高分子/纳米粒子复合物溶剂蒸发成膜及结构调控的计算机模拟

The aim of this project is to develop a simulation technique for the investigation of the solvent evaporation process for polymer/nanoparticle composite systems. First of all, in order to faithfully modelling a continuous solvent evaporation process with a controlled evaporation rate, we will develop a constant chemical potential molecular dynamics simulation technique. We will also integrate this simulation method into GALAMOST, a GPU accelerated molecular dynamics simulation package initially developed in our group, which will fulfil the technique requirement of this project for the massive parallel molecular dynamics simulations. Based on the development of the simulation method, we will systematically perform large-scale simulations with different conditions. The influences of different factors during the solvent evaporation process on the polymer/nanoparticle (NP) composite (PNC) film formation process and the final morphology of the film will be investigated. These influence factors including solvent types used in the process, evaporation rate of the solvent, nanoparticle size, nanoparticle type, graft density and graft chain length on the NP surface, radius of gyration of polymer chain, topology of polymer chain, interactions between polymer and solvent, attraction strength of solvent or polymer on the substrate, and the post thermal annealing process in solvent vapor, will be investigated in this project. The accomplishment of this project is expected to provide reliable theoretical results and predictions which will be useful for a better design and preparation of functional polymer/nanoparticle nanocomposites.

本项目拟发展并利用粗粒化分子动力学模拟方法，研究高分子/纳米粒子复合物的溶剂蒸发成膜过程及结构调控机制。发展Constant Chemical Potential粗粒化分子动力学模拟方法，实现对蒸发速率精确可控的溶剂连续蒸发过程的真实模拟，并实现该方法在GALAMOST程序包中的GPU加速并行计算。在此基础上，利用该方法系统研究溶剂类型（单一溶剂或共溶剂）、蒸发速率、纳米粒子类型、尺寸、接枝状态、高分子链尺寸以及拓扑结构、高分子链的溶剂亲和能力、基底对高分子链及纳米粒子的吸引强度、以及利用溶剂蒸汽浴对复合物薄膜进行后处理过程中所采用的溶剂类型、饱和蒸汽压大小、处理时间等因素对复合物薄膜的成膜过程及成膜形态的影响规律和机制。为相关高分子/纳米粒子复合物薄膜的设计和制备提供可靠理论支持。

利用溶剂蒸发是制备高分子膜等材料的重要手段，该过程影响因素复杂。同时受到实验表征手段的限制，这类材料蒸发过程中的分子机理以及各种因素对蒸发过程及材料结构控制的影响机制仍不十分清楚。因此，非常有必要借助计算机模拟方法来研究在溶剂蒸发过程中各种因素对成膜过程及材料最终结构的影响规律及机制。本项目（i）发展了一种更加真实有效、稳定持续、速率可控的显式溶剂分子动力学蒸发模拟方法。（ii）利用上述方法，在针对高分子纳米复合物溶剂蒸发成膜过程中，溶剂选择性等各类因素对纳米复合物结构的影响。重点研究了溶剂对单链纳米粒子中交联剂的选择性对纳米粒子在复合物薄膜中分散性及结构的影响，发现并明晰了单链纳米粒子发生界面偏析的重要规律。（iii）系统研究了上述溶剂效应诱导的单链纳米粒子界面偏析现象在驱动嵌段共聚物定向自组装方面的潜力。（iv）作为本项目研究内容的一个重要拓展，我们提出了由接枝无机纳米粒子溶液通过溶剂蒸发制备补丁纳米粒子的新方案，并通过结合实验证明了该方案的可行性。（v）研究了两种不同的（异种）聚合物双接枝体系中，通过两种互不相容的接枝链在纳米粒子表面切向方向的相分离以及溶液蒸发下接枝链在表面的塌缩两种驱动力共同作用下，形成正交补丁纳米粒子新结构的规律。