Hysteresis behavior in shear rate dependence of first normal stress difference of diblock copolymers in ordered state near order-disorder transition

Characteristic behaviors of viscoelastic properties in the quiescent ordered states were observed in shear rate dependence of first normal stress difference of diblock copolymers. An exceptional behavior was observed for DP and SP solutions just above order-disorder transition (ODT) concentration, which showed that there was no apparent change in the shear rate dependence of the first normal stress difference. Time slice measurements of SANS after the cessation of flow revealed that anisotropic scattering peak reflecting the perpendicular alignment still remains more than the half of initial value after 3 hours. Results showed that the parallel alignment becomes minor near the order-disorder transition (ODT) and/or high shear rate.