title: Structure and Dynamics of Asymmetric Poly(styrene-b-1,4-isoprene) Diblock Copolymer under 1D and 2D Nanoconfinement.
abstract: The impact of 1- and 2-dimensional (2D) confinement on the structure and dynamics of poly(styrene-b-1,4-isoprene) P(S-b-I) diblock copolymer is investigated by a combination of Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), Grazing-Incidence Small-Angle X-ray Scattering (GISAXS), and Broadband Dielectric Spectroscopy (BDS). 1D confinement is achieved by spin coating the P(S-b-I) to form nanometric thin films on silicon substrates, while in the 2D confinement, the copolymer is infiltrated into cylindrical anodized aluminum oxide (AAO) nanopores. After dissolving the AAO matrix having mean pore diameter of 150 nm, the SEM images of the exposed P(S-b-I) show straight nanorods. For the thin films, GISAXS and AFM reveal hexagonally packed cylinders of PS in a PI matrix. Three dielectrically active relaxation modes assigned to the two segmental modes of the styrene and isoprene blocks and the normal mode of the latter are studied selectively by BDS. The dynamic glass transition, related to the segmental modes of the styrene and isoprene blocks, is independent of the dimensionality and the finite sizes (down to 18 nm) of confinement, but the normal mode is influenced by both factors with 2D geometrical constraints exerting greater impact. This reflects the considerable difference in the length scales on which the two kinds of fluctuations take place.
authors: †Institute of Experimental Physics I, University of Leipzig, Linnéstraße 5, 04103 Leipzig, Germany.
authors: Wycliffe K
authors: WK
authors: Kipnusu
authors: †Institute of Experimental Physics I, University of Leipzig, Linnéstraße 5, 04103 Leipzig, Germany.|‡Department of Physics, Mansoura University, Mansoura 35516, Egypt.
authors: Mahdy M
authors: MM
authors: Elmahdy
authors: †Institute of Experimental Physics I, University of Leipzig, Linnéstraße 5, 04103 Leipzig, Germany.
authors: Emmanuel U
authors: EU
authors: Mapesa
authors: ¶Physik-Department, Physik weicher Materie, Technische Universität München, James-Franck-Straße 1, 85748 Garching, Germany.
authors: Jianqi
authors: J
authors: Zhang
authors: §Institute for Experimental Physics II, University of Leipzig, Linnéstraße 5, 04103 Leipzig, Germany.
authors: Winfried
authors: W
authors: Böhlmann
authors: ∥Cornell High Energy Synchrotron Source (CHESS), Wilson Laboratory, Cornell University, Ithaca, New York 14853, United States.
authors: Detlef-M
authors: DM
authors: Smilgies
authors: ¶Physik-Department, Physik weicher Materie, Technische Universität München, James-Franck-Straße 1, 85748 Garching, Germany.
authors: Christine M
authors: CM
authors: Papadakis
authors: †Institute of Experimental Physics I, University of Leipzig, Linnéstraße 5, 04103 Leipzig, Germany.
authors: Friedrich
authors: F
authors: Kremer
mesh_terms: D002070:Butadienes / Q000737:chemistry*; D005898:Glass; D045782:Hemiterpenes / Q000737:chemistry*; D008422:Materials Testing; D056004:Molecular Dynamics Simulation; D049329:Nanostructures / Q000737:chemistry*; D036103:Nanotechnology; D010420:Pentanes / Q000737:chemistry*; D011137:Polystyrenes / Q000737:chemistry*; D053838:Scattering, Small Angle; D014961:X-Ray Diffraction
chemical_list: D002070:Butadienes; D045782:Hemiterpenes; D010420:Pentanes; D011137:Polystyrenes; C005059:isoprene
keywords: confinement; diblock copolymers; dynamics; glass transition; structure