Block copolymer-based nanocomposites with exotic self-assembled structures induced by a magnetic field

Abstract

Structural control of polymer nanocomposites is important for their applications in organic semiconductors, lithographic nanopatterning, separation membranes, and nanofabrication templates. However, manufacturing nanocomposite materials with novel structures in a highly efficient yet precise manner remains a great challenge. To create nanocomposite structures, we combined self-assembly processing of block copolymer (BCP)-metal complex nanocomposites with an applied magnetic field. Here, we describe in detail the mechanism of magnetic alignment of block copolymers doped with metal complexes; specifically, we investigated the effect of the applied magnetic field on the phase behavior of the assembled block copolymer-metal complex nanocomposites with various molecular weights and with different molecular structures. We show that our combination of self-assembly processing and application of a magnetic field yielded lamellar structures of alternating multilayers with different layer thicknesses. This self-assembled structure is not included in phase diagrams of BCPs. The influence of the block copolymers’ molecular structures on the nanocomposites’ phase transformation behavior is also discussed. Our results provide a route to manufacturing nanocomposite materials in a highly efficient yet precise manner, which could lead to improvement in the material properties of nanocomposites.