Title: θ state
Long Title: IUPAC Gold Book - θ state
DOI: 10.1351/goldbook.Q06240
Status: current

Definition
The state of a polymer solution for which the second virial coefficient is zero.

Notes
1) In some respects, a polymer solution in the θ state resembles an ideal solution and the θ state may be referred to as a pseudo-ideal state. However, a solution in the θ state must not be identified with an ideal solution.
2) The solvent involved is often referred to as 'θ solvent'.
3) It is assumed that the molar mass of the polymer is high.

Related Term
- virial coefficient: https://goldbook.iupac.org//terms/view/V06625

Source
- Purple Book, 1st ed., p. 57 (http://old.iupac.org/publications/books/author/metanomski.html)

Other Outputs
- html: https://goldbook.iupac.org/terms/view/Q06240/html
- json: https://goldbook.iupac.org/terms/view/Q06240/json
- xml: https://goldbook.iupac.org/terms/view/Q06240/xml

Citation: Citation: 'θ state' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. 10.1351/goldbook.Q06240
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Accessed: 2026-06-14T02:30:34+00:00