upper critical solution temperature

Recommended acronym: UCST

Critical temperature above which a mixture is miscible.
Notes:
  1. Above the UCST and below the LCST, if it exists, a single phase exists for all compositions.
  2. The UCST depends upon the pressure and molar-mass distributions of the constituent polymer(s).
  3. For a mixture containing or consisting of polymeric components, these may be different polymers or species of different molar mass of the same polymer.
Source:
PAC, 2004, 76, 1985 (Definition of terms related to polymer blends, composites, and multiphase polymeric materials (IUPAC Recommendations 2004)) on page 1999