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51.
Eléonore Mathis Marie-Laure Michon Claude Billaud Pauline Grau Anthony Bocahut Caroll Vergelati Didier R. Long 《Journal of polymer science. Part A, Polymer chemistry》2020,58(8):1177-1188
Thermoset (TS) epoxy resins can be toughened with a thermoplastic (TP) for high-performance applications. The final structure morphology has to be controlled to achieve high mechanical properties and high impact resistance. Four polyethersulfone-modified epoxy resins are considered. They consist of different epoxy monomer structure (TGAP, triglycidyl-p-aminophenol and TGDDM, tetraglycidyl diaminodiphenylmethane) and a fixed amount of thermoplastic, and they are cured with two different amounts of curing agent. A reaction-induced phase separation occurs for all formulations generating morphologies, different in shapes and scales. The aim is to control the final morphology and in particular its dominant length scale. This morphology depends on the phase separation process, from the initiation to its final stage. The initiation relies on the relative miscibility of the components and on the stoichiometry between epoxy and curing agent. The kinetics depends on the viscosity of the systems. The different morphologies are characterized by electron microscopy or neutron scattering. Dynamic mechanical analysis allows confirming the presence of a phase separation even when it is not observable by electron microscopy. Vermicular morphologies with few hundreds nanometer width are obtained for the systems containing the TGAP as epoxy monomer. Systems formulated with TGDDM presents morphologies on much smaller scale of order a few tens of nanometers. We interpret the different sizes of the morphologies as a consequence of a larger viscosity for the TGDDM systems as compared to the TGAP ones rather than by a latter initiation of phase separation. 相似文献
52.
Morgan A. Higgins Christopher R. Maroon Jacob Townsend Xinyi Wang Konstantinos D. Vogiatzis Brian K. Long 《Journal of polymer science. Part A, Polymer chemistry》2020,58(18):2644-2653
Polymeric membranes have shown tremendous promise for the separation of CO2 from flue gas streams. However, few systematic studies have been conducted to better understand the impact that chemical functionalities have on membrane-based gas separation performance. To address this gap, we herein describe the synthesis and gas separation performance of a series of vinyl-addition polynorbornenes bearing various CO2-philic functional groups. To facilitate direct comparison between functional groups, each material was designed to maintain a common polymer backbone. Though the incorporation of CO2-philic moieties within a dense polymeric membrane is frequently hypothesized to enhance CO2 solubility, and thereby increase CO2/N2 selectivity, our results demonstrate that the incorporation of CO2-philic groups onto a common polymer backbone do not necessarily result in increased gas separation performance. Experimental and computational results demonstrate that the incorporation of amidoxime groups onto a polynorbornene backbone increase CO2/N2 selectivity, whereas commonly employed ethereal side chains only increased permeability. 相似文献
53.
Dr. Gijs M. ter Huurne Dr. Pongphak Chidchob Dr. Augustin Long Prof. Alexandre Martinez Prof. Anja R. A. Palmans Dr. Ghislaine Vantomme 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(44):9964-9970
The design and the characterization of supramolecular additives to control the chain length of benzene-1,3,5-tricarboxamide (BTA) cooperative supramolecular polymers under thermodynamic equilibrium is unraveled. These additives act as chain cappers of supramolecular polymers and feature one face as reactive as the BTA discotic to interact strongly with the polymer end, whereas the other face is nonreactive and therefore impedes further polymerization. Such a design requires fine tuning of the conformational preorganization of the amides and the steric hindrance of the motif. The chain cappers studied are monotopic derivatives of BTA, modified by partial N-methylation of the amides or by positioning of a bulky cyclotriveratrylene cage on one face of the BTA unit. This study not only clarifies the interplay between structural variations and supramolecular interactions, but it also highlights the necessity to combine orthogonal characterization methods, spectroscopy and light scattering, to elucidate the structures and compositions of supramolecular systems. 相似文献
54.
Numerical Algorithms - This paper presents a class of low memory quasi-Newton methods with standard backtracking line search for large-scale unconstrained minimization. The methods are derived by... 相似文献
55.
Nonlinear Dynamics - Based on the non-planar vibration equations of a cable made of carbon fiber reinforced polymer (CFRP), the nonlinear behaviors of the cable are studied. The one-to-one internal... 相似文献
56.
