Polymer Chemistry
·
2025
·
IF 3.9
Lang Shuai,Guangwei Xu,Jianglong Li,Jianlong Wen,Boyu Ding,Shui Yu,Yingying Xu,Yijing Nie
To meet environmental challenges and advance sustainable development, it has become imperative to develop engineering glassy polymers with autonomous and room-temperature self-healing capability. Although several strategies for achieving self-healing in glassy polymers have been reported, the underlying mechanism dominating the self-healing process below glass transition temperature (Tg) remains elusive. Herein, we synthesized hyperbranched polyurethanes (HPUs) to leverage their abundant hydroxyl end groups for constructing a dense hydrogen-bonding network. The HPUs exhibit good self-healing ability below Tg (the self-healing efficiency can reach ~50% and ~90% after 0.5 h and 48 h of self-healing, respectively). Both experimental and simulation results revealed that a large number of end groups and branching units in the HPUs undergo secondary relaxation, and can move locally at temperatures below Tg, which is beneficial for the sub-Tg self-healing. In addition, the HPUs containing lower hydrogen bond contents exhibit stronger sub-segment mobility and higher self-healing efficiency, indicating that the mobility of sub-segmental units plays a more important role in promoting the self-healing of glassy hyperbranched polymers rather than the recombination of hydrogen bond content.
研究领域:
高分子科学
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材料化学
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自修复材料
·
软物质物理
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DOI
高影响因子
POLYMER
·
2017
·
IF 3.684
Lala Rukh Sidra,Guofei Chen,Nafeesa Mushtaq,Lubo Xu,Xiaoqi Chen,Yantao Li,Xingzhong Fang
To extend the upper operating temperature range of melt processable PIs , two series of end-capped copolyimides based on hydroquinone diphthalic anhydride (HQDPA) isomers were designed by varying the contents of appropriate diamines. Thus, copolyimides PI-(0a∼20a) based on 3,3′-HQDPA were prepared by varying the ratio of rigid 2-(4-aminophenyl)-5-aminobenzimidazole (BIA) and flexible 4,4′-oxydianiline (ODA). The resulting copolyimides demonstrated good properties, such as excellent solubility, high T g ranging from 328 to 354 °C as determined by dynamic mechanical analyzer (DMA), besides, exhibited good thermal stability based on 5% weight loss temperature ( T 5% ) of 502–514 °C and low melt viscosity in the range of 291–935 Pa·s. Most importantly, PI-20a showed a good combination of low melt viscosity simultaneously with significantly high T g (328 °C). Furthermore, this system was modified by copolymerization with different feed ratio of 4,4′-HQDPA isomer and produced another series PI-(20a∼20e), that exhibited high T g in the range of 315–330 °C with T 5% of 502–543 °C and minimum complex viscosity in the range of 291–479 Pa·s. All PIs form tough and flexible films that have remarkable tensile strength and moduli in the range of 93–116 MPa and 3.7–4.7 GPa, respectively.
研究领域:
材料科学
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高分子化学
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DOI
高影响因子
COMPOSITES SCIENCE AND TECHNOLOGY
·
2023
·
IF 9.1
Xiaofei Wang,Yang He,Xinli Xiao,Jinsong Leng
Shape memory polyimide (SMPI) is one of the most promising intelligent materials and has a high potential for deformable flexible electrodes , intelligent thermal management devices, and high temperature active deployable structures , etc. In this paper, silane-modified AlN nanoparticles (M-AlN) are composited with SMPI matrix resin to prepare fast-response high-T g shape memory composites. Besides, nano-sized AlN and micron-sized Al 2 O 3 are used to construct “micro-nano” synergistic thermal conduction networks, in which the AlN acted as the “thermal conduction island”, and the Al 2 O 3 acted as the “thermal conduction bridge”. The results show that the in-plane thermal conductivity of Al 2 O 3 /M-AlN/M-SMPI-2 is 5.99 W m −1 K −1 , compared with SMPI, its thermal conductivity increases by 91%. In addition, the shape transition temperature of Al 2 O 3 /M-AlN/M-SMPI-2 was higher than that of pure SMPI, which was at 426 °C, and the thermal response shape recovery speed is also greatly improved by 433%, which can be used in rapid-actuating and high temperature active deformation structure .
