气体膨胀液体的热力学性质研究及其在碳纳米管功能化修饰中的应用

Gas Expanded Liquids: Thermodynamic Property Investigation and Application in MWNTs’ Functionalization

作者: 专业:物理化学 导师:李宏平 年度:2010 学位:硕士  院校: 郑州大学

Keywords

gas expanded liquids (GXLs), ethyl acetoacetate, tautomerism-equilibrium, poly-4-vinylpyridine, multi-walled carbon nanotubes

        如今,大量溶剂的使用,给人类带来了沉重的环境和经济负担,寻找一种新的绿色溶剂是解决这一问题的一个途径。气体膨胀液体(GXLs)是最近几年来才在超临界流体基础之上发展起来的新型绿色介质,它的研究和应用具有十分重要的理论意义和实际价值,而了解气体膨胀液体复杂多样的性质以及如何让它为人们所利用仍是我们要解决的难题。据此,本论文主要围绕GXLs的溶剂性质及其GXLs作为介质在碳纳米管的功能化修饰方面的应用,进行了以下二个方面的工作,内容提要如下:GXLs的溶剂性质研究:在298.15K及313.15K下,沿着体系汽-液平衡的泡点线,测定了气体膨胀液体(C02+甲醇)在不同压力下的体积膨胀系数,用紫外分光光度计测定了乙酰乙酸乙酯(EAA)在气体膨胀液体(CO2+甲醇)中的异构化平衡,计算了CO2+甲醇中EAA的异构化平衡常数(Kc),研究了EAA的异构化平衡常数随压力及温度的变化规律。同时,根据所得平衡常数的结果分析了气体膨胀液体的溶剂性质变化规律。结果如下:(1)CO2+甲醇的体积膨胀系数(α)随压力增大而增大,低压时α变化不明显,高压时急剧变化;(2)Kc随体积膨胀系数(α)的增大而增大,α较小时Kc随之变化不明显,较大时Kc急剧增大;(3)由Kc的变化趋势可分析出,CO2+甲醇混合体系的极性随CO2含量的增大而逐渐减弱。GXLs作为介质在碳纳米管的聚合物功能化修饰方面的应用:我们利用氮氧稳定自由基聚合法合成了一系列不同分子量(2169,17290,29900)的聚4-乙烯基吡啶(P4VP),然后将聚4-乙烯基吡啶与多壁碳纳米管(MWNT)充分混合后,置于CO2/DMF的气体膨胀液体(GXLs)中,根据CO2-DMF混合流体的气液平衡数据,我们考察了125℃等温条件下,GXLs中CO2压力的变化,对碳纳米管上的聚合物接枝率的影响。拉曼光谱、热重和透射电镜的分析显示:(1)我们成功地在GXLs中实现了P4VP对多壁碳纳米管的功能化修饰,修饰后的MWNT既可分散于有机溶剂中(eg:二氯苯、DMSO)又可分散于酸性的水溶液中;(2)与在常规条件下相比,在GXLs中的优势更为明显,我们不仅可以大大减少有机溶剂的用量,而且还可以通过便捷地调节GXLs的压力,实现多壁碳纳米管上的聚合物接枝率的可控,最终实现MWNT的功能可控。
    Solvent usage has been linked to waste generation and associated with environmental and economic burdens. To find a new green solvent is one of the solutions to solve our problem. Gas expanded liquids (GXLs) is a new and green media whose development is based on supercritical fluids in recent years. The research and applications of GXLs have great theoretical and practical value. To understand the versatile properties of GXLs and explore its potential applications is still a critical problem we have to face. Accordingly, the work in my thesis is described in the following two parts:the solvent property investigation of GXLs and its potential applications in MWNT functionalization as shown below:Part one:Tautomerism equilibrium of ethyl acetoacetate (EAA) in gas-expanded liquids (CO2+methanol) was measured by UV-Vis spectroscopy at 298.15K (or 313.15K) with pressures along the bubble point curve of the corresponding CO2+methanol phase diagram. The volume expansion coefficient (a) of the gas-expanded liquids was also determined at different pressures along the bubble point curve of the vapor-liquid equilibrium at 313.15K and 298.15K, respectively The equilibrium constant (Kc) of EAA in the binary mixtures was calculated, and the dependence of Kc as a function of pressure and temperature was also studied. The results are shown as follows:Firstly, it’s found that the volume expansion coefficient is rising with the increasing pressure. The change in volume expansion coefficient isn’t obvious at low pressures but dramatical at high pressures.Secondly, the pressure dependence of Kc in GXLs:Kc at 298.15K does not change significantly within low pressure range. However, Kc increases rapidly at high pressures when pressure is greater than 4.5 MPa. The similar trend is also observed at 313.15 K.Thirdly, through the pressure dependence of Kc, it is found that the polarity of CO2+methanol mixtures gradually decreases with increasing CO2 mole fraction.Part two:The free radical polymerization of poly-4-vinylpyridine(P4VP) was carried out using 2,2,6,6-tetramethylpiperidin-1-oxyl (TEMPO) radical as a capping agent. A series of different molecular weight (2169,17290 and 29900) of poly 4-vinyl pyridine (P4VP) were prepared. Then P4VP was mixed with multi-walled carbon nanotubes in a new and green system, the gas expanded liquids of CO2-DMF. A series of pressures (7.11MPa,9.56MPa,13.6MPa,14.6MPa and 16.0MPa) were chosen along the vapor-liquid bubble point curves of CO2-DMF at constant temperature 125℃. Finally, carbon nanotubes were successfully modified by P4VP in CO2-DMF. The P4VP modified MWNT can be dispersed not only in organic solvents but also in the aqueous solution of acid. Furthermore, the modified MWNT was characterised by TGA, TEM and Raman Spectra. The results show that it has more advantages in gas expanded liquids than in conventional solvents. We can not only much reduce the amount of organic solvent usage but also control the polymer grafting yield on MWNT by facile pressure tuning of GXLs.
        

