Tunable Thin Film Periodicities by Controlling the Orientation of Cylindrical Domains in Side Chain Liquid Crystalline Block Copolymers

Figure 4

SAXS patterns of PS-b-P8FMA sheared in the isotropic phase at 200°C at rates of 5 s^–1 and following thermal annealing at 150°C in the smectic phase for 3 h. The SAXS measurements were performed at room temperature by irradiating the X-ray beam along (a) vorticity (), (b) velocity (v), and (c) velocity gradient (∇v) directions. The observed patterns in indicate that the preferential orientation of BCP cylindrical domains is along the velocity direction and the smectic layers consisted of perfluoroalkyl side chains are arranged vertical to the BCP domains in the velocity direction. And the 1-D integration profile of 2-D SAXS pattern along the radius to the circle center by irradiating the X-ray beam along (d) vorticity (), (e) velocity (v), and (f) velocity gradient (∇v) directions. The smectic layer orientation is suggested by the absence of the smectic layer reflection in SAXS pattern irradiating X-ray beam from (b) the neutral velocity gradient direction. The scattering peaks attributed to hexagonally packed cylinderical BCP domain and LC side chain ordering are marked with red and navy triangle markers, respectively.

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