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.