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1、西北师范大学 硕士学位论文 多元协同纳米材料界面的分子动力学模拟研究 姓名：孙亚玲 申请学位级别：硕士 专业：无机化学 指导教师：莫尊理 2008-06 摘 要 III 摘摘 要要 “多元协同纳米材料”是本课题组在“二元协同纳米界面材料”基础上提出的概 念，是对二元协同性和界面材料的推广与补充。它是以有效地利用化学场、光场、 电场、磁场、热场等外场诱导作用下的非平衡态协同效应为前提，以寻求有技术投 产前景的新型纳米复合材料为目的，在材料基体基础上进行多元协同纳米材料界面 结构的构建。“多元协同纳米材料”的界面设计思想是：当多元组分采取某种特殊的 界面协同后，在微观和介观尺度上形成交错的纳米尺寸
2、的性质不同的界面相区，从 而使材料具有某种功能。 纳米石墨微片(NanoG)兼具纳米结构、量子禁闭效应、优良导电导热性等特点， 有望成为下一代纳米电子元件材料，像操控波一样来操控电子。碳纳米管(CNT)因其 独特的结构，在纳米电子学、信息、纳米机电系统、材料增强、能源等领域有了新 的应用突破。树状大分子(Dendrimer)在药物、催化、分子识别等方面的应用已成为 目前研究热点，且在光学、分子电子器件等方面已崭露头角。聚吡咯(PPy)纳米管和 分子导线对纳米器件和分子器件的制造起着关键作用。因此本课题以 NanoG、 SWCNT、Dendrimer 和 PPy 为界面设计对象，用分子动力学模拟
3、技术进行了多元协 同纳米材料的界面探究、优化和设计的递进式研究。主要内容分以下三个方面： 1) 从本课题组已制备的“纳米石墨薄片/氯化银/聚吡咯(NanoG/AgCl/PPy)纳米复合 材料”入手，以实验数据为基础，用分子动力学方法模拟研究了三组分的微观和 介观界面，得到了材料性能优良所必备的界面条件。NanoG 均匀分布在 PPy 中， PPy 以导电壳层结构修饰 AgCl 颗粒， 其中 PPy 起着粘合剂的作用， 分别与 NanoG 和 AgCl 以强界面结合。 2) 将 1)中得到的条件，应用于界面材料的优化设计。实验结果表明树状大分子与 其他组分可形成可调界面，因而我们选择“树状大分子
4、/纳米石墨薄片/聚吡咯 (Dendrimer/NanoG/PPy)”导电组分，建立其界面材料模型，研究其温度效应及热 敏开关机理。 均一的分布和适当的包覆导致界面材料在360K时出现高的兼容性； 疏散的结构和弱的包覆导致材料在 340K 和 400K 时出现稳定但低兼容性结构。 PPy 和 Dendrimer 的界面兼容性对整体材料兼容性至关重要； NanoG 对界面材料 的稳定性起关键作用。Dendrimer/NanoG/PPy 界面材料通过对各温度下树状大分 摘 要 IV 子的形变控制，可实现热敏开关功能。 3) 吸取 2)中的界面优化的结果，继续利用树状大分子的可调特性及纳米碳管的功 能
5、潜质， 初步尝试了 “树枝化单壁碳纳米管(Dendronized SWCNT)协同纳米材料” 的界面设计。以 SWCNT(11,5)为核，接枝树状重复单元，形成树枝化单壁碳纳 米管。 螺旋平行包覆的结构放大了纳米碳管的手性， 整体有序的高选择性孔洞结 构增强了其在手性识别方面的应用； 并且这种树状重复单元在纳米碳管管壁的有 序突出增强了碳管的活性点，为其场致发射性能的提高奠定了基础。 关键词：关键词：多元协同纳米材料；界面设计；功能化；分子动力学模拟 Abstract V Abstract The idea of “Multiple Synergistic Nanocomposites” ba
6、sed on concept of “Binary Synergic Interfacial Nanomaterials”, and it is a further generalization and supplement of binary synergic and interfacial materials. It is on the premise of synergistic effect of none-quilibrium states under induction of chemistry or external fields of light field, electric
7、 field, magnetic field and thermal field. The goal is to seek new nanocomposites having commissioning prospect. Then to construct interfaces structure of multiple synergistic nanocomposites. The interfaces design idea of multiple synergistic nanocomposites is as follows: when the components get cert
8、ain interfacial synergic effect, interface-phase having defferent properties will be formed in muti-scales, and it will bing the composites certain functions. NanoG has nanostructure, quantum confinement effect, excellent thermal conductivity and high electrical conductivity, so it could be used as
9、electronic components materials which could be manipulated like wave. Because of their unique structure, CNT show new breakthrough in the field of nano-electronics, information field, nanotechnology, electromechanical systems, materials, energy and so on. The research hotspots of Dendrimer are the a
10、pplication in drug, catalysis, molecular recognition and special materials. Recently, it also emerged in the optical, electronic devices. PPy nano-tubes and nano-devices play a key role in manufacturing molecular wires and molecular device. Therefore we use NanoG, SWCNT, Dendrimer and PPy as interfa
11、ce design object, and research progressively in exploration, optimization and design of multiple synergistic nanocomposites. The main contents are as follows: 1) In order to get the interfacial conditions of forming excellent performance materials, our simulations start from NanoG/AgCl/PPy nanocompo
12、sites, base on experimental data, and research the microsmic and mesoscopic interfaces by molecular simulations NanoG well dispersed in PPy matrix, and the matrix were decorated by coreshell nanoparticles with AgCl as the core and PPy as the conducting shell. PPy played a key role of adhesive, which
13、 combined with NanoG and AgCl separately through Abstract VI strong advantaged interfaces. 2) Besed on above condictions, further optimization design of interface materials was conducted. It was found that adjustable interface can be formed by dendrimers and other components. Therefore, we build int
14、erface materials model of Dendrimer/ NanoG/PPy interface materials in order to reveal its work mechanism as a molecular thermoswitch (temperature sensitive switch). Effective interaction, uniform distribution and appropriate coating of interfaces lead to the high compatibility at 360K. Incompact and
15、 weak coating interfaces result in steady and low compatibility at 340K and 400K, respectively. The compatibility of interfaces between PPy and dendrimer is crucial for the whole compatibility of the Dendrimer/NanoG/PPy interface material. NanoG plays a key role in stability of the interface materia
16、l. The switch function is realized by geometry change of dendrimer driven by its interfacial interactions with polypyrrole and graphite nanosheets at various temperatures. 3) Assimilating the results of interface optimization, we used the adjustable characteristics of dendrimer and the potential functions of CNT to design Dendronized SWCNT synergistic nanocomposite. When SWCNT(11,5) was decorated with dendrimer units, it got a spira
