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Shear-Orientation of Nanocylinders in Thin FilmsIRG 2: D.E. Angelescu, J.H. Waller, D.H. Adamson, P. Deshpande, S.Y. Chou, R.A. Register, P.M. Chaikin, G. Arya, and A.Z. Panagiotopoulos Atomic force microscope (AFM) image of a shear-oriented diblock copolymer supported on a silicon wafer; the structure is shown schematically at the upper right; the hard (pink) cylinders appear bright in the AFM image. The cylinders all point in the direction of shear. Though only a small portion of the film can be seen in an AFM image, inspection of different regions shows that orientation persists over a large (1 cm x 1 cm) region. Self-assembly - utilizing the chemical properties of materials
to form ordered arrays - is one way to generate nanoscale structures. For example, small
domains of regularly arrayed cylinders are formed from a class of specially designed block
copolymers. However, the spontaneous nature of self-assembly leads to misalignment of
individual domains and, since overall orientational order is absent, the structures are of
limited use. Yet, we found that shearing a 30-nm-thick layer of a block copolymer induces
the cylinders to align along the shearing direction over large areas. These oriented films
are currently being used as masks for the fabrication of polarizers for UV light. Computer
simulations reveal that the orientation proceeds by the fragmentation and reassembly of
misoriented cylinders.
Related publication [DMR-0213706]:
D.E. Angelescu, J.H. Waller, D.H. Adamson, P. Deshpande, S.Y. Chou, R.A. Register, and P.M. Chaikin, Adv. Mater., 16, 1736 (2004). G. Arya and A.Z. Panagiotopoulos, Phys. Rev. E, 70, 031501 (2004).
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