Flow mechanisms in the face-centred cubic micellar gel of a diblock copolymer

• Published in: Colloid and polymer science Vol. 279; no. 10; pp. 1029 - 1033
• Main Authors: Castelletto, V., Hamley, I. W., Yang, Z.
• Format: Journal Article
• Language: English
• Published: Berlin Springer 01.10.2001; Springer Nature B.V
• Subjects: Alignment; Applied sciences; Close packed lattices; Copolymers; Exact sciences and technology; Hexagonal cells; Organic polymers; Orientation; Physicochemistry of polymers; Properties and characterization; SAXS; Shear; Solution and gel properties; Walls; Oscillating flow; Shear flow; Steady flow; Diblock copolymer; Physical gel; Ether copolymer; Propylene oxide copolymer; Aqueous solution; Ethylene oxide copolymer; Experimental study; Micellar solution; Mechanism
• ISSN: 0303-402X; 1435-1536
• DOI: 10.1007/s003960100538

The mechanisms of flow of a face-centred cubic micellar phase were investigated using small-angle X-ray scattering (SAXS) for samples under either steady or oscillatory shear in two different geometries: Couette cell and planar shear sandwich. The system studied was a gel formed by a poly(oxyethylene)-poly(oxypropylene) diblock copolymer in water. SAXS indicated that under steady shear in a Couette cell, flow occurs via sliding of hexagonal close-packed (hcp) layers with a close-packed [110] direction along the shear direction. Under oscillatory shear in the planar shear sandwich, coexistence between this orientation and one in which the hcp layers are rotated by 30° (and flow is in a [211] direction) was observed; however, when subject to oscillatory shear in the Couette cell, flow only occurred along a [110] direction. This observation of flow in a non-close-packed direction may be due to alignment induced by the walls of the shear sandwich.[PUBLICATION ABSTRACT]