聚合物/纳米粒子体系的长程有序化及其力学性能研究

Inspired by nature, the experimentalists exploit process of solvent vapor annealing to direct self-assembly of polymers and nanoparticles into hierarchical, long-range ordered nanostructures, which are subsequently utilized to prepare bio-inspired nanocomposites with enhanced mechanical properties. Currently, it is challenging to rationally design bio-inspired nanocomposites, because of poor understanding of long-range ordering of nanoparticles in the polymer matrix and relationship between mesoscopic morphology and mechanical properties. In this proposal, focusing on the polymer/nanoparticle systems, we will build upon model of solvent vapor annealing with hydrodynamic effect, and develop parallel algorithm for the simulations of kinetic behaviors. We intend to investigate the process of solvent vapor annealing for the polymer/nanoparticle systems, and unveil the long-range ordering mechanisms of nanoparticles in the polymer matrix. Furthermore, the lattice spring model is integrated to predict the mechanical properties of polymer/nanoparticle systems, and the effects of nanoparticle architecture and solvent vapor annealing on the mechanical properties are explored. On the basis of these studies, we present the optimum architecture of nanoparticles and parameter of solvent vapor annealing for creating the thin film of long-rang ordered nanoparticles embedded in the polymer matrix with the feature of enhanced mechanical properties. These studies provide insights into the nature of nanoparticle arrangement with long-range ordering, and furthermore offer promising strategies for constructing the bio-inspired nanocomposites.

受大自然启发，实验学家以聚合物和纳米粒子为构筑单元，通过溶剂蒸汽退火工艺获得了多层次、长程有序纳米结构，并用于制备力学性能优异的仿生复合材料。由于纳米粒子的长程有序化机理及介观形态—力学性能关系仍不明确，理性地设计高性能仿生复合材料仍有很大的挑战。本项目以聚合物/纳米粒子体系为研究对象，（1）建立包含流体动力学效应的溶剂蒸汽退火模型，发展适用于大尺度动力学模拟的并行算法；（2）开展聚合物/纳米粒子体系的溶剂蒸汽退火模拟，揭示溶剂蒸汽退火过程中纳米粒子长程有序化的机理；（3）结合网格弹簧振子模型，掌握纳米粒子的结构参数和溶剂蒸汽退火的工艺参数对聚合物/纳米粒子体系力学性能的影响规律。在此基础上，通过设计纳米粒子结构和优化溶剂蒸汽退火工艺，以期获得长程有序、力学性能优异的聚合物/纳米粒子薄膜。通过上述研究，为高性能仿生复合材料的理性设计提供新思路和理论支持。

针对纳米粒子的长程有序化机理及介观形态—力学性能关系不明确的科学问题，本项目发展了共聚物/纳米粒子复合体系的杂化动态自洽场/分子动力学模拟方法和网格弹簧振子模型，开展了复合体系的长程有序化机理及其力学性能的研究。取得的重要结果如下：（1）实现了聚合物体系动力学模拟并行算法，揭示了溶剂蒸汽退火下垂直取向层状相的形成起源和参数范围。（2）构建共聚物/纳米粒子体系的局域退火模型，实现了复合体系的长程有序纳米结构并调控了纳米粒子的定向运动行为。（3）提出了动力学调控共组装路径的方案，揭示了纳米粒子的外延生长过程，并证实长程有序纳米结构具有良好的力学性能。（4）此外，阐明了DNA功能化纳米粒子自组装形成一维长程有序纳米聚合物和共聚物过程，实现了纳米聚合物的长度、序列等调控和预测。以上模拟结果为长程有序化纳米结构的动力学路径设计提供了新思路和理论支持。