A hierarchical flower-like ordered arrangement of the pores in the porous film was explored by combination of the breath figure technique and layer-by-layer solution casting process. A layer-by-layer polymers system of polystyrene (PS) and polyimide (PI) was used to form uniform surface for the casting instead of the non-uniform surface of blended polymers. From top and cross-sectional SEM images, surface flower-like pores, and bottom spherical pores interconnected each other are imaged. The pore shape was tunable from spherical to obovate by controlling the interfacial tension between the condensed water and the polymer solution. Based on the deep experimental observation, the formation mechanism for flower-like ordered hierarchical porous structure was proposed.

通过呼吸图形技术和逐层溶液浇铸工艺相结合，探索了多孔膜中孔隙的分层花状有序排列。聚苯乙烯 (PS) 和聚酰亚胺 (PI) 的逐层聚合物体系用于形成均匀的铸件表面，而不是混合聚合物的不均匀表面。从顶部和横截面 SEM 图像中，可以成像表面花状孔和底部球形孔相互连接。通过控制冷凝水和聚合物溶液之间的界面张力，孔的形状可以从球形调节到倒卵形。在深入实验观察的基础上，提出了花状有序分级多孔结构的形成机制。