nucleation of phase separation

in polymer chemistry
Initiation of phase domain formation through the presence of heterogeneities.
Note:
In a metastable region of a phase diagram, phase separation is initiated only by nucleation.
Source:
PAC, 2004, 76, 1985 (Definition of terms related to polymer blends, composites, and multiphase polymeric materials (IUPAC Recommendations 2004)) on page 1997