Polymer Chemistry
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2015
·Vol. 6
·期 20
·3747-3753
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IF 5.52
Bo Zhao,Yaochen Zheng,Zhulin Weng,Shengying Cai,Chao Gao
This paper firstly revealed the electrophilic effect of thiol groups on thiol–yne polymerization. For this, we designed and synthesized five kinds of α-thiol-ω-alkynyl AB2 type intermediates with thiols with different electrophilicities. The thiol electrophilic effect can be assessed by chemical shift (δ) and measured directly by nuclear magnetic resonance (NMR) spectroscopy. As the evidence from gel permeation chromatography (GPC) and NMR tracking measurements shows, the polymerization rate and molecular weight (MW) were significantly enhanced as the thiol electrophilic effect reduced. On the contrary, with increasing electrophilicity of the thiol, the resultant degrees of branching (DBs) increased. The semiquantitative relation between reactive rate constant (k) and δ (or electrophilicity of thiol) can be expressed by k = 2.41–1.34δ. Therefore, important features of thiol–yne polymerization and HPTEs, such as rate constant (k), MW, DB, etc., can be roughly estimated in advance by the NMR measurement of the thiol's electrophilic effect.
研究领域:
材料科学
·
化学
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高影响因子
JOURNAL OF ALLOYS AND COMPOUNDS
·
2021
·
IF 5.316
Yi Peng,Juntao Wang,Ying Yan,Wenlei Wang,Hongbo Xiao
In this work, a high content of pyrrole nitrogen carbon nitride (HPCN)-SnS 2 has been successfully constructed with −C═Sn− chemical bond as the interface framework. The charge state of Sn species was adjusted by β particles to obtain controllable sulfur defects onto the HPCN-SnS 2 through electron beam irradiation (EBI). The composites exhibited excellent photocatalytic oxidation capacity of As(Ⅲ) and adsorption capacity of As(Ⅴ). It is confirmed that the optimized HPCN-SnS 1.38 can remove the total As concentrations below 0.40 mg/L within 80 min. Additionally, the effect of various conditions (pH value and type of anions) was evaluated using degradation experiments, and HPCN-SnS 1.38 could be reused at least 5 times without an obvious reduction in the photocatalysis and adsorption performances. Based on the experimental results, the photocatalytic mechanism of As(Ⅲ) by HPCN-SnS 2 after electron beam irradiation was studied. Free radical quenching experiments and electron paramagnetic resonance (EPR) showed that the oxidation of As(III) under visible light is mainly controlled by •O 2 − and •OH, and •OH is converted from •O 2 − under acidic conditions.
研究领域:
环境科学
·
材料科学
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DOI
高影响因子
Energy Storage Materials
·
2020
·
IF 16.28
Mi Tang,Cheng Jiang,Shiyuan Liu,Xiang Li,Yuan Chen,Yanchao Wu,Jing Ma,Chengliang Wang
Various alternatives of Li-ion batteries (LIBs) have been developed due to the scarcity of Li resources and growing demand of LIBs. However, most of these candidates are suffering the challenges of sluggish intercalations of large-sized ions (e.g. Na + , K + or anions etc.), leading to low capacity, poor cycleability and particularly performance decay at high rate. Herein, we report the precise synthesis of a novel conjugated polymer (polypyrene sulfide, PPYS) and its application in storage of anions. Furthermore, we propose a novel concept that the electropositive covalent organic frameworks (COFs) could be able to adsorb anions by electrostatic attractions and thereby facilitate the transport of anions. This novel concept for enhancing the intercalation kinetics of large-sized anions is demonstrated by using the PPYS cathodes as proof-of-concept. After addition of small amount COFs, the capacity, the rate capability and the cycleability of PPYS are improved impressively. Such strategy can be expected to be universal to other redox polymers and may be also applicable to enhance the transport of other large-sized ions in multifunctional applications. These results will also extend the application fields of COFs.
研究领域:
材料科学
·
电化学
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高影响因子
POLYMER DEGRADATION AND STABILITY
·
2021
·
IF 5.03
Zishuai Wang,Yaoqiang Wang,Shengnan Xu,Yu Jin,Zequn Tang,Gang Xiao,Haijia Su
Glycolysis of poly (ethylene terephthalate) (PET) is a promising way to recycle waste PET and produce bis-(2-hydroxyl ethyl) terephthalate (BHET), the monomer of PET. However, traditional catalysts will cause environment pollution and economic burden. In this work, based on the green and low-cost graphitic carbon nitride colloid, we developed a pseudo-homogeneous system for PET glycolysis, and poly (bisphenol A carbonate) (BPA-PC) and polylactic acid (PLA) methanolysis. Using this system, 100% conversion of PET and 80.30% yield of BHET were achieved, and the reaction time was 2-8 times shorter than that of other metal-based catalysis systems. Catalyst and ethylene glycol were reused five times directly preserving their activity. Furthermore, the degradation of real commercial plastics has also been achieved. According to FT-IR, XPS, and 1 H NMR characterization results, the nucleophilic attack ability of ethylene glycol and electrophilicity of the PET carbonyl's carbon are enhanced by the formation of hydrogen bond between ethylene glycol, PET and catalyst.
研究领域:
材料科学
·
化学工程
·
环境科学
·
催化
·
高分子化学
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回收技术
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DOI
高影响因子
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