Surface-Induced Ordering in Graft Copolymer Thin Films
| Autor: | Steven Schwarz, Lantao Guo, William D. Dozier, Shouren Ge, Miriam Rafailovich, Ralph H. Colby, Jonathan Sokolov, Dennis G. Peiffer |
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| Rok vydání: | 1999 |
| Předmět: |
Materials science
Silicon chemistry.chemical_element Surfaces and Interfaces Condensed Matter Physics Micelle Styrene Secondary ion mass spectrometry Crystallography chemistry.chemical_compound chemistry Polymer chemistry Electrochemistry Copolymer General Materials Science Lamellar structure Thin film Spectroscopy Phase diagram |
| Zdroj: | Langmuir. 15:2911-2915 |
| ISSN: | 1520-5827 0743-7463 |
| DOI: | 10.1021/la980556o |
| Popis: | The surface-induced ordering of deuterated poly(ethylacrylate)-polystyrene (dPEA-PS) graft copolymers with different average number x of graft chains per copolymer chain (dPEA-g-xPS, x = 1, 3, 5) was investigated using neutron reflection, secondary ion mass spectrometry, and atomic force microscopy. The ordering starts only at the vacuum surface and decays through the bulk of the film to the silicon surface. The dPEA-g-3PS thin films (f, fraction of styrene monomers = 0.28) appear to have dPEA-PS lamellar structures and a nearly pure dPEA layer next to the vacuum surface. The dPEA-g-5PS thin films (f = 0.48) are found to be cylindrical except for the top layer, adjacent to the vacuum surface, which is lamellar. On comparison with diblock copolymers, graft copolymers show a phase diagram shift and smaller micelle spacing. The authors find that long-range order in graft copolymers only occurs within {approximately}15 lamellar spacings of the vacuum surface. Linear viscoelasticity of bulk samples reveals that none of the shear-history and low-frequency terminal response complications observed for diblock copolymers are observed for graft copolymers, owing to their lack of long-range order. |
| Databáze: | OpenAIRE |
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