LONG-RANGE DENSITY FLUCTUATIONS IN A SYMMETRIC DIBLOCK COPOLYMER

: We present an experimental piece of evidence of the excess small-angle-scattering in a nearly symmetric diblock copolymer. This phenomenon is observed only in the two-phase coexistence region of the ordered and disordered phases near the order-disorder transition temperature, using the ultra-small-angle x-ray scattering method. This excess scattering is found to be caused by the difference of the density between the ordered and disordered phases in the coexistence region.