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红外光谱原位跟踪活性自由基聚合反应过程研究 总被引:1,自引:0,他引:1
使用新型可插入式红外光谱仪原位检测在4-羟基2,2,6,6-四甲基氧化哌啶醇(HTEMPO)存在下苯乙烯稳定自由基活性均聚合反应和苯乙烯/甲基丙烯酸羟丙酯的共聚合反应以及苯乙烯原子转移活性自由基聚合(ATRP)反应三个过程,分别考虑了它们的反应动力学,并给出了可能的聚合反应机理。研究结果表明,对于均相的苯乙烯(St)均聚合反应和苯乙烯(St)/甲基丙烯酸羟丙酯(HPMA)的自由基共聚合反应体系,聚合反应显示一定的诱导期,与反应体系中存在的HTEMPO捕捉自由基有关,而对于St/HPMA共聚合体系,诱导期更长,这是因为HPMA易和HTEMPO自由基发生氢转移反应,导致游离的HTEMPO浓度升高。最后用红外光谱实时跟踪苯乙烯非均相ATRP过程,发现苯乙烯聚合反应动力学接近于表现零级。因为单体分子在由增长自由基、卤化铜和联二吡啶形成的络合物的界面增长,与单体相内St浓度无关。 相似文献
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通过带有PEG官能团的双丙烯酸酯大分子单体的RAFT环聚合反应合成含有十一元环重复结构的PEG大分子刷.不同PEG长度的连接1,2,3-三氮唑的双丙烯酸酯大分子单体通过点击化学反应合成.PEG侧链的较大位阻效应影响双丙烯酸酯大分子单体的聚合行为,以致于双丙烯酸酯大分子单体优先进行环化聚合反应而不发生交联反应.核磁数据和凝胶渗透色谱证明高效的环化聚合反应,而且没有副反应发生.PEG大分子刷在紫外光激发下有较强的荧光,而荧光则强烈依赖于聚合物刷的浓度,这归因于环聚合物在水中的聚集.PEG大分子刷的荧光能被DNA淬灭. 相似文献
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针对混合浮游藻类群落离散三维荧光光谱特征识别,对比分析了简单卷积神经网络(PlainCNN)和文本卷积神经网络(TextCNN)模型对5种常见门类藻(铜绿微囊藻、斜生栅藻、菱形藻、楯形多甲藻和隐藻)混合数据的种类识别准确率及浓度测量精度。结果表明,在藻类独立识别及浓度回归分析中,PlainCNN模型对测试集的平均识别准确率和浓度输出结果的平均均方误差分别为90%和0.052,均优于TextCNN模型。为了同时实现混合藻类种类识别和浓度分析,基于PlainCNN模型提出了多任务卷积神经网络PlainCNN-MT模型。该模型对混合藻类种类识别的平均准确率提高至95%,浓度输出结果的平均均方误差降低至0.039,表明多任务卷积神经网络在浮游藻类群落识别与定量分析中更具优势。 相似文献
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介绍了一种基于支持向量机的混合气体红外光谱组分浓度和种类分析的新方法.利用核函数将组分气体特征吸收谱线重叠严重的混合气体光谱在高维空间变换后,建立SVM回归校正模型,进行混合气体浓度分析.在利用支持向量机回归校正模型进行混合气体组分浓度分析的同时,证明支持向量机回归校正模型也可用于混合气体组分种类分析.对不同组分和不同组分浓度的混合气体红外光谱数据进行了实验,研究了谱仪扫描间隔、分析特征波长范围、核函数和惩罚因子等因素对分析结果的影响.混合气体组分浓度实验结果的最大平均绝对误差Mean AE为0.132%;混合气体组分种类识别的准确率大于94%.解决了传统的光谱分析方法中光谱特征谱线重叠、光谱数据的维数大、定性和定量分析无法使用同一方法等问题,可用于其他混合气体的红外光谱分析,具有实际应用价值. 相似文献
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丙烯酰胺在反向微乳液中聚合反应的研究 总被引:4,自引:0,他引:4
在水-AOT-甲苯反向微乳液体系中,选用了四种引发剂AIBN,(NH4)2S2O3,NaHSO3,MnSO4-O2-NaHSO3,开展丙烯酰胺的聚合反应的研究,其中着重研究引发剂的浓度,反应温度等因素对聚合分子量的影响。 相似文献
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采用溶胶-凝胶法制备出一系列不同催化剂种类和浓度的三聚氰胺-甲醛(MF)有机气凝胶模板,通过傅里叶变换红外光谱仪、热分析仪、N2吸附等测试手段对其分子结构、热稳定性、孔结构进行了表征。测试结果表明:催化剂种类和浓度变化不影响模板的分子结构和热性能;各模板热解程度均达97%;相比NaOH和NaHCO3为催化剂制备的模板,Na2CO3为催化剂时,制备的模板更优,比表面积和孔容较大,孔分布范围较宽; 当三聚氰胺与催化剂的浓度比为500时,比表面积达到最大。 相似文献
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紫外光引发合成阴离子聚丙烯酰胺及其表征 总被引:1,自引:0,他引:1
选择了三种单体:丙烯酰胺(AM)、2-丙烯酰胺基-2-甲基丙磺酸(AMPS)和丙烯酸(AA),在复合引发剂的作用下,紫外光照射共聚得到阴离子聚丙烯酰胺(APAM)。研究了单体配比、单体总质量分数以及引发剂浓度等因素对聚合反应的影响,以产物特性粘度为目标进行了制备条件的优化,并对聚合产物的紫外、红外、电镜等结构和热性能进行表征。结果表明,在单体配比为70∶10∶10、单体质量分数为40%、引发剂浓度0.20%、反应体系pH值为9.0以及光照60min条件下,能够制得特性粘度为1.6×103 mL.g-1的阴离子聚丙烯酰胺。 相似文献
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Bacterial cellulose/polyaniline nanocomposite film was prepared by the chemical oxidative polymerization of aniline with bacterial cellulose. Polyaniline conducting polymer nanocomposite films with bacterial cellulose fibers was prepared and characterized. In nanocomposite film, the bacterial cellulose was fully encapsulated with polyaniline by direct polymerization of the respective monomers using the oxidant and dopant. These bacterial cellulose/polyaniline nanocomposite films materials exhibited the inherent properties of both components. The deposition of a polyaniline on the bacterial cellulose surface was characterized by SEM. XPS revealed a higher doping level of the nanocomposite films doped with p-TSA dopant. From the cyclic voltammetry results, the polyaniline polymer was thermodynamically stable because redox peaks of electrochemical transitions in the voltagrams were maintained in bacterial cellulose/polyaniline nanocomposite films. 相似文献
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Qiang Zhang Fangjun Liu Liang Li Guoliang Pan Songmin Shang 《Journal of nanoparticle research》2011,13(1):415-421
