Small-angle neutron scattering studies of the phase behavior and mesophases of homopolymers, block copolymers and complex mixtures

Small-angle scattering of X-rays and neutrons are particularly powerful techniques for studying complex materials such as polymers, micellar solutions and lyotropic mesophases of amphiphilic molecules. In the present paper, we review some of the recent progress on polymer complex fluids made using small-angle neutron scattering. These studies include examination of the phase behavior of binary polymers where fluctuations due to the free volume significantly renormalize the critical behavior. Block copolymers phase-separate on the microscopic level given by the length scale of the polymer coils and form a variety of mesoscopic ordered phases. Blends of homopolymers and diblock copolymers show new physical phenomena where different critical behavior meets in a Lifshitz point. Block copolymers in selected solutions self-assemble into micellar structures which provide the basis for ordered structures.