Term: upper critical solution temperature (UCST)
https://doi.org/10.1351/goldbook.UT07280

Definition:
critical temperature above which a mixture is miscible.

Notes:
0) Above the UCST and below the LCST, if it exists, a single phase exists for all compositions.
1) The UCST depends upon the pressure and molar-mass distributions of the @C01281@ polymer(s).
2) For a mixture containing or consisting of @M03667@ components, these may be different polymers or species of different molar mass of the same polymer.

Related Terms:
1) constituent (http://doi.org/10.1351/goldbook.C01281).
2) polymeric (http://doi.org/10.1351/goldbook.M03667).
3) critical temperature (http://doi.org/10.1351/goldbook.C01402).

Source: PAC, 2004, 76, 1985. 'Definition of terms related to polymer blends, composites, and multiphase polymeric materials (IUPAC Recommendations 2004)' on page 1999 (https://doi.org/10.1351/pac200476111985)

Citation: 'upper critical solution temperature (UCST)' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. https://doi.org/10.1351/goldbook.UT07280

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