Department of Chemistry, Virginia Commonwealth University, Richmond, Virginia 23284-2006, USA.
Langmuir. 2012 May 15;28(19):7492-7. doi: 10.1021/la301560r. Epub 2012 May 2.
A straightforward and effective approach to fabricate porous silica capsules with well-defined asymmetric windows in the shell using raspberry-like templates has been developed. This process begins with the formation of a hierarchical template by chemically coupling a large polystyrene sphere to an ensemble of small, polystyrene latex spheres. The hierarchical template in conjunction with a hard templating method and spin-coating leads to silica capsules with well-defined, asymmetric pores (windows) in the outer shell. Proof-of-principle of this approach has been demonstrated using a 1500/110 nm hierarchical template. The silica capsules thus produced were characterized with scanning electron microscopy and STEM. The diameter of the capsules was ~1400 nm, and the outer opening of the windows was ~100 nm in size, consistent with the diameters of the core and satellite spheres considering the shrinkage due to the calcination. The inner opening was ~30 nm, which gives rise to an asymmetry factor, defined as the diameter of the outer window to the diameter of the inner window, of ~3. In another example, surface-bound capsules with an asymmetry factor of ~1 were made. Collectively, these windows can provide efficient pathways to connect the inside of the capsule to the outside and have potential for asymmetric diffusion and rectification.
已经开发出一种简单有效的方法，使用覆盆子状模板在壳中制造具有明确定义的不对称窗口的多孔硅胶囊。该过程首先通过化学偶联大聚苯乙烯球到小聚苯乙烯胶乳球的集合来形成分级模板。该分级模板与硬模板法和旋涂相结合，导致在外壳中具有明确定义的不对称孔（窗口）的二氧化硅胶囊。使用 1500/110nm 的分级模板证明了这种方法的原理。用扫描电子显微镜和 STEM 对如此生产的硅胶囊进行了表征。胶囊的直径约为 1400nm，窗口的外开口约为 100nm 大小，考虑到煅烧引起的收缩，与核和卫星球的直径一致。内开口约为 30nm，这导致不对称因子约为 3，定义为外窗口的直径与内窗口的直径之比。在另一个示例中，制造了具有约 1 的不对称因子的表面结合胶囊。总体而言，这些窗口可以提供将胶囊内部连接到外部的有效途径，并具有不对称扩散和整流的潜力。
