基于不同方法的单壁碳纳米管选择性分离

发布时间：2018-01-30 03:18

  本文关键词： 单壁碳纳米管 共轭聚合物 双水相 分离 半导体/金属 窄手性　出处：《合肥工业大学》2015年硕士论文　论文类型：学位论文

【摘要】：单壁碳纳米管(Single-Walled Carbon Nanotubes, SWCNTs)具有优异的电学、力学、光学性能,因此具有非常大的潜力应用于纳米器件、传感器、透明导电薄膜和复合材料等领域。但目前通过正常的制备方法还无法得到单一导电属性和电子结构的SWCNTs.因此,如何快速有效地分离金属性(m)-SWCNTs和半导体性(s)-SWCNTs,并且得到高纯度的s-SWCNTs和各种手性的SWCNTs,成为当前碳纳米管研究工作所面临的巨大挑战。共轭聚合物的选择性分离是一种重要的分离手段,主要是通过SWCNTs与聚合物之间的π-π相互作用进行分离,用于分离SWCNTs的聚合物可以分为三类：芴基聚合物、噻吩基聚合物和咔唑基聚合物,此方法可以得到高纯度的s-SWCNTs,这对诸多高端科技领域的传感器、电子器件、场效应晶体管(FETs)是极其重要的。另外,利用双水相法分离SWCNTs,分离过程中不会破坏SWCNTs的本征结构,并且设备简易、流程简单、方便、时间短,有望实现SWCNTs的宏量分离,具有很好的发展前景。本文研究的主要内容如下：(1)首先选取四种不同种类的原始SWCNTs,利用热重分析(TG)、场发射电子显微镜(SEM)、紫外-可见光-红外(UV-vis-IR)吸收光谱、Raman光谱和原子力显微镜(AFM)表征方法对碳管原料进行定性的表征,了解每种SWCNTs的基本特征,选择HiPCO和arc-SWCNTs作为接下来分离的原料碳管。(2)基于共轭聚合物的非共价键选择性分离,设计合成了三种基于咔唑的共轭聚合物。首先探究了不同溶剂对聚合物分散arc-SWCNTs的影响,我们发现在极性最大的四氢呋喃中分散的SWCNTs浓度最高但没有选择性；在极性适中的邻二甲苯中,可以分离出高纯度的s-SWCNTs;在极性比较小的甲苯中,分散剂对SWCNTs溶解度最小,但对s-SWCNTs有一定的选择性。原因主要是不同极性的溶剂,导致高分子量的聚合物在溶液中改变自身构型。然后探究了不同结构的共轭聚合物对分散arc-SWCNTs的影响,发现PCO对半导体碳管的选择性最好,PCP对半导体碳管的选择性也非常好,并且它更倾向于选择直径较小的s-SWCNTs,而PCBP对s-SWCNTs的选择性最差。原因是吡啶结构的加入影响聚合物的几何构型和聚合物与SWCNTs之间的能量匹配。(3)采取双水相分离法,利用几种不同的表面活性剂,成功分离了不同导电属性的arc-SWCNTs和不同导电属性、直径、窄手性的HiPCO-SWCNTs.首先利用胆酸钠(SC)、十二烷基硫酸钠(SDS)和硫氰化钠(NaSCN)盐在20℃下分离s/m-SWCNTs,阐述了二次分离的方法提纯SWCNTs和两种富集碳管的方法,以及扩大浓度、体积的可实施性。基于SC和脱氧胆酸钠(DOC)的ATP体系对HiPCO-SWCNTs的选择性不同,进行SC、SDS以及NaSCN对s/m-SWCNTs表面亲疏水性调制,实现了HiPCO-SWCNTs的m/s分离。随后进一步通过精确控制DOC和SDS表面活性剂浓度,联合连续多步分离策略,实现了高纯度的不同直径和窄手性的s-SWCNTs分离。
[Abstract]:Single-Walled Carbon Nanotubeses (SWCNTs) have excellent electrical, mechanical and optical properties. Therefore, there is a great potential to be used in nanodevices, sensors. Transparent conductive thin films and composite materials. But through the normal preparation method can not get a single conductive properties and electronic structure of SWCNTs. therefore. The high purity s-SWCNTs and various chiral SWCNTs can be obtained by separating the gold attributes (MS-SWCNTs) and semiconductive sapphire SWCNTs quickly and effectively. The selective separation of conjugated polymers is an important means of separation. It is mainly separated by 蟺-蟺 interaction between SWCNTs and polymer. The polymers used to separate SWCNTs can be divided into three types: fluorene polymer. Thiophene based polymers and carbazolyl polymers can be obtained by this method with high purity s-SWCNTswhich are used for many high-end science and technology fields of sensors and electronic devices. Field effect transistor (FET) is very important. In addition, the separation of SWCNTs by two-phase water method will not destroy the intrinsic structure of SWCNTs during the separation process, and the equipment is simple and the flow is simple. Convenient, short time, it is expected to achieve macro separation of SWCNTs, which has a good development prospects. The main contents of this paper are as follows: 1) first of all, four different kinds of original SWCNTs are selected. Thermogravimetric analysis (TGN), field emission electron microscopy (EEM) and UV-vis-IR (UV-vis IR) absorption spectra were used. Raman spectra and atomic force microscopy (AFM) characterization methods were used to characterize carbon tube materials qualitatively and to understand the basic characteristics of each kind of SWCNTs. HiPCO and arc-SWCNTs were selected as the next raw materials for the separation of carbon tubes. 2) Non-covalent bond selective separation based on conjugated polymers. Three kinds of conjugated polymers based on carbazole were designed and synthesized. Firstly, the effects of different solvents on polymer dispersed arc-SWCNTs were investigated. We found that the concentration of dispersed SWCNTs in tetrahydrofuran with the highest polarity was the highest but no selectivity. High purity s-SWCNTscan be separated from o-xylene with moderate polarity. In toluene with low polarity, the solubility of dispersant to SWCNTs is the least, but the selectivity to s-SWCNTs is certain. The main reason is the solvent with different polarity. The effects of conjugated polymers with different structures on the dispersion of arc-SWCNTs were investigated. It is found that the selectivity of PCO to semiconductor carbon tubes is the best and the selectivity of PCO to semiconductor carbon tubes is also very good, and it is more inclined to choose s-SWCNTs with smaller diameters. The selectivity of PCBP to s-SWCNTs was the worst, because the addition of pyridine affected the geometry of polymer and the energy match between polymer and SWCNTs. Two water phase separation method is adopted. Using several kinds of surfactants, the arc-SWCNTs with different conductive properties and different conductive properties, diameters were successfully separated. Narrow chiral HiPCO-SWCNTs. first, sodium cholate was used. S / m -SWCNTs were separated by sodium 12 alkyl sulfate (SDS) and sodium thiocyanate (NaSCN) at 20 鈩，

本文编号：1475140