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高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2022
·
IF 16.744
Jinghong Liu,Xiaoqing Zhang,Sihui Liu,Caihong Lei
Epoxy resins often age during high-temperature use, causing a drop in T g and a number of safety problems. Currently, no specific reports addressing this T g drop are available. Here, we proposed that the T g drop could be prevented by allyl modification, and designed a series of epoxy monomers containing allyl to demonstrate this view. First, the influence of allyl groups on epoxy monomers was evaluated. It was found that allyl groups could reduce the viscosity of the monomers and the curing rate. These monomers were cured by DDM into resin (virgin resin) and treated at 285 °C for 6 h (treated resin) until the double bond was consumed. By comparison, it was found that although the introduction of allyl groups reduces the T g of the virgin resin, it does not adversely affect the thermal degradation temperature ( T d5% ). The T d5% and T g of the allyl-containing treated resin did not drop significantly like those of the treated resin without allyl. Specially, the T d5% and T g of an allyl-rich resin increased by + 49 and + 289 °C, respectively. According to further study of the network generated by allyl groups, the allyl group in the para position (relative to the glycidyl ether group) would produce greater cross-linking, whereas the intramolecular ring formation in the ortho position results in an imperfect network of the new resin. Finally, through qualitative analysis of the entire resin network, we believe that this is a result of the high-temperature destruction of the epoxy network and the formation of an allylic network.
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高影响因子
RENEWABLE ENERGY
·
2023
·
IF 8.7
Yun Zhang,Chuanbiao Zhang,Wenjuan Li,Qiuping Xiao,Fengyuan Jiao,Sen Xu,Yanhua Lan,Yizheng Fu,Chi-Min Shu,Weiguo Cao
Stearic acid provides a basis for developing renewable energy, such as solar energy and biomass energy. A thermogravimetric-infrared spectroscopy (TG-IR) experimental test is conducted to obtain the thermal decomposition progress and the main gaseous products of stearic acid. The result shows that small gaseous products (H 2 O, CO 2 , CO, alkanes, olefins , etc.) are released. Furthermore, the method of reactive molecular dynamics simulation (ReaxFF-MD) is utilized to look into the pyrolysis reaction mechanism of stearic acid. The main pyrolysis products of stearic acid received by ReaxFF-MD are C 2 H 4 , H 2 , C 2 H 2 , CH 4 , H 2 O, CO 2 , and CO, consisting of the result of the TG-IR test. The effect of the simulated system density and temperature on the distribution of main products is also explored. Also, the thermal kinetic analysis is conducted by the initial consumption of stearic acid under different temperatures. The primary reaction mechanism of stearic acid pyrolysis is that the stearic acid molecules dissociate through C–C bonds break to generate C 2 H 4 , CH 4 , C 2 H 2 , C 3 H 6 , and other small molecules and radicals, and a typical reaction mechanism scheme of stearic acid pyrolysis is presented. The results provide a reference for explaining the macroscopic explosion characteristics of dust at the microscopic mechanism level.
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高影响因子
RSC Advances
·
2014
·Vol. 4
·期 68
·36183-36188
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IF 3.708
Ying-Ying Zhang,Xing-Hong Zhang,Ren-Jian Wei,Bin-Yang Du,Zhi-Qiang Fan,Guo-Rong Qi
The selective copolymerization of CO2 and an epoxide to form fully alternating polycarbonates is a great challenge via catalysis with the zinc–cobalt(III) double metal cyanide complex [Zn–Co(III) DMCC]. We describe the first perfectly alternating copolymerization of CO2 with a bio-based epoxide. The resultant polycarbonate had a low Tgs of −38 to −44 °C and two end hydroxyl groups, which were then used to initiate ring-opening polymerization of L-lactide via metal-free catalysis, affording a biodegradable triblock copolymer. This study provides a new platform copolymer for making various advanced polymers with biodegradable properties.
