通过grafting from技术修饰纳米粒子的计算机模拟研究

We mean to use coarse-grained molecular dynamics simulation method combined with chemical reactions, to study the controlling factors during modification of nanoparticles by polymer chains via the surface-initiated polymerization (grafting from method). The features of initiation efficiency, grafted chain polydispersity, etc, will be mainly analyzed. Meanwhile, the controllability of molecular weight and structure of grafted chains, and their dependences on temperature, solvent quality will also be studied. As a further investigation, we will construct the system of multiple nanoparticles with size/shape distributions in the dilute solution. Then we will design the potential of mean force between nanoparticles. By scanning the free energy change of nanoparticles in specific reaction path, we can understand the intrinsic nature of the interactions between nanoparticle individuals. This project will provide theoretical direction for the experimentalists to prepare and optimize the new functional polymer nanocomposite materials.

本项目拟发展并利用耦合化学反应的粗粒化分子动力学模拟方法，研究表面引发聚合反应（grafting from方法）对纳米粒子改性过程中的主控因素，分析体系在引发效率、链多分散性等方面的特点。同时研究接枝链的分子量及结构的可控性，以及温度、溶剂等其它因素对表面微结构的影响。进一步探讨具有形状和尺寸分布的纳米粒子体系的表面修饰问题，建立多纳米粒子在稀溶液环境中的共体系统，构建改性纳米粒子之间的平均力势。通过扫描纳米粒子在某反应路径的自由能变化，加深对纳米粒子个体之间相互作用本质的认识。为实验上制备、优化新型聚合物纳米复合材料提供可靠的理论帮助。

本项目围绕配体链接枝纳米粒子的改性技术中的诸多问题而展开。通过粗粒化分子动力学模拟方法，对grafting-from及grafting-to技术中的主控因素进行了系统性的研究。通过特定的测地线细分方法构造了粗粒化纳米粒子模型，并构建了聚合反应的分子动力学模型，给出了grafting-from过程中生长链受纳米粒子尺寸、packing fraction等因素的影响关系；发现了链增长的分散性对引发密度和引发剂非均一性参数的定量依赖关系；并构造了grafting-to技术制备纳米粒子接枝配体链的分子动力学模型，得到了重要的研究结论，即投料聚合物链的分散性相对较高很可能有利于提升制备纳米粒子接枝链的接枝密度；同时我们参与开发了粗粒化的逐步聚合反应模型及SKIPS-GALAMOST聚合反应模拟研究平台。