Block Copolymer Micelle Nanotubes by the Solvent-Annealing-Induced Nanowetting in Anodic Aluminum Oxide Templates

Abstract

Block copolymer micelles are generally formed by the self-assembly of amphiphilic copolymer molecules in aqueous medium. Although different types of block copolymer micelles have been studied, the self-assembly behavior of block copolymer micelles in confined geometries have been rarely studied. In this work, the fabrication of polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP) micelle nanotubes in the cylindrical nanopores of anodic aluminum oxide templates using a solvent-annealing-assisted wetting method is presented. The PS-b-P4VP chains wet the pore walls in the form of micelles when the sample is annealed in the vapor of toluene, a good solvent for PS and a nonsolvent for P4VP. The formation of the PS-b-P4VP micelle nanotubes instead of nanorods implies that the micelles wet the nanopores in the complete wetting regime. This study not only contributes to a deeper understanding of the self-assembly behavior of block polymer micelles in confined geometries, but also provides more possible variations and design freedoms in the application of block copolymer micelles.