研究领域:
材料科学
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催化化学
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高分子化学
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DOI
高影响因子
RSC Advances
·
2016
·Vol. 6
·期 30
·25302-25310
·
IF 3.289
Nafeesa Mushtaq,Guofei Chen,Lala Rukh Sidra,Xingzhong Fang
To investigate the asymmetric effect of the naphthalimide moiety on the thermal, mechanical, optical properties and water uptake of polyimides (PIs), two novel asymmetric diamines, 4-(4-aminophenoxy)-N-amino-1,8-naphthalimide 3 and 4-(4-aminophenoxy)-N-(4-aminophenyl)-1,8-naphthalimide 4 were synthesized. Two series of PIs 5b–e and 6a–e were prepared from diamines 3 and 4 by solution polymerization method, respectively. The resulting polyimides demonstrated good solubility, high glass transition temperature (Tg) of 311–421 °C and good thermal stability based on the 5% weight loss temperature (T5%) of 435–563 °C in nitrogen. These PIs also exhibited good mechanical properties with tensile strengths of 107.3–172.2 MPa, tensile moduli of 2.8–4.9 GPa, and elongations at break of 2.9–9.1%. The water uptake of PIs was in the range of 0.33–1.96%. The polyimides displayed UV-vis absorption maxima and an intense fluorescent intensity in the range of 361–371 and 480–700 nm, respectively.
研究领域:
材料科学
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化学工程
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DOI
高影响因子
EUROPEAN POLYMER JOURNAL
·
2024
·
IF 5.8
Xingwang Lai,Shan Huang,Jialin Zhang,Xialei Lv,Fangfang Niu,Jinhui Li
Photosensitive Solder resist (SR) materials require a high glass transition temperature ( T g > 170 °C) and a coefficient of thermal expansion matching that of copper (CTE≈17 ppm/°C) to meet the demands of manufacturing processes and application reliability. However, the commonly used epoxy resin in SR materials exhibits insufficient mechanical and thermal properties, failing to meet these requirements adequately. To address this issue, alkali-soluble photosensitive poly (amic ester) (PAE) materials were synthesized. By grafting a low-temperature curing accelerator, 6-([1,1′-biphenyl]–4-yl)–4-chloroquinoline (NQL), onto the hydroxyl groups of the PAE, the resultant grafted PAE resin was blended with an alkali-soluble photosensitive modified epoxy resin (APE) to enhance the mechanical and thermal properties of the SR composite. Research indicates that due to the low-temperature curing effect and electrostatic interactions of NQL, SR-2 (with a 10% PAE addition) exhibits a T g of 183 °C and a CTE of 16 ppm/°C, while SR-3 (with a 30% PAE addition) achieves a T g of 204 °C and a CTE of 20 ppm/°C. Furthermore, with the PAE addition of 5%, the lithography quality of SR is enhanced, enabling SR-1 to achieve a pattern resolution of up to 40 μm. The modification method involving PSPI blending has been shown to enhance the thermal stability, dimensional stability, and lithographic performance of SR, indicating significant potential applications in solder resist materials.
研究领域:
材料科学
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电子工程
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产品关联
DOI
高影响因子
POLYMER
·
2020
·
IF 4.231
Haoji Lao,Nafeesa Mushtaq,Guofei Chen,Hongyu Jiang,Yang Jiao,Anjiang Zhang,Xingzhong Fang
Two series of optically transparent polyamide-imides (PAIs) were prepared by copolymerization of trimelletic acid chloride (TMAc), p -phthaloyl chloride (TPC), 2,2′-bis(trifluoromethyl)-[1,1′-biphenyl]-4,4′-diamine (TFDB) and 4,4’-(9-fluorenylidene) diamine (FDA). These series of PAIs displayed high glass transition temperatures ( T g s) ranging from 340 to 441 °C, 5% weight loss temperatures ( T 5% s) in nitrogen with 459–505 °C, and low coefficient of thermal expansion (CTE) of 21–56 ppm/K, which greatly affected by the feed ratio of rigid TPC units and cardo diamine in the polymer main chain. The transmittances at 500 nm (T 500nm ) of the PAI films were found in the range of 70.0–87.7%, All polymers demonstrated good organosolubility and mechanical properties with tensile strengths of 77–146 MPa, tensile moduli of 2.9–5.8 GPa and elongations at break of 2.9–8.2%. PAI-7-8 presented the best combination of high T g of 401 °C and high tensile modulus of 5.0 GPa, low CTE value of 24 ppm/K, and high transparency (T 500nm ) of 87.2%.
