Nat Mater. 2011 Sep 11;10(11):867-71. doi: 10.1038/nmat3117.
Crystallization of a molecular liquid from solution often initiates at solid-liquid interfaces, and nucleation rates are generally believed to be enhanced by surface roughness. Here we show that, on a rough surface, the shape of surface nanopores can also alter nucleation kinetics. Using lithographic methods, we patterned polymer films with nanopores of various shapes and found that spherical nanopores 15-120 nm in diameter hindered nucleation of aspirin crystals, whereas angular nanopores of the same size promoted it. We also show that favourable surface-solute interactions are required for angular nanopores to promote nucleation, and propose that pore shape affects nucleation kinetics through the alteration of the orientational order of the crystallizing molecule near the angles of the pores. Our findings have clear technological implications, for instance in the control of pharmaceutical polymorphism and in the design of 'seed' particles for the regulation of crystallization of fine chemicals.
从溶液中结晶分子液体通常从固液界面开始，并且普遍认为成核速率可以通过表面粗糙度来提高。在这里，我们表明，在粗糙表面上，表面纳米孔的形状也可以改变成核动力学。我们使用光刻方法，用各种形状的纳米孔对聚合物薄膜进行了图案化处理，发现直径为 15-120nm 的球形纳米孔阻碍了阿司匹林晶体的成核，而相同尺寸的角形纳米孔则促进了成核。我们还表明，角形纳米孔促进成核需要有利的表面-溶质相互作用，并且提出孔形状通过改变靠近孔角处结晶分子的取向有序性来影响成核动力学。我们的发现具有明确的技术意义，例如在控制药物多晶型和设计用于调节精细化学品结晶的“晶种”颗粒方面。
