Templated fabrication of fiber-basket polymersomes via crystallization-driven block copolymer self-assembly

Immobilizing uniform nanostructures on a mesoscale substrate is a promising approach to prepare nanometer to micrometer sized materials with new functionalities. The hierarchical structures formed depend on both the nature of the substrate and the components deposited. In this paper, we describe the use of colloidal polystyrene microbeads as a sacrificial template to create a nanofibrous network coating consisting of elongated block copolymer micelles. This network has a secondary structure very different from that of conformal coatings obtained by other methods. In addition, the fibers of the network could be elongated by crystallization-driven self-assembly. The network was locked in place by cross-linking the micelles through in situ generation of small Pt nanoparticles. Subsequent removal of the sacrificial template gave an open vesicular structure. To demonstrate further transformation of the membrane, we showed that the cross-linked micelles could also be used to embed silver nanoparticles. The sacrificial template contained known amounts of Tb and Tm ions, allowing us to estimate via atomic mass spectrometry that 85% of the template surface was covered with micelle seeds. This approach to fabricating hierarchical coating structures expands the generality and scope of template-assisted synthesis to build advanced hierarchical materials with precise morphological control.