Fabrication of Core-Shell Polymer Nanospheres in the Nanopores of Anodic Aluminum Oxide Templates Using Polymer Blend Solutions

Spherical core–shell structures have been widely investigated in recent years, and they can be used for various applications, such as drug delivery, biological labeling, and batteries. Although many methods have been developed to prepare core–shell structures, it is still a great challenge to fabricate core–shell structures in the nanoscale with well-controlled morphologies and sizes. In this work, we present a simple method to fabricate core–shell polymer nanospheres consisting of polystyrene (PS) cores and poly(methyl methacrylate) (PMMA) shells. The nanostructures are prepared by a solution-based template wetting method. After the nanopores of anodic aluminum oxide (AAO) templates are wetted sequentially by PS/PMMA blend solutions and water, the core–shell nanostructures can be formed. The formation process is related to the Rayleigh-instability-type transformation. Selective removal techniques are also used to confirm the morphologies of the core–shell nanostructures.