Patterning of Polyelectrolytes into Periodic Arrays using Block Copolymer Templates

Meirav Oded, The Institute of Chemistry and the Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel
Stephen T. Kelly, Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
Mary K. Gilles, Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
Axel H. E. Müller, Institute of Organic Chemistry, University of Mainz, Mainz 55099, Germany
Roy Shenhar, The Institute of Chemistry and the Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel

Nanoscale-patterned films are of great interest due to their applicability in a wide spectrum of disciplines, such as opto-electronics, medicine, biotechnology and energy. A successful patterning technique usually involves the existence of a chemical contrast on the surface. In that sense, a contrast based on electrostatic interactions can serve as a selective mechanism to distinguish between domains on a substrate. The Layer-by-Layer (LbL) assembly, which relies on electrostatic interactions between oppositely charged polyelectrolytes, can be used to create multi-layer arrays with controllable composition. This technique was applied to a variety of polyelectrolytes such as proteins, DNA, nanoparticles, clay, and on various substrate materials as well as on curved surfaces. Therefore, harnessing the LbL technique for site-specific depositions possesses a great potential for the creation of nano-structured films.

Here, we present a non-lithographic approach for the creation of periodic nano-patterns on large areas. Our approach relies on microphase-separated films of block copolymers, in which one domain type is chemically modified to render it charged. We characterized the kinetics of the deposition process of the first layer of poly(sodium 4-styrene sulfonate) (PSS) on two types of block copolymer patterns (hexagonally arranged dots and periodic stripes) and revealed new insights on the nature of nano-confined deposition.

This research serves as a cornerstone for the preparation of multi-layered nano-structures, and opens a new dimension in LbL construction of nanomaterials.