纳米聚苯胺成核机理的研究：结构演变与分子作用机制

项目名称： 纳米聚苯胺成核机理的研究：结构演变与分子作用机制

项目编号： No.21474053

项目类型： 面上项目

立项/批准年度： 2015

项目学科： 数理科学和化学

项目作者： 武晓东

作者单位： 南京理工大学

项目金额： 80万元

中文摘要： 目前对导致纳米聚苯胺各向异性生长为特定形貌最关键一步：游离寡聚物分子变为电镜可观测的聚集态过程的认识异常匮乏，这归因于此转变过程速度快，分子间作用力复杂及成核物种稀少使相关信号衰减过快，强度过弱，重叠严重而难以捕捉与解析。最近我们发现以胶粒水化层中的水分子为探针结合诸共振吸收峰随反应时间的变化规律可破解此难题，因为胶粒水化层中水分子同样感受成核变化，载有成核信息，但其绝对数目多，能及时反映成核环境变化。 目前囿于此类分子能与本体水分子发生快速交换使信号平均化而难以开展相关工作，我们通过增大胶粒尺寸以增加水化层厚度减缓以上交换过程并增强其抵抗成核冲击的能力使检测成为可能。本申请拟在此基础上进一步采纳选择性激发与脉冲梯度场技术将二维核磁降维为一维核磁定性与定量地揭示聚苯胺成核过程中聚集态结构演变与分子作用机制，重点考察偶极作用的变化规律。本工作对全面认识有机乃至无机纳米材料的成因具有重要意义。

中文关键词： 自组装；聚集态结构；原位核磁共振；胶粒水化层；偶极作用

英文摘要： Current understanding on the anisotropic growth from the aniline oligomers to polyanilines in different morphologies is limited due to the shortage of the appropriate methodology to characterize this process. The major difficulties come from the following aspects:1) the number of the nuclei is scare which makes the signal is too feeble to be detectable; 2) the signal evolves too fast due to the transient nature of this process; and 3) all interested signals are overlapped severely, leading the spectral interpretation significantly hard. Fortunately,we observed the water molecules in the solvation layer of the micelle can be served as the ideal probe molecules for the detection of the nucleation mechanism due to the following considerations:1)all molecules involved in the nucleation carries the information of this process, and therefore theoretically the detection of water molecules enables us to derive the same information as those from other species;2)these molecules are large in number and can respond to the external interruptions quickly due to their high mobility, making them the best probes for detection. While superior in nature, these molecules can exchange fastly with the water molecules in bulk leading to an average signal observed eventually which encumbers their applications in the mechanistic studies. To overcome this difficulty, we found that culturing the micelle into a bigger size can increase the thickness of the solvation layer while enhance the capability of the water molecules therein withstanding the violent shocking from the other species' structural arrangements in the nucleation.In this way,those water molecules carrying the information of nucleation have a life time long enough and enable to be served as the ideal probe moelcules for the detection. On the basis of these results, we are trying to carry out the gradient selected pseudo-two dimensional NMR experiments via selective excitating the resonances from species such as water or in situ formed oligomers in the reaction.Our main focus is on the understanding the structural evolution and the molecular interactions underneath each transition, in paticular the evolution of the dipolar couplings of the major species in the nucleation period. In summary, we are endeavored to dig out the predominant step-wised proedures for the formation of major polyaniline nanotructures (such as nanotubes, nanorod, nanosponges and so on)as well as the major intermolecular interactions that dictate the corresponding structural generation. This projection is of fundamental importance for the understanding of the formation mechanism of nanostructured materials and the nature of the self-assembly process and thus will be of great value in academic and industry.

英文关键词： self-assembly;aggregated structures;in-situ NMR;hydration layer in micelles;dipolar interactions