dynamics of polymer chains, which is related to their microenvironment. In this article, we employed an amphiphilic polymer to study the effect of hydrophilic/hydrophobic balance of the polymers on the segmental motion of polymer chains. Poly(styrene- co -maleic acid) (PSMA) was spin labeled with 4-amino TEMPO radicals by increasing the concentration of radical moiety on the polymer chains. The PSMA and spin labeled-PSMAs (SL-PSMAs) were characterized by nuclear magnetic resonance (NMR), Fourier transform infrared (FT-IR) spectroscopy, Cyclic voltammetry (CV) and ESR techniques. Inter-polymer complexes (IPCs) of SL-PSMA-2 were prepared by employing polyethylene glycols (PEGs) of varying molecular weights. The results showed that the increased hydrophobic interactions of nitroxide radicals on the SL-PSMAs’ chains reduced the rotational mobility of spin labels and the random coil-to-globular transition of polymer chains occurred at higher pH value for SL-PSMAs, which showed a slow motion component in the ESR spectra of SL-PSMAs. Further, by increasing the molecular weight of PEGs in IPCs the complexation was increased, which also reduced the rotational motion of spin labels due to interpolymer hydrogen bonding causing a slow motion component in the ESR spectra.
研究领域:
高分子化学
·
物理化学
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材料科学
✓ 已验证
DOI
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
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材料工程
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软物质物理
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化学合成
✓ 已验证
DOI
高影响因子
JOURNAL OF RHEOLOGY
·
2022
·Vol. 66
·期 6
·1113-1123
·
IF 4.534
Yang Huanhuan,Wu Shilong,Chen Quan
This study examines the linear viscoelasticity of double-associative ionomers based on poly(hexyl methacrylate). The ionomer samples are unentangled and contain a fixed number of ionic stickers per chain, f ion ≅ 4 , but a varied number of hydrogen-bonding stickers per chain, f H = 5.5–27. Increasing f H has distinct effects on the glassy and rubbery dynamics. On the one hand, the glassy relaxation mode distribution broadens, and the glassy-to-rubbery transition region delays significantly with increasing f H . On the other hand, the delay of the ionic dissociation and, accordingly, the terminal relaxation (activated by continuous ionic dissociations) are much weaker. This contrast suggests that the ionic dissociation is not only activated by the segmental motion of the main backbone but is also partly activated by the motion of the side chains that is less dependent on f H .
研究领域:
高分子科学
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材料科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF MEMBRANE SCIENCE
·
2025
·
IF 9
Hanchao Gao,Linkang Gu,Shuxia Duan,Zhaopeng Xia,Kai Zhang,Wenxiu Yang,Chenwei Li,Xinyu Zhang,Yong Liu
Rational design molecular-level crosslinked structures of electret membranes remain a significant challenge for stable electrostatic filtration of airborne particles. Here, rigidity-tailored crosslinked networks, designed by modulating the molecular rigidity of interchain covalent bonds in crosslinked poly(styrene-co-maleic anhydride) (CS-IDDA), are exploited to function as deep traps to immobilize charges in electret membranes. The trapping sites capture charge carrier injected by corona discharging, obtaining deep-trapped electret CS-IDDA membranes. The electret CS-IDDA membranes maintain 99.83 % filtration efficiency after prolonged exposure to 95 % relative humidity environment. The remarkable filtration efficiency stability is attributed to deep-trapped charges with high energy level and improved charge retention enabled by restricted segmental mobility. Noteworthily, deep-trapped charges are anchored by connectivity defects and spatial inhomogeneity within rigid crosslinked networks. Moreover, the rigid crosslinked networks confine molecular chain movement by reducing interchain spacing and free volume, effectively suppressing charge migration, and hence dominate stable electrostatic capture of airborne particles. This study highlights the significance of modulating the molecular-scale rigidity engineering of crosslinked networks to effectively design electret membranes for advance air purification and safeguarding public health security.
研究领域:
材料科学
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高分子化学
·
环境工程
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静电学
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纳米技术
✓ 已验证
产品关联
DOI
高影响因子
Energy Storage Materials
·
2021
·
IF 17.789
Lei Zhong,Shuanjin Wang,Min Xiao,Wei Liu,Dongmei Han,Zhifeng Li,Jiaxiang Qin,Yuning Li,Shichao Zhang,Sheng Huang,Yuezhong Meng
Eliminating interfacial incompatibility and creating smooth ions/electrons transport at the interfaces of cathode│electrolyte│anode, are keys for the practical application of all-solid-state lithium-sulfur battery (ASSLSB). Here, we report a fully integrated-ASSLSB ( i -ASSLSB) whose interfacial resistances are suppressed by the segmental motion of polyethylene oxide in hierarchical polymer electrolyte throughout the whole battery system. The mobility of ethylene oxide segments and strength of polyelectrolyte membranes can be controlled by the cross-linking degree of single-ion conductive polyelectrolyte. Such a i -ASSLSB without distinct interface achieves liquid-state-level lithium-ion diffusion coefficient of 2.4 × 10 −12 cm 2 s −1 and demonstrates a remarkable capacity up to 1428 mA h g −1 at 0.05 C and 100-cycle stability at 0.1 C. This work promises a valuable technical approach of interface modulation for high-performance all-solid-state lithium-sulfur batteries.
研究领域:
材料科学
·
电化学
·
储能技术
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固态电池
·
聚合物化学
✓ 已验证
DOI
高影响因子
INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
·
2024
·
IF 7.7
Liping Mei,Zhijie Zhu,Caihong Wang,Chengyi Sun,Peirong Chen,Huimei Cai,Xu Chen,Xianfeng Du
The molecular motion of starch at different glycerol concentrations (0, 20, 50, and 80 %) was investigated using Electron Paramagnetic Resonance (EPR) spectroscopy. Fourier-transform infrared (FTIR) spectroscopy and 1 H nuclear magnetic resonance ( 1 H NMR) spectroscopy confirmed that hydroxyl groups at the C2 and C3 positions of glucose units in corn starch (CS), waxy corn starch (WCS), and high amylose corn starch (HCS) were labeled with 4-amino-TEMPO. The crystallinities of CS, WCS, and HCS after spin-labeling decreased from 30.68 % to 3.21 %, 39.36 % to 1.65 %, and 28.54 % to 8.08 %, respectively. The pseudoplastic fluid properties of the spin-labeled starch remained shear-thin at different glycerol concentrations. EPR revealed the fast- and slow-motion components of the spin-labeled starch molecules dispersed in water. At a glycerol concentration of 20 %, the slow-motion component disappeared, indicating a faster rotational motion of the starch chain segments. As the glycerol concentration increased to 50 and 80 %, the rotational motion slowed because of high viscosity. In particular, the mobility of the spin-labeled WCS chains increased owing to easier access of glycerol and water to the branched structure. This study directly observed the dynamics of the molecular behavior of starch in glycerol-water systems.
研究领域:
食品科学
·
物理化学
·
材料科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
危险品化学品经营许可证（带存储）