Polymer Chemistry
·
2016
·Vol. 7
·期 48
·7427-7435
·
IF 5.687
Nafeesa Mushtaq,Guofei Chen,Lala Rukh Sidra,Yang Liu,Xingzhong Fang
Two novel series of highly organosoluble and curable polyimides containing pendant nitrile groups PI (a–d) and phthalonitrile-terminated polyimides PN-PI (a–d) were prepared by solution polycondensation of isomeric bis(chlorophthalimides)s and 2,6-dichlorobenzonitrile with 4,4′-thiobisbenzenethiol. The inherent viscosities of these copolymers were in the range of 0.37–0.59 dL g−1 in N-methyl-2-pyrrolidone (NMP) at 30 °C. The phthalonitrile and pendant nitrile groups in isomeric poly(thioether-ether-imide)s were thermally crosslinked without a catalyst through thermal curing up to 280–360 °C, which led to the transformation from thermoplastic polymers to thermosetting polymers. All PIs before and after crosslinking were characterised by gel permeation chromatography (GPC), differential scanning calorimetry (DSC) and Fourier transform infrared (FT-IR) spectroscopy. PN-PI (a–d) and PI (a–d) were found to be highly soluble in some solvents, such as chloroform, dimethylacetamide, m-cresol, dimethlyformamide and N-methyl-2-pyrrolidone, while the crosslinked polymers were insoluble in all tested solvents. The crosslinking results of pendant nitrile and terminal phthalonitrile groups are also compared. Both series of PIs showed high thermal stability based on 5% weight loss temperature (T5%) in the range of 471–509 °C and increased up to 35 °C after thermal curing. Polyimides showed high glass transition temperatures (Tgs) ranging from 191–213 °C as determined by DSC, but no detectable Tg was observed after thermal heating, indicating the crosslinked structure of PIs. The mechanical properties also enhanced after the crosslinking of the copolymers. The tensile modulus and strength of the cured PI films were in the range of 3.3–4.7 GPa and 68–122 MPa, respectively, which were up to 62% and 35% higher than the uncured films.
研究领域:
材料科学
·
高分子化学
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产品关联
DOI
高影响因子
JOURNAL OF MEMBRANE SCIENCE
·
2017
·
IF 6.035
Xiaoming Yan,Runlian Deng,Yu Pan,Xiaowei Xu,Issam El Hamouti,Xuehua Ruan,Xuemei Wu,Ce Hao,Gaohong He
Hydroxide exchange membrane fuel cells (HEMFCs) are attracting growing interest owing to their advantages such as low cost and high power density. However, their applications are hindered due to the poor stability of the membrane. Here, we proposed a novel strategy to improve the alkaline stability of hydroxide exchange membranes (HEMs) using the interactions between strongly polar nitrile groups and side-chain functional cations. A poly(ether nitrile) (PEN) was synthesized by the polycondensation of bisphenol A and 2,6-difluorobenzonitrile, and then imidazolium and morpholinium functional groups were integrated by the typical chloromethylation-functionalization method. The existence of the interactions between nitrile groups and cation groups i.e. imidazolium and morpholinium, was proved by the density functional theory calculations. The interactions have two positive effects that contribute to the improvement of the alkaline stability of the PEN based membranes. On the one hand, they increase the LUMO energies of the functional groups; and on the other hand they reduce the free volume around hydrated cationic groups. As a result, PEN based membranes showed much better alkaline stabilities compared to the membrane based on commercial polysulfone that has a similar chemical structure . In addition, given similar swelling ratios, PEN based membranes exhibited higher hydroxide conductivities than simple polysulfone based ones.
研究领域:
化学工程
·
材料科学
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DOI
高影响因子
Polymer Chemistry
·
2024
·Vol. 15
·期 37
·3779-3786
·
IF 4.1
Yin Lu,Jiaqi Wang,Yi Yang,Yichen Jing,Kan Zhang
In this work, a molecular design strategy by incorporating nitrile into ortho-amide benzoxazines was employed for achieving promising high performance thermsosets. We conducted a systematic investigation into the influence of additional nitrile moieties on the properties of ortho-amide benzoxazines. Initially, structural characterization of benzoxazines was performed using NMR and FT-IR spectroscopy, followed by DSC analysis and in situ FT-IR spectroscopy to study the polymerization mechanisms of each benzoxazine monomer. Notably, the thermoset derived from ortho-amide benzoxazine bearing two nitrile groups exhibited exceptional thermal stability (Td5 of 392.5 °C) and high glass transition temperature (Tg of 331 °C), alongside preferable flame retardancy (THR = 3.9 kJ g−1).This approach resulted in a new series of thermosetting resins with low curing temperature and improved comprehensive properties, thereby offering significant potential for the development of advanced thermoset materials with a wide range of intelligent applications.
