Anisotropic suppression of phase separation in polymer solutions by oscillatory shear

We consider the effects of subjecting a polymer solution to a simultaneous oscillatory shear flow and temperature jump into the two-phase region of the phase diagram. We predict that if the oscillatory shear stresses are significant enough then the flow suppresses phase separation in the flow direction, leading to the possibility of creating strongly aligned structures. We construct a quantitative dynamic phase diagram in the amplitude-frequency plane showing the conditions for the growth or decay of concentration fluctuations. Further, we discuss the time dependence of periodic structure factors in the flow-vorticity and flow-gradient planes. It is also shown that significantly enhanced scattering occurs at large scattering vectors regardless of whether the unbounded growth of fluctuations at smaller scattering vectors is suppressed.