研究领域:
聚合物科学
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材料科学
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化学工程
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DOI
高影响因子
Cell Death & Disease
·
2023
·Vol. 14
·期 2
·1-17
·
IF 9
Chen Yulian,Jiang Huanguo,Zhan Zhikun,Lu Jindi,Gu Tanwei,Yu Ping,Liang Weimin,Zhang Xi,Liu Shuwen,Bi Huichang,Zhong Shilong,Tang Lan
Converting lipid disturbances in response to energy oversupply into healthy lipid homeostasis is a promising therapy to alleviate hepatosteatosis. Our clinical studies found that a further elevation of triglyceride (TG) in obese patients with the body mass index (BMI) greater than 28 was accompanied by a further reduction of phosphatidylethanolamine (PE). Shorter survival and poor prognosis were shown for the patients with high TG and low PE levels. Liver X receptor alpha ( LXRα ) knockout mice aggravated high-fat diet (HFD)-induced obesity and lipid disorders, making the TG enrichment and the PE decrease more pronounced according to the liver lipidomics analysis. The RNA-seq from mice liver exhibited that these metabolism disorders were attributed to the decline of Atgl (encoding the TG metabolism enzyme ATGL) and Ept1 (encoding the PE synthesis enzyme EPT1) expression. Mechanistic studies uncovered that LXRα activated the ATGL and EPT1 gene via direct binding to a LXR response element (LXRE) in the promoter. Moreover, both the supplement of PE in statin or fibrate therapy, and the LXRα inducer (oridonin) ameliorated cellular lipid deposition and lipotoxicity. Altogether, restoration of lipid homeostasis of TG and PE via the LXRα-ATGL/EPT1 axis may be a potential approach for the management of hepatosteatosis and metabolic syndrome.
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DOI
PubMed
高影响因子
RSC Advances
·
2018
·Vol. 8
·期 23
·12870-12878
·
IF 2.936
Li Tan,Hailong Li,Mengru Liu
In this study, CMC–LDH beads were prepared and characterized using SEM, FTIR and TG analysis. The beads were applied for the removal of Cr(VI) from aqueous solution. The effects of adsorbent dosage, initial pH and initial concentration of Cr(VI) solution on Cr(VI) uptake were investigated in detail. Moreover, adsorption isotherms and adsorption kinetic models were employed to analyze the adsorption process, and a preliminary study of the reusability of the adsorbent was performed. The experimental results showed that the CMC–LDH beads could remove Cr(VI) from aqueous solution efficiently. When the initial concentration of the Cr(VI) solution was 100 mg L−1 and the adsorbent dosage was 12 g L−1, the removal efficiency of Cr(VI) reached 96.2%. After the CMC–LDH beads were reused 10 times, the removal efficiency of Cr(VI) still remained at 89.6%.
研究领域:
环境科学
·
材料科学
·
化学工程
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产品关联
DOI
PubMed
高影响因子
JOURNAL OF POLYMER SCIENCE
·
2024
·
IF 3.9
Nafeesa Mushtaq,Jinglei Xing,Xiaohong Li,Guofei Chen,Xingzhong Fang
Colorless polyimide (CPI), a heat-resistant polymer being widely used in optoelectrical devices, has attracted worldwide attention. Polyamide-imides due to the incorporation of amide groups into the CPI chains enhance the polymer performance by improving the thermal dimensional stability and excellent mechanical properties without sacrificing the optical transparency. In this article, CPI films PI-(1-3) are synthesized from one-step polymerization of 4,4′-(hexafluoroisopropylidene) diphthalic anhydride (6FDA) and cyclopentanone bis-spironorbornane tetracarboxylic dianhydride (CpODA) with amide-containing diamine N , N ′-(2,2′-bis(trifluoromethyl)-[1,1′-biphenyl]-4,4′-diyl)bis(4-aminobenzamide) (AB-TFDB) and bis(trifluoromethyl)benzidine (TFDB). In comparison, by adjusting the ratio of imide and amide groups in the repeating unit, PI-(4-5) are prepared from copolymerization of terephthaloyl chloride (TPC), 6FDA, and CpODA with TFDB diamine. PI-(1-5) with 90% transmittance in the visible region tailored the excellent thermal and mechanical properties. Particularly, PI-3 exhibited a high glass transition temperature of 412°C, a coefficient of thermal expansion of 20.8 ppm/K, a tensile strength of 128 MPa, and an elastic modulus of 5.4 GPa. The results also concluded that irrespective of the polyamide-imide synthesis strategy, CPI films with similar amide-to-imide ratio in polymer chain demonstrated comparable optical, thermal, and mechanical properties. Graphical
研究领域:
材料科学
·
高分子化学
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DOI
高影响因子
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