Copolymers Self-Assemble Multiple Times To Form Complex Structures

A self-assembly technique allows chemists to build polymeric structures on the micrometer length scale. The new method is hierarchical, first assembling nanoscale structures that then organize into larger ones. The resulting structures could ultimately be used for molecular electronics and drug delivery applications. Ian Manners of the University of Bristol, in England; Mitchell A. Winnik of the University of Toronto; and coworkers developed the method by building on a previously reported one called living crystallization-driven self-assembly (CDSA), which produces individual micelles. In CDSA, block copolymers in which one of the blocks forms a crystalline lattice self-assemble into cylindrical micelles. In the new method, these micelles help build structures that can self-assemble into larger “supermicelles” (Science 2015, DOI: 10.1126/science.1261816). The researchers use the individual micelles to seed the growth of larger block comicelles, which are micelles with multiple types of segments. The block comicelles have alternating hydrophobic and polar segments. The nanometer-scale block comicelles self-assemble into micrometer-scale structures, such as three-dimensional superlattices, according to the arrangement of the segments and the polarity of the solvent.