Critical length and time scales during the initial stages of nucleation in polymer blends

The initial stages of nucleation during liquid-liquid phase separation in polymer mixtures were studied by time-resolved small angle neutron scattering. The time required for nucleation vanishes exponentially as the stability limit (spinodal) is approached. The critical nucleus size decreases monotonically with increasing quench depth and remains finite at the spinodal. Our data differ qualitatively from theoretical predictions. (C) 2002 American Institute of Physics.