Hongjin Wang Tengfei Long Hao Zhang Meng Li Qi Sun Xin Zhai Lixin Sun 《Biomedical chromatography : BMC》2022,36(4):e5301
3,4-Difluorobenzyl(1-ethyl-5-(4-((4-hydroxypiperidin-1-yl)-methyl)thiazol-2-yl)-1H-indol-3-yl)carbamate (NAI59), a small molecule with outstanding therapeutic effectiveness to anti-pulmonary fibrosis, was developed as an autotaxin inhibitor candidate compound. To evaluate the pharmacokinetics and plasma protein binding of NAI59, a UPLC–MS/MS method was developed to quantify NAI59 in plasma and phosphate-buffered saline. The calibration curve linearity ranged from 9.95 to 1990.00 ng/mL in plasma. The accuracy was −6.8 to 5.9%, and the intra- and inter-day precision was within 15%. The matrix effect and recovery, as well as dilution integrity, were within the criteria. The chromatographic and mass spectrometric conditions were also feasible to determine phosphate-buffered saline samples, and it has been proved that this method exhibits good precision and accuracy in the range of 9.95–497.50 ng/mL in phosphate-buffered saline. This study is the first to determine the pharmacokinetics, absolute bioavailability, and plasma protein binding of NAI59 in rats using this established method. Therefore, the pharmacokinetic profiles of NAI59 showed a dose-dependent relationship after oral administration, and the absolute bioavailability in rats was 6.3%. In addition, the results of protein binding showed that the combining capacity of NAI59 with plasma protein attained 90% and increased with the increase in drug concentration. 相似文献
57.
Long Jiao Yanna Zhang Zhijun Du Xuemin Dai Hanfu Wang Zhixin Dong Haibo Yao Xuepeng Qiu 《Journal of polymer science. Part A, Polymer chemistry》2022,60(16):2454-2464
To tolerate high processing temperature during the fabrication of low-temperature polycrystalline silicon thin-film transistors (LTPS–TFT) in flexible OLED devices, the polyimide (PI) films, which are used as substrate, should have ultra-high glass transition temperature (Tg > 450°C) and ultra-low coefficient of thermal expansion (CTE at 0–5 ppm K−1). In this paper, two novel heterocyclic monomers, namely, N,N'-(xanthone-2,7-diyl)bis(4-aminobenzamide) (p-DAXBA) and N,N'-(xanthone-2,7-diyl)bis(3-aminobenzamide) (m-DAXBA), which contain a xanthone moiety, are prepared and polycondensed with pyromellitic dianhydride (PMDA), respectively. PI films (PIa and PIb) with intrinsic high Tg and low CTE are designed from the perspective of rigid conjugate xanthone structure and hydrogen bonding interaction. It is found that the PIa films prepared by p-DAXBA have better linear structure of molecular chains and show relatively higher Tg and lower CTE. The Tg of PIa-40 is greater than 450°C, and CTE can reach as low as 2.7 ppm K−1, tensile strength of 179 MPa, modulus of 5.67 GPa, indicating potential application prospect as a flexible OLED substrate. 相似文献
58.
Xiaotong Fan Dr. Kai Huang Prof. Long Chen Haipeng You Menglei Yao Prof. Hao Jiang Prof. Ling Zhang Prof. Cheng Lian Dr. Xiangwen Gao Prof. Chunzhong Li 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2023,135(2):e202215342
Supercapacitor represents an important electrical energy storage technology with high-power performance and superior cyclability. However, currently commercialized supercapacitors still suffer limited energy densities. Here we report an unprecedentedly respiring supercapacitor with chlorine gas iteratively re-inspires in porous carbon materials, that improves the energy density by orders of magnitude. Both electrochemical results and theoretical calculations show that porous carbon with pore size around 3 nm delivers the best chlorine evolution and adsorption performance. The respiring supercapacitor with multi-wall carbon nanotube as the cathode and NaTi2(PO4)3 as the anode can store specific energy of 33 Wh kg−1 with negligible capacity loss over 30 000 cycles. The energy density can be further improved to 53 Wh kg−1 by replacing NaTi2(PO4)3 with zinc anode. Furthermore, thanks to the extraordinary reaction kinetics of chlorine gas, this respiring supercapacitor performs an extremely high-power density of 50 000 W kg−1. 相似文献
59.
结合大学化学的教学现状,针对学生的需求,深入思考在教学过程中设置习题课的重要性和相关问题。从教师素质、班级规模、教学方法、习题构建与讲解以及考试等不同角度提出有效提高习题课效率的策略。进一步探讨线上线下混合式习题课教学模式的可行性,并提供可参考的教学案例,以期促进大学化学专业课程的教与学。 相似文献
60.