A simple strategy for the one-step synthesis of polyaniline/AgCl nanocomposites at the water/magnetic ionic liquid interface was reported. By controlling the reactive conditions, highly dispersed polyaniline/AgCl nanocomposites with their size ranging around 50–80 nm were obtained with magnetic ionic liquid as the oxidant. Transmission electron microscopy was used to show the morphology of the nanocomposites. The nanocomposites were also characterized by Fourier transform infrared spectroscopy, X-ray diffraction, and thermogravimetric analysis. Moreover, polyaniline/AgCl nanocomposites on a glassy carbon electrode showed strong electrocatalytic activity for H2O2 and could be used to construct a H2O2 biosensor. 相似文献
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Qiang Zhang Fangjun Liu Liang Li Guoliang Pan Songmin Shang 《Journal of nanoparticle research》2011,13(1):423-421
A simple strategy for the one-step synthesis of polyaniline/AgCl nanocomposites at the water/magnetic ionic liquid interface
was reported. By controlling the reactive conditions, highly dispersed polyaniline/AgCl nanocomposites with their size ranging
around 50–80 nm were obtained with magnetic ionic liquid as the oxidant. Transmission electron microscopy was used to show
the morphology of the nanocomposites. The nanocomposites were also characterized by Fourier transform infrared spectroscopy,
X-ray diffraction, and thermogravimetric analysis. Moreover, polyaniline/AgCl nanocomposites on a glassy carbon electrode
showed strong electrocatalytic activity for H2O2 and could be used to construct a H2O2 biosensor. 相似文献
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Two kinds of prickly polyaniline samples, prickly polyaniline nanorods and microgranules, are prepared through the chemically oxidative polymerization method by regulating the concentration of aniline. Scanning electron microscopy images indicate that the diameter of prickly polyaniline nanorods (PPNRs) is about 80 nm and the size of prickly polyaniline microgranules (PPMGs) is about 400 nm. The as-prepared prickly polyaniline samples are subsequently explored as the Pt-free counter electrode materials for dye-sensitized solar cells (DSCs). Electrochemical impedance spectroscopy and cyclic voltammetry measurements demonstrate that PPNR electrode displays superior electrocatalytic activity for the I3 ? reduction reaction to PPMG electrode, which can be attributed to the unique prickly nanorod structure that provides abundant electrocatalytic active sites and the fast charge transport pathway simultaneously. As a consequence, the DSC fabricated with PPNR counter electrode achieves a high conversion efficiency of 6.86% under illumination of 100 mW cm?2, which is close to the efficiency of a Pt electrode-based device. This work presents a promising way to develop Pt-free and high-efficiency counter electrode in DSCs. 相似文献
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《Current Applied Physics》2007,7(1):68-75
In the present paper, we have reported the chemical synthesis and characterization of polyaniline doped with tellurium. The aniline was polymerized by chemical oxidation using ammonium persulphate as an oxidant and was doped with different concentrations of tellurium. Doped PANI was characterized by using FTIR, DSC and two-probe conductivity measurement. The dc conductivity has been measured to see the effect of tellurium and its mechanism has been explained by the formation of polarons and bipolarons that move along the polymer chain, and gives rise to the electrical conductivity. The observed increase in conductivity of polyaniline is attributed due to the incorporation of Te into the PANI chain. Glass transition temperature (Tg) and enthalpy (ΔH) have been calculated from DSC measurements. FTIR spectra suggest the structural changes after incorporation of Te in polymeric chain. 相似文献
