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I know the flory temperature is the unique temperature at which the attractions and repulsions of a polymer in a solution cancel each other.

but what does this mean in practice? does it mean that this is the temperature at which the polymer and the solution mix best? and if you move away from this temperature it mixes less well?

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I'm going to use Theta-Solvent and Theta-temperature since that is what Wikipedia uses, and Wikipedia usually has the preferred names.

In order to get a polymer to the Theta-Condition two factors must be considered.

(1) Solvent

A Theta-Solvent is a poor solvent for a polymer is one such that the interactions between the polymer segments and the solvent are minimized. This results in polymer segment interactions to be maximized.

A good solvent for a polymer is one such that the interactions between the polymer segments and the solvent are maximized. This results in polymer segment interactions being minimized.

(2) Temperature

The Theta-temperature is the temperature for the particular theta-solvent which minimizes interactions between the polymer segments and the solvent.

Point

The combination of using a theta-solvent and being at the theta-temperature satisfies the theta-condition.

This makes experimental determination of important quantities such as the root mean square end-to-end distance or the radius of gyration much simpler.

Note

This assumes that polymer will self-coil into its lowest energy configuration. For polymers with same unit repeating this is not unlikely.

For proteins in biological systems this self-arrangement is unlikely. Proteins do not have