传统微柱表面在控制低表面张力流体浸润方面受到许多挑战，近年来，受弹尾虫表面等仿生结构的影响，在微柱表面中加入微腔组成“腔柱协同体系”控制流体浸润成为超拒液材料研究领域的热点。同时，微腔结构在水收集、物理抗菌、微流控、水下减阻和油水分离等工业领域都具有重要应用价值。然而长久以来，对微腔表面的认知局限为微柱“反结构”，对微腔润湿行为的解释仍沿用以Cassie-Baxter模型为代表的粗糙表面润湿理论，忽略了微腔内部气液界面变化对液滴润湿转变的影响，目前对微腔表面控制低表面张力流体浸润的研究较少，且微腔表面对液滴蒸发的影响上尚无研究，导致对一些液滴浸润现象的认识不足，这阻碍了微腔结构在新型功能材料表面的进一步应用。针对上述问题，本文较为系统的研究了低表面张力液滴在微腔表面的浸润现象，重点考虑了微腔内部气液界面变化对整个液滴浸润转变的影响，建立相关力学模型和标度关系解释微腔表面液滴浸润现象，同时探究了微腔对胶体液滴蒸发及颗粒沉积的影响。
通过软光刻技术制备了具有不同粗糙度和固体份数的PDMS微腔表面，搭建了满足实时观测和长时间记录要求的液滴运动观测设备，借鉴干涉条纹分析，获取了微腔内部气液界面的形貌，并进一步研究了微腔内气液界面介观演化与宏观尺度液滴铺展之间的关联机制。结果表明，对在微腔表面的非蒸发低表面张力液滴，其铺展形状与微腔排列方式对应，液滴在微腔表面铺展过程分为快速铺展、显著钉扎以及定向润湿转变三个阶段。基于实验数据，通过宏观特征（液滴运动速度、润湿维持时间等）与介观尺度变量（气液界面）的关系建立了微腔内部气液界面演化的力学模型。分析表明，微腔内部初始气液界面形状是液滴在Cassie状态持续时间的决定因素，同时发现液滴铺展过程中的定向润湿转变时间与铺展距离满足时空幂律关系R~tⁿ。
  在上述研究基础上，借助梯度微腔表面，进一步从微-介观尺寸研究了液滴润湿转变在不同粗糙度的微腔表面的差异。通过研究发现，微腔内部气液界面最长演化时间与微腔分数以及液体黏度成正比，液滴铺展面积与微腔粗糙度成反比。基于实验结果，结合聚合物流变学，建立了微腔表面低表面张力液滴润湿转变的唯象模型，发现只有当考虑液滴内部大分子链的黏弹特性在相邻微腔中互相传递时才能解释演化时间与微腔分数的正比关系。该工作阐明了相邻微腔的气液界面演化会彼此影响，这解释了微腔表面对低表面张力液滴在Cassie润湿状态的超长时间维持现象，完善了微腔表面对低表面张力流体的拒液机制。
  开展了微腔表面胶体液滴的蒸发观测实验研究。通过分析胶体液滴在亲/疏水微腔表面的蒸发动态特征和颗粒沉积结果，发现在疏水微腔表面，形貌因素增强了液滴在蒸发过程中的接触线波动跳跃现象，区别于光滑表面，微腔形貌阻碍了液膜的向内破裂收缩，蒸发中不存在常接触角模式。对于亲水微腔表面，液滴蒸发过程分为常接触面积蒸发阶段、薄液膜快速蒸发阶段、微腔内部残余液体蒸发阶段。研究发现，薄液膜快速蒸发中微腔边缘接触线破裂导致微腔边缘极易产生干区，且微腔对周围粒子存在“抽吸效应”，导致粒子在后退接触线的补偿回流曳力带动下向微腔内部加速聚集，力学分析表明颗粒在接触线处的不均匀受力是导致颗粒组装的关键。该工作完善了液滴在微腔表面的蒸发和颗粒沉积理论。
  另外，本文还探索了球形压痕法在表征聚合物应力软化效应和反演本构参数方面的应用，证明了球形压痕法对应力软化测试的可行性；通过分析纳米颗粒填充聚合物对循环压缩载荷的机械响应结果，发现能量耗散随着填料体积分数在一定范围内的增加而增强，该研究有助于聚合物材料的性能改进和测试方法优化。

  Traditional micropillar surfaces have faced many challenges in controlling the fluids with low surface tension. In recent years, inspired by biomimetic structures such as Collembola surface, combining microcavities and micropillars to form "cavity-pillar synergistic system" has become research hotspots to achieve liquid-repellent and fluid control. Also, microcavity surface has important application value in many industrial fields such as water collection, self-cleaning and anti-microbico, microfluidics, underwater drag reduction and oil-water separation, etc. However, for a long time, the cognition of the microcavity surface has been limited to the "inverse micropillar structure". The wetting theory of microcavity surface still follows the rough surface wetting theory represented by Cassie-Baxter wetting model. The effect of the gas-liquid interface inside cavity on the wetting transition is neglected to some extent. At present, there are few studies on the control of low surface tension fluid infiltration and the changes of gas-liquid interface on the microcavity surface, leading to insufficient understanding about the effect of microcavity on the droplet wetting transition and evaporation, which hinders the applications of microcavity structure in liquid-repellent engineering. In view of the above problems, this doctoral dissertation studies the spreading and wetting transition characteristics of low surface tension droplets on microcavity surface, and focuses on the influence of air-liquid interface inside microcavity, and establishes mechanical models and scaling relationship to explain the wetting phenomenon on microcavity surface. The influences of the microcavity on colloidal droplet evaporation and particle assembly are also explored.