研究领域:
材料科学
·
高分子化学
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产品关联
DOI
高影响因子
JOURNAL OF POLYMER RESEARCH
·
2019
·Vol. 26
·期 11
·1-8
·
IF 1.53
Tian Yuhan,Pu Zejun,Xia Jialing,Hu Linqing,Cheng Jie,Zhong Jiachun
A novel soluble poly(aryl ether ketone) (PAEK) terminated with 4-nitrophthalonitrile was designed and synthesized, which was used to solve the problem of difficult solution processing. Then, a series of cross-linked PAEK films with different thermal treatment temperatures were fabricated by using 4,4-bis(3,4-dicyanophenoxy)biphenyl (BPH) as a novel cross-linking agent, improving the glass transition temperature ( T g ) of the traditional PAEK. Then, the fourier transform infrared (FT-IR) spectrum, X-ray diffraction (XRD), differential scanning calorimetry (DSC), thermo gravimetric analysis (TGA), dynamic mechanical analysis (DMA), mechanical testing machine and LCR meter were used to investigate the microstructure, thermal, mechanical and dielectric properties of PAEK films, respectively. The results indicated that the increase in heat-treatment time and temperature are beneficial for the improvement of the value of T g and T 5% , and the excellent thermal stability and mechanical properties of PAEK films are demonstrated. Compared to PAEK-1 film, the T g and T 5% both increased by 63 °C for PAEK-4 film. Significantly, the tensile strength of PAEK-3 film (42 MPa) reaches the highest value in comparison with other samples. In addition, the dielectric constants (ε) and loss tangent (tan δ) of PAEK-4 film is as low as 3.67 and 0.001 at 1 kHz, respectively. More importantly, the dielectric properties are found to be relatively stable to near the T g value, which can be widely used for applications in dielectric energy storage at high temperatures.
研究领域:
材料科学
·
高分子化学
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DOI
高影响因子
Materials
·
2024
·Vol. 17
·期 2
·417
·
IF 3.1
Yuehui Wang,Jun Huang,Ye Zhang,Shiwen Zhang,Lili Li,Xuan Pang
In this paper, an environmentally friendly polyacrylonitrile-based (PAN-based) composite membrane with a Janus structure for wastewater treatment was successfully fabricated. To achieve the optimum adsorption of PAN-based Janus composite membrane, the asymmetric wettability was regulated through electrospinning, resulting in TiO2modifying PAN as the hydrophilic substrate layer, and PCL gaining a different thickness as the hydrophobic layer. The prepared Janus composite membrane (PAN/TiO2-PCL20) showed excellent oil/water separation performance for diverse surfactant-stabilized oil-in-water emulsions. For n-hexane-in-water emulsion, the permeate flux and separation efficiency reached 1344 L m−2h−1and 99.52%, respectively. Even after 20 cycles of separation, it still had outstanding reusability and the separation efficiency remained above 99.15%. Meanwhile, the PAN/TiO2-PCL20 also exhibited an excellent photocatalytic activity, and the removal rate for RhB reached 93.2%. In addition, the research revealed that PAN/TiO2-PCL20 possessed good mechanical property and unidirectional water transfer capability. All results indicated that PAN/TiO2-PCL20 with photocatalysis and oil/water separation performance could be used for practical complex wastewater purification.
