剪切场下纳米粒子在官能化橡胶基体中有序结构的形成机制研究

The use of a shear field is an effective means to induce the ordering and orientation of nanoparticles in rubber matrix. However, a significant disadvantage of shear to order nanoparticles is that once the flow is removed the ordered structures decompose into disordered particles again due to the relaxation of the matrix chains. Based on the previous studies, this project seeks to solve this problem via rational functionalization of polymer chains. To provide thorough understanding into this respect, this project will employ molecular dynamics simulation, which is of great advantage in revealing microstructure evolutions under both equilibrium and non-equilibrium conditions, to investigate the arrangement behaviors of nanoparticles in functionalized rubber matrix under quiescent, steady shear and oscillatory shear conditions, as well as during the relaxing process after ceasing shear. The influences of various factors, including the shear conditions and the physical and chemical properties of the functionalized rubber, will be explored. The mechanism of how shear field induce the ordering of nanoparticles in functionalized rubber matrix will be revealed, and the underlying mechanism of why shear-induced ordered nanoparticle structures can be maintained after the cessation of shear will also be clarified. Finally, we will carry out some experimental work to verify the simulation results. The execution of this project will provide theoretical guidance to the designing of high-performance functional rubber nanocomposites, the developing of processing technology, and the studying of structure-property relationship of the rubber nanocomposites.

剪切场是诱导纳米粒子在橡胶基体中发生有序排列和取向的有效手段，但其缺点是当剪切停止后这种有序结构由于分子链的松弛很容易恢复无序状态。基于前期研究工作，本项目提出通过对高分子链进行合理的官能化改性，解决剪切停止后有序结构难以保持稳定这一关键科学难题。为深化对其机制的认识，本项目拟利用分子动力学模拟易于实现在线追踪微观结构在动静态条件下演变行为的优势，对静态（未施加剪切）下、稳态剪切与振荡剪切下、以及剪切停止后，纳米粒子在官能化橡胶基体中的排列行为进行系统研究，探索剪切条件与官能化橡胶的物理化学特性对纳米粒子排列行为的协同影响，揭示剪切场对纳米粒子排列行为的调控机制，阐明剪切停止后纳米粒子有序排列结构保持稳定的微观机理。最后我们将辅以实验研究，以对模拟结果进行验证。通过本项目的研究，有望为高性能功能性橡胶纳米复合材料的设计、加工技术开发、结构-性能研究提供理论指导。

本项目利用分子动力学模拟易于实现在线追踪微观结构在动静态条件下演变行为的优势，对静态（未施加剪切）下、稳态剪切与振荡剪切下、以及剪切停止后，纳米粒子在官能化橡胶基体中的排列行为进行了系统研究。通过系统粗粒化法构建了官能化丁苯橡胶-白炭黑纳米粒子复合体系粗粒化模型，探明了橡胶分子链及纳米粒子的官能化改性对纳米填料分散与自组装行为的影响机制，给出了剪切过程中纳米粒子排列行为受剪切条件、官能化分子链序列结构等因素的影响关系，揭示了剪切场对纳米粒子排列行为的调控机制，明晰了剪切停止后粒子有序结构保持稳定的动力学机制。最后我们通过实验研究，验证了橡胶分子链官能化改性对改善填料分散的意义。通过本项目的研究，有望为高性能功能性橡胶纳米复合材料的设计、加工技术开发、结构-性能研究提供理论指导。