垂直沉积自组装胶体晶体裂纹形核及裂纹扩展微观特征观察研究

The integrity of the colloidal crystal is destroyed by the cracks that formed in the colloidal crystal growth process, which limit the application of the colloidal crystal. Understanding the crack formation mechanism is important for exploring the method to suppress cracks and getting crack-free colloidal crystals. The colloidal spheres dispersion often used as a model system to study the crack formation mechanism of the drying system. There is no inner stress cumulative because of the absence of gelation process during the growth of the colloidal crystal. It's difficult to explain the formation of cracks during the colloidal crystal growth process by the existing the crack formation mechanism. In addition, the existing mechanism essentially is based on continuum mechanics and does not involve any microscopic statistical regularity, however, the cracking of colloidal crystals began at nanoparticle scale, and then expanded to the macro level. The evolution of this cross-scale process cannot be explained by the existing theory. The project is to study the appearance and propagation of the cracks of the vertically self-deposited colloidal crystal, focus on the crack nucleation and micro-expansion characteristics with the means of microscopic observations. We expect to understand crack nucleation and expansion process from the basic unit, then to elaborate crack formation mechanism of the colloidal crystal.

胶体晶体生长过程中形成的裂纹严重破坏了胶体晶体的完整性，限制了胶体晶体的应用。对胶体晶体裂纹形成机理的研究是探索裂纹抑制方法，寻求无裂纹胶体晶体的首要前提。传统的研究方法中，胶体微球分散体通常被作为一种模型试验体系用来研究干燥体系裂纹形成机理。而胶体晶体生长干燥过程中由于没有凝胶化等复杂的应力累计过程，现有的裂纹形成理论难以解释胶体晶体生长过程中裂纹产生的现象。另外，现有的研究手段本质上都是基于连续介质力学而没有涉及微结构的统计规律，而胶体晶体的开裂是从纳米颗粒尺度上产生，再扩展到宏观层次，这种跨尺度的演化过程在现有的理论中是无法找到解释。本项目主要借助垂直沉积自组装胶体晶体体系来研究晶体生长过程中裂纹的发生、扩展过程，借助显微观察手段重点关注裂纹形核及裂纹微观扩展特征。以期从最基本的单元阐述胶体晶体裂纹形核、扩展过程及机理。

胶体晶体生长过程中形成的裂纹严重破坏了胶体晶体的完整性，限制了胶体晶体的应用。对胶体晶体裂纹形成机理的研究是探索裂纹抑制方法，寻求无裂纹胶体晶体的首要前提。以显微观察为手段，研究了裂纹形核特点、分布特征；观察裂纹的扩展特征以及缺陷对裂纹影响。通过观察单层微球干燥过程研究了微球间毛细作用对胶体微球的控制作用。通过上述研究，来揭示裂纹形成机制以及寻求抑制裂纹的方法。