Theta solvent: Difference between revisions

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A '''theta solvent''' is the name for a condition (sometimes known as the [[Paul J. Flory |Flory]] condition) rather than an actual solvent. At the ''theta point'', in the words of Paul Flory: "''excluded volume interactions are neutralized''."
A '''theta solvent''' is the name for a condition (sometimes known as the [[Paul J. Flory |Flory]] condition) rather than an actual solvent. At the ''theta point'', in the words of Paul Flory: "''excluded volume interactions are neutralized''" (Ref. 1). Thus when polymer is added to a theta solvent it  will maintain the same  average end-to-end distance, unlike in a ''poor solvent'', where this distance is reduced, or in a ''good solvent'' where this length increases.
An excluded volume of zero connotes a [[second virial coefficient]] of zero. The theta state also corresponds to the highest upper critical temperature of a given polymer-solvent system.
An excluded volume of zero connotes a [[second virial coefficient]] of zero. The theta state also corresponds to the highest upper [[Critical points |critical temperature]] of a given polymer-solvent system.
==References==
==References==
#[http://nobelprize.org/nobel_prizes/chemistry/laureates/1974/flory-lecture.html Paul J. Flory Nobel Lecture]
#[http://nobelprize.org/nobel_prizes/chemistry/laureates/1974/flory-lecture.html Paul J. Flory Nobel Lecture]
[[category: polymers]]
[[category: polymers]]

Revision as of 17:38, 5 August 2008

A theta solvent is the name for a condition (sometimes known as the Flory condition) rather than an actual solvent. At the theta point, in the words of Paul Flory: "excluded volume interactions are neutralized" (Ref. 1). Thus when polymer is added to a theta solvent it will maintain the same average end-to-end distance, unlike in a poor solvent, where this distance is reduced, or in a good solvent where this length increases. An excluded volume of zero connotes a second virial coefficient of zero. The theta state also corresponds to the highest upper critical temperature of a given polymer-solvent system.

References

  1. Paul J. Flory Nobel Lecture