PDMS microcavity surfaces with different roughness and solid fraction were prepared by deep silicon etching and soft lithography. Multi-dimensional droplet motion observation system that met the functions of real-time observation and long-term recording was built. The morphology of air-liquid interface inside the microcavity was obtained by reference interference fringe analysis technology. This paper studies the mechanism between mesoscopic evolution of the air-liquid interface and macroscopic droplet spreading. For the non-evaporative low surface tension droplets on the microcavity surface, the spreading shape of droplet corresponds to the arrangement of the microcavity. The droplet spreading on microcavity surface can be divided into rapid spreading stage, pinning stage and directional wetting transition stage. Based on experimental data, the mechanical evolution model of air-liquid interface in the microcavity is established by using the relationship between macroscopic variables (droplet velocity, time, etc.) and mesoscopic variables (air-liquid interface). The study shows that the initial shape of air-liquid interface inside the microcavity is important determinant for the duration of Cassie wetting state. It is elucidated that the directional wetting transition phenomenon satisfies the spatiotemporal power-law relationship R~tⁿ. 
  On the basis of above research, by using gradient microcavity surface, the differences of droplet wetting transition on diverse microcavity surfaces were further studied. The study found that the evolution time of the air-liquid interface inside the microcavity is proportional to the microcavity fraction and liquid viscosity; the spreading area is inversely proportional to the microcavity roughness. Based on the polymer rheology, a phenomenological bead-spring model of the wetting transition on microcavity surface was established. It was found that the viscoelastic properties of macromolecular chains were transmitted to adjacent microcavities, which proved that the air-liquid interface evolution inside one microcavity will be affected by adjacent microcavities. This synergistic effect improve the enhanced mechanism of the Cassie-Baxter wetting state of polymer droplets on microcavity surface, and provide some theoretical basis for the design of the cavity-pillar synergistic system on the super liquid-repellent surface.
  The evaporation of colloidal droplets with micro-particles on microcavity surface are also investigated. By examining the evaporation dynamic characteristics and particle deposition results of colloidal droplets on the hydrophobic microcavity surface, it is found that the topography enhances the contact line fluctuation and jumping phenomenon during droplets evaporation process. Unlike smooth surfaces, there is no constant contact angle satge, and the microcavity topography hinders the inward shrinkage and rupture of liquid film. It is proposed that the droplet evaporation on the surface of the hydrophilic microcavity can be divided into the CCR evaporation stage, the rapid evaporation stage of the thin liquid film, and the evaporation stage of the residual liquid inside the microcavity. It was found that the reason of dry zone formation in the particle assembly was the breakage of liquid film at the edge of the microcavity during the rapid evaporation stage. At the same time, the "pumping effect" of the microcavity on the surrounding particles led to the accelerated aggregation of particles into the microcavity driven by the compensating backflow drag force. A related model was established to explain the mechanism of particle assembly on the microcavities surface. This study provides a theoretical basis for the development of shape control of coffee ring.
  In addition, this paper also explores the application of spherical indentation method in the characterization of stress-softening effect and the inversion of constitutive parameters of polymer materials. The mechanical response to cyclic compressive load was found to be enhanced with the increase of filler volume fraction within a certain range. This research can provide support for polymer material performance improvement and testing procedure optimization.