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Kaushik Mallick Michael Witcomb Rudolph Erasmus André Strydom 《Journal of Macromolecular Science: Physics》2013,52(1):134-141
Paramagnetism in polyaniline can be generated during synthesis if cerium (IV) ammonium nitrate (CAN) is used as a polymerizing (oxidizing) agent. During the reaction, in situ formation of Ce3+ ions are doped in the spherical polyaniline particles and show paramagnetic behavior throughout the experimental temperature range (400–1.9 K). The result indicated that the Ce3+ ions covalently functionalized with the chain nitrogen of the polyaniline. 相似文献
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以油溶性过氧化羟基异丙苯(CHP)为氧化剂,Al2O3为催化剂,引入超声作用,以正辛烷为模拟油品对油中二苯并噻吩的氧化进行了研究。考察了反应温度、反应时间、催化剂用量、氧硫比、超声功率对二苯并噻吩(DBT)降解率的影响并进行了正交实验,结果表明,各因素影响程度大小依次为:反应温度>催化剂用量>超声功率>反应时间>氧硫比,在反应温度为70℃,反应时间为45 min,氧硫比为5:1,催化剂用量为0.3 g,超声功率为60 W的最佳氧化条件下,DBT的降解率达到了88.0%。 相似文献
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《Composite Interfaces》2013,20(7):411-424
Response surface methodology was used to simultaneously optimize the electrical and mechanical properties of newly developed conducting biofibers made up of kenaf fiber/polyaniline (KF/PANI). The effect of process parameters such as PANI amount (1–10 wt.%), dopant concentration (5–25 N), and molar ratio of aniline/oxidant solutions (0.5–1.5) were studied using Design of Experiment. Both of the responses (electrical conductivity and unit break) obtained a quadratic model. The experimental values were in good agreement compared to the optimized process. The scanning electron microscope images of the optimized sample revealed uniform PANI component on the KF with nanofibrillar features. 相似文献
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Claudio H. B. Silva Daniela C. Ferreira Vera R. L. Constantino Marcia L. A. Temperini 《Journal of Raman spectroscopy : JRS》2011,42(8):1653-1659
The pH–structure correlation of the products of aniline peroxydisulfate reaction was mainly investigated by resonance Raman spectroscopy. The reactions of aniline and ammonium peroxydisulfate were carried out in aqueous solutions of initial pH ranging from 4.9 to 13.2 and monomer/oxidant molar ratio of 4/1. For an initial pH of 4.9, the spectroscopic techniques showed that the emeraldine salt form of polyaniline (PANI–ES) is the main product, corroborating that the usual head‐to‐tail coupling mechanism is taking place. The resonance Raman spectra at 1064 nm exciting wavelength were useful to detect the emeraldine salt as a minor product for reactions at an initial pH of 5.3–11.5. The Raman spectra of the main product of the reaction at initial pH of 13.2 excited at 1064 and 413.1 nm showed new spectral features consistent with 1,4‐Michael‐type adducts of aniline monomers and 1,4‐benzoquinone‐monoimine unit. These compounds and their products of hydrolysis/oxidation are the predominant species for the reaction media of initial pH from 5.3 to 13.2. In order to get PANI with different nanoscale morphologies, a pH value of more than 0 or 1 was used in the aniline polymerization. The spectroscopic data obtained in this work reveal that head‐to‐tail coupling does not occur when aniline reacts at media pH higher than about 5. It is suggested that chemical structures of the products of aniline oxidation by an unusual mechanism are the driving force for the development of assorted morphologies. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
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Guohui Chang Yonglan Luo Fang Liao Wenbo Lu Xuping Sun 《Journal of nanoparticle research》2011,13(2):471-477