Neutron reflectivity study of adsorbed diblock copolymers |
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| Authors: | G S Smith C Toprakcioglu S M Baker J B Field L Dai G Hadziioannou W Hamilton S Wages |
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| Institution: | (1) Los Alamos National Laboratory, LANSCE, Los Alamos, NM, USA;(2) Physics Department, University of Patras, Patras, Greece;(3) Cavendish Laboratory, Cambridge, UK;(4) Department of Polymer Chemistry, University of Groningen, Groningen, The Netherlands;(5) Present address: Dept. of Chemistry, Harvey Mudd College, Claremont, CA, USA;(6) Present address: Solid State Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA |
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| Abstract: | Summary In this paper, we summarize our cumulative work on neutron reflectivity studies of polystyrene-poly(vinyl-2-pyridine) (PS-PVP)
and polystyrene-polyethylene oxide (PS-PEO) adsorbed at a quartz-solvent interface. Deuterated toluene was chosen as the solvent
since it is a good solvent for PS and a poor one for either of the other two blocks. In this case, the polystyrene dangles
into the solvent while the other block acts as an anchor. The neutron reflectivity studies reveal that the form of the polymer
density profile normal to the substrate may be varied from an extended ?brush? to a condensed ?mushroom? conformation by manipulating
the ratio of the molecular weights of the two blocks. In addition, we present new data on the PS-PEO system in a poor solvent,
deuterated cyclohexane, under conditions of shear flow in Poiseuille geometry. We find that when the PS-PEO diblock is absorbed
from cyclohexane and is allowed to relax, the PS chain takes on a ?mushroom? conformation. However, when the shear is applied,
the layer shear thickens due to the PS chains extending to nearly twice their original lengths.
Paper presented at the I International Conference on Scaling Concepts and Complex Fluids, Copanello, Italy, July 4–8, 1994. |
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| Keywords: | Neutron scattering techniques (including small-angle scattering) |
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