气体膨胀液体的热力学性质研究及其在碳纳米管功能化修饰中的应用

摘要4-6
Abstract6-7
目录8-11
第一章 前言11-30
    1.1 气体膨胀液体的概念、性质和特点12-30
        1.1.1 气体膨胀液体12
        1.1.2 CO_2在不同溶剂中的溶解度12-16
        1.1.3 研究气体膨胀液体相行为及膨胀率的设备16-17
        1.1.4 气体膨胀液体的偏摩尔体积和溶剂结构17
        1.1.5 气体膨胀液体引起的性质变化17-24
            1.1.5.1 气体膨胀液体的溶剂参数特征:极性及氢键接受-给予能力17-19
            1.1.5.2 熔点的改变19-21
            1.1.5.3 传输性质的改变21-23
            1.1.5.4 传导性质的改变23
            1.1.5.5 酸度的改变23-24
        1.1.6 气体膨胀液体的溶解力的变化24-27
            1.1.6.1 对固体的溶解度的影响24
            1.1.6.2 对气体溶解度的影响24-26
            1.1.6.3 混溶性的变化26-27
        1.1.7 气体膨胀液体的应用27-28
            1.1.7.1 超细材料的制备27
            1.1.7.2 作为化学反应介质27-28
            1.1.7.3 作为过程处理溶剂28
        1.1.8 研究背景、研究课题的选定及研究内容28-30
            1.1.8.1 为什么选择气体膨胀液体作为研究方向?28
            1.1.8.2 本工作的研究内容28-30
第二章 气体膨胀液体中的化学平衡30-41
    2.1 研究背景30
    2.2 实验部分30-34
        2.2.1 实验试剂30-31
        2.2.2 体积膨胀测定的实验步骤31-32
        2.2.3 UV-Vis实验仪器及步骤32-34
    2.3 结果与讨论34-40
        2.3.1 体积膨胀系数(α)34-36
        2.3.2 紫外吸收光谱峰的归属36-37
        2.3.3 异构化平衡常数的定量计算37-39
        2.3.4 EAA的异构平衡常数与压力及膨胀系数的关系39-40
    2.4 小结40-41
第三章 气体膨胀液体中碳纳米管的聚合物功能化修饰研究41-65
    3.1 综述41-51
        3.1.1 碳纳米管的结构41-43
        3.1.2 碳纳米管的性能43-44
            3.1.2.1 碳纳米管的力学性能43-44
            3.1.2.2 碳纳米管的电学性能44
            3.1.2.3 碳纳米管的热学性能44
        3.1.3 碳纳米管的用途44-45
        3.1.4 碳纳米管的制备45-46
        3.1.5 碳纳米管的纯化46-47
        3.1.6 碳纳米管的改性与修饰47-50
            3.1.6.1 碳纳米管的局限性47-48
            3.1.6.2 碳纳米管改性的方法48-49
            3.1.6.3 碳纳米管的共价修饰和聚合物接枝49-50
        3.1.7 气体膨胀液体的特点及进行化学反应的优势50
        3.1.8 研究课题的提出和主要研究的内容50-51
    3.2 实验部分51-55
        3.2.1 实验原料51
        3.2.2. 实验设备51-52
        3.2.3 实验中所用试剂及原料的处理52-53
            3.2.3.1 过氧化苯甲酰(BPO)的处理52
            3.2.3.2 4-乙烯基吡啶的处理52
            3.2.3.3 N,N-二甲基甲酰胺(DMF)的处理52-53
        3.2.4 材料的制备53-54
            3.2.4.1 不同分子量聚4-乙烯基吡啶(P4VP)的制备53
            3.2.4.2 聚4-乙烯基吡啶接枝的多壁碳纳米管(P4VP-CNT)的制备53-54
        3.2.5 测试仪器与表征54-55
            3.2.5.1 聚4-乙烯基吡啶的GPC表征54
            3.2.5.2 P4VP-CNT的表征54-55
            3.2.5.3 P4VP-CNT的透射电镜(TEM)表征55
            3.2.5.4 P4VP-CNT的热重分析(TG)55
            3.2.5.5 P4VP-CNT的拉曼表征55
    3.3. 结果与讨论55-64
        3.3.1 不同分子量的聚4-乙烯基吡啶的合成及表征55-56
        3.3.2 聚4-乙烯基吡啶修饰多壁碳纳米管的合成及表征56-64
            3.3.2.1 聚4-乙烯基吡啶修饰多壁碳纳米管(P4VP-CNT)在不同溶剂中的分散性57-59
            3.3.2.2 聚4-乙烯基吡啶修饰多壁碳纳米管(P4VP-CNT)的拉曼表征59
            3.3.2.3 压力对聚4-乙烯基吡啶接枝率的影响59-61
            3.3.2.4 聚合物的分子量对聚4-乙烯基吡啶接枝率的影响61-62
            3.3.2.5 聚4-乙烯基吡啶修饰碳纳米管的电镜照片62-64
    3.4 结论与展望64-65
参考文献65-71
致谢71
        下载全文需10


本文地址:

上一篇:超导材料性质和半导体表面重构及表面合金性质
下一篇:在不同适应值下误差阈的研究

分享到: 分享气体膨胀液体的热力学性质研究及其在碳纳米管功能化修饰中的应用到腾讯微博           收藏
评论排行
公告