title: Three-dimensional multilayered nanostructures with controlled orientation of microdomains from cross-linkable block copolymers.
abstract: Three-dimensional (3D) nanostructures were obtained by the directed formation of multilayer block copolymer (BCP) thin films. The initial step in this strategy involves the assembly and cross-linking of cylinder-forming polystyrene-b-poly(methyl methacrylate) (PS-b-PMMA) BCP, in which 1.5 mol % of reactive azido (-N(3)) groups were randomly incorporated along the styrene backbone. Significantly, assembly of thin films of lamellar-forming BCPs on top of the underlying cross-linked cylindrical layer exhibited perpendicular orientations of microdomains between lamellae and cylinder layers. From the theoretical calculation of free energy in the multilayers, it was found that the nematic interactions between polymer chains at the interface play a critical role in the perpendicular orientation of lamellae on the cross-linked cylinder layers. Removal of the PMMA domains then affords nonsymmetrical nanostructures which illustrate the promise of this strategy for the design of well-defined 3D nanotemplates. It was also demonstrated that this structure can be effectively used to enhance the light extraction efficiency of GaN light-emitting diodes. Furthermore, we anticipate that such 3D nanotemplates can be applied to various areas, including advanced BCP nanolithography and responsive surface coating.
authors: Department of Chemical and Biological Engineering, Korea University, Seoul 136-701, Republic of Korea.
authors: Hyunjung
authors: H
authors: Jung
authors: Dongjune
authors: D
authors: Hwang
authors: Eunhye
authors: E
authors: Kim
authors: Byung-Jae
authors: BJ
authors: Kim
authors: Won Bo
authors: WB
authors: Lee
authors: Justin E
authors: JE
authors: Poelma
authors: Jihyun
authors: J
authors: Kim
authors: Craig J
authors: CJ
authors: Hawker
authors: June
authors: J
authors: Huh
authors: Du Yeol
authors: du Y
authors: Ryu
authors: Joona
authors: J
authors: Bang
mesh_terms: D008027:Light; D008689:Methacrylates / Q000737:chemistry*; D049329:Nanostructures / Q000737:chemistry*; D036103:Nanotechnology / Q000379:methods*; D011137:Polystyrenes / Q000737:chemistry*; D013499:Surface Properties; D013816:Thermodynamics
chemical_list: D008689:Methacrylates; D011137:Polystyrenes; C522509:polystyrene-block-poly(methyl methacrylate)