Pingan Zhu,Tiantian Kong,Chunmei Zhou,Leyan Lei,Liqiu Wang
Natural systems have exceptional capabilities of constructing structures across multiple length scales for remarkable performances from limited choices of building blocks. However, simultaneous control over structures at both the macroscopic and microscopic length scales is restricted by the high requirements in the type and property of building blocks. Here, directed self-assembly of microdroplets in an evaporating liquid is harnessed to fabricate large-scale ordered films with precisely controlled microstructures. Evaporation-induced variations in liquid confinement allow microdroplets to reassemble for large-scale ordered patterns. Deformation of microdroplets into different shapes accurately defines multiple topographical structures at the microdroplet level. The fabrication process is facile and scalable, and works with various materials for manufacturing functional films with tunable properties. These results suggest a facile yet effective strategy for engineering microstructures by combining directed self-assembly with manipulation of the property of building components for both structural fidelity and diversity.
Secondary hydration is the main driving force of autogenous self-healing and directly impacts the closure of cracks in damaged cementitious materials . In fiber-reinforced cement composites , secondary hydration also dominates the regeneration of the fiber-matrix interface during the self-healing processes. As an important factor influencing the cement hydration , silica fume (SF) addition can be crucial to the self-healing performance of cementitious materials and composites. In this paper, the effect of SF on the autogenous self-healing of ultra-high-performance fiber-reinforced concrete was investigated. With a ≥20% SF addition, the secondary hydration the cement matrix adjacent to the cracks was accelerated. The dissolution of amorphous silica and the formation of Si-containing healing phases was observed. These effects predominated the closure of the mouth and the inner part of the cracks. SF addition also enhanced the regeneration of fiber-matrix interface by promoting the growth of self-healing products in these areas. The closure of cracks and the regeneration of fiber-matrix interface are both responsible for the restoration of flexural properties.
危险品化学品经营许可证（带存储）