In-situ small-angle neutron scattering from a block copolymer solution under shear
- Polytechnic Univ., Brooklyn, NY (United States). Dept. of Chemical Engineering
- National Inst. of Standards and Technology, Gaithersburg, MD (United States)
- National Inst. of Standards and Technology, Boulder, CO (United States)
Small-angle neutron scattering profiles from a concentrated (65 wt%) polystyrene-polyisoprene block copolymer solution in dioctyl phthalate under shear were obtained both above and below the quiescent order--disorder transition (ODT). The ordered solution has a lamellar structure under quiescent conditions. The shear-induced structure was inferred from scattering measurements in two planes: the v-vx[del]v plane and the [del]v-vx[del]v plane (v is the fluid velocity direction and [del]v is the velocity gradient direction). Below the quiescent ODT, oscillatory shear produces lamellae that are aligned along the shearing surface, while steady shear results in a reorientation of the lamellae normals from the v-vx[del]v plane to the [del]v-vx[del]v plane. Above the quiescent ODT, steady shear induces order above a critical shear rate. The resulting scattering anisotropy obtained at different temperatures obeys a universal scaling law, and the critical shear rate increases exponentially with temperature.
- OSTI ID:
- 7037032
- Journal Information:
- Macromolecules; (United States), Vol. 27:9; ISSN 0024-9297
- Country of Publication:
- United States
- Language:
- English
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