研究领域:
环境科学
·
材料科学
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产品关联
DOI
PubMed
高影响因子
JOURNAL OF MEMBRANE SCIENCE
·
2013
·
IF 4.093
Xiao-Na Chen,Ling-Shu Wan,Qing-Yun Wu,Suo-Hong Zhi,Zhi-Kang Xu
In this work, we employed CaCO 3 mineralization to greatly improve the water flux and dye rejection of polyacrylonitrile-based (PAN) ultrafiltration membranes. PAN-based membranes were prepared with 1.0–5.0 wt% of poly(acrylic acid) (PAA) as a matrix for mineralization. These membranes were subsequently mineralized with CaCO 3 by an alternate soaking process (ASP). The optimized mineralization condition was 10 cycles of ASP with 100 mM CaCl 2 and Na 2 CO 3 solutions. The resulted membranes were characterized with field emission scanning electron microscopy , X-ray diffraction, and energy dispersion X-ray analysis combined with elemental distribution mapping. The mineralized CaCO 3 particles were found to be deposited throughout the membranes. Results also indicated that the pure water flux of PAN-based membranes decreased with PAA if the content was larger than 1.0 wt%, which was due to the stretching of PAA chains deriving from the electrostatic repulsion of COO − groups. In contrast, the mineralized membranes showed a dramatic increase of water flux owing to the chain collapse of PAA caused by the formation of complexes with Ca 2+ in the mineralization of CaCO 3 as well as the enhanced hydrophilicity by CaCO 3 . The mineralized membranes even showed a high rejection of Congo red, which makes them potential in nanofiltration for dye-polluted wastewater.
研究领域:
材料科学
·
环境工程
✓ 已验证
DOI
高影响因子
Carbon Letters
·
2025
·
IF 5.8
Cao Hongshuo,Tian Yanhong,Sun Jiangman,Zhang Xuejun
Electrochemical treatment has a significant effect on the properties of carbon fibers (CFs). In this study, the effect of mild electric field action on the microstructure and properties of polyacrylonitrile (PAN)-based high-modulus CFs (HMCFs) and high-strength CFs (HSCFs) was investigated. Under the action of a mild electric field, CFs did not show obvious defects, but their microstructure, mechanical properties and electrical properties were affected. For HMCFs, the graphitization degree in both axial and radial directions of the fibers had a decreasing trend, the grain spacing increased, and the grain size and degree of orientation decreased, which led to a decrease in the tensile strength, tensile modulus and axial conductivity. However, for HSCFs, the pattern of change was exactly opposite to that of HMCFs. The results of this study can provide useful guidance for optimizing the production process and surface modification of CFs.
研究领域:
材料科学
·
电化学
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产品关联
DOI
高影响因子
POLYMER
·
2018
·
IF 3.483
Huichao Liu,Qiuhan Luo,Shuo Zhang,Ludi Shi,Jinglong Yang,Ruigang Liu,Mingliang Wang,Caizhen Zhu,Jian Xu
Exploiting new comonomers is still required for high performance polyacrylonitrile (PAN) based carbon fiber. In this paper, we have proposed an efficient methodology, combining of theoretical calculation and experimental verification, to develop new comonomer for polyacrylonitrile (PAN)-based carbon fiber. The cyclization energy barriers of PAN copolymers , including comonomers of α-nitryl acrylic acid (IA-NO 2 ), α-amino acrylic acid (IA-NH 2 ), acrylamide (AAM), itaconic acid (IA), and ethylenesulfonic acid (ESA), have been calculated based on the autocatalytic cyclization mechanism using density functional theory (DFT) at B3LYP/6-31 + G (d, p) level. The theoretical calculation indicated that ionic cyclization of nitrile group was more easily initiated by ESA than other comonomers. Correspondingly, the PAN copolymers including comonomers of ESA and IA have been prepared and studied on their properties. The experimental results further demonstrated the P(AN-co-ESA) copolymer had better thermal properties such as smaller cyclization energy, slower heat release rate, and higher char yielding. Therefore, this theoretical calculation combined with experimental verification methodology is a powerful tool for exploiting new comonomer for PAN-based carbon fiber.
研究领域:
材料科学
·
化学工程
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产品关联
DOI
高影响因子
POLYMER
·
2022
·
IF 4.432
Chong-Jiang Lv,Bin Hao,Akram Yasin,Xiu Yue,Peng-Cheng Ma
Herein, a durable superhydrophobic/superoleophilic membrane with micro-/nano-hierarchical structure was achieved through molecular and structural design of fluorinated polyacrylonitrile-based membrane. In which, the introduction of perfluorooctanol acrylate into copolymer chain and usage of electrospinning/electrospraying technology followed by heat post-treatment provided low surface energy and durable hierarchical structure, respectively. The resultant membrane demonstrated superhydrophobicity and superoleophilicity with water contact angle of 160° and oil contact angle of 0° in air, which endowed the membrane with excellent separation ability for oil/water mixture with separation efficiency above 99% and ultrahigh flux beyond 8000 L/m 2 /h. Furthermore, the obtained membrane maintained its superhydrophobicity after exposure to broad pH, organic solvents , high temperature and ultrasonic treatment, ascribed to the chemical reaction of cyano groups on the surface of fibers and particles during the heat post-treatment. This work provides a promising strategy to fabricate superwetting membrane to remove trace amount of water in oil.
研究领域:
材料科学
·
环境工程
✓ 已验证
产品关联
DOI
高影响因子
Nanoscale
·
2020
·Vol. 12
·期 32
·16934-16943
·
IF 6.895
Chenshuo Wu,Hongpeng He,Yahui Song,Cuixia Bi,Lixiang Xing,Wei Du,Shenggang Li,Haibing Xia
In this work, uniform and large gold nanoparticles (Au NPs) including quasi-spherical (QS) Au NPs with average diameters of 70 to 196 nm and trisoctahedral (TOH) Au NPs with average diameters of 140 to 195 nm were successfully synthesized by controlling the concentration of Cu2+ ions and the particle number of 3 nm Au-NP seeds, respectively, using a one-step seeded growth method with Cu2+-mediated Ostwald ripening. It is found that because of the concentration-dependent under-potential deposition of Cu2+ ions (CuUPD), 3 nm Au-NP seeds are firstly changed into Au NPs with a controlled QS- or TOH shape at the initial growth stage, followed by the conformal growth of Au atoms onto the initially formed Au NPs due to Cu2+-mediated Ostwald ripening, in which the extra Au atoms come from the dissolution of in situ Au nuclei by the unavoidable self-nucleation. Moreover, the as-prepared QS Au NPs with a rough surface exhibit a better SERS performance for physically adsorbed probes (crystal violet, CV) than the TOH Au NPs with sharp tips and with a comparable size. Furthermore, the as-prepared QS Au NPs can be used to distinguish nitrile and isonitrile groups by surface-enhanced Raman scattering (SERS) due to the presence of deformation twinnings. Thus, the as-prepared QS Au NPs with a rough surface and deformation twinnings can be further used as templates for the fabrication of bimetallic materials with multi-functionalities.
研究领域:
纳米材料
·
材料科学
·
分析化学
·
表面科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
IONICS
·
2017
·Vol. 24
·期 1
·285-296
·
IF 2.062
Jiao Wenqiang,Fan Yujiao,Huang Chengde,Sanglin
Modified micron-sized commercial polyacrylonitrile-based carbon fiber (PAN-CF) electrodes were prepared using an electrochemical method. Such modified electrodes exhibit remarkably improved catalytic activity together with outstanding stability for oxygen reduction reactions (ORR) in seawater batteries. The effects of three solutions, including sodium hydroxide, sulfuric acid, and sodium nitrate, on the electrode electrochemical behavior were investigated and compared. The results show that the dual actions of the surface N and O functional groups will simultaneously improve the hydrophilic properties and catalytic activity of the electrode. In addition, we observed that the pyridine nitrogen- or/and pyridone-related active sites are prone to catalyzing the electrode process.
研究领域:
材料科学
·
电化学
✓ 已验证
DOI
高影响因子
COMPOSITES SCIENCE AND TECHNOLOGY
·
2020
·
IF 7.094
Hongji Chen,Jianxiao Yang,Qin Shuai,Jun Li,Qin Ouyang,Shu Zhang
The high modulus PAN-based carbon fibers (CFs) were prepared using the B 4 C-doped PAN as a precursor which was synthesized by in-situ polymerization of acrylonitrile monomer with B 4 C nanoparticles , and were characterized to investigate the effects of B 4 C nanoparticles on stabilization and carbonization behaviors of the as-spun fibers and to compare the structural properties of the B 4 C-doped CFs (B-CF) with the pristine CFs (P-CF). The results showed that the B-CF-1000 prepared at carbonization temperature of 1000 °C had lower tensile strength than P–CF–1000 due to the defects and disordered structures in the B-CF-1000 caused by the doped B 4 C, while the B-CF-3000 prepared at graphitization temperature of 3000 °C had much higher tensile modulus of 399 GPa than P–CF–3000 of 251 GPa under the effect of boron catalytic graphitization. Moreover, the skin-core structure of B-CF had significantly improved compared to P-CF, which was caused by the fact that B 4 C inhibited the oxidation reaction and limited the shrinkage of the fibers during stabilization so as to benefit the entry of oxygen into the fiber core. The above results indicated that the in-situ doped B 4 C does play a significant role in catalytic graphitization and improving microstructure of PAN-based CFs.
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
危险品化学品经营许可证（带存储）