Synchrotron SAXS study of the microphase separation transition in diblock copolymers

The microphase separation transition (MST) in a nearly symmetric diblock copolymer is studied using time-resolved synchrotron SAXS. The transitions from the lamellar microphase to the isotropic melt and vice versa appear in the form of pronounced singularities in height and width of the main scattering maximum as a function of the temperature. The plot of the reciprocal scattering minimum S -1 (q * ) vs the reciprocal absolute temperature T -1 can be fitted to the corresponding theoretical function in the Hartree approximation although the present degree of polymerization N is much lower than the usually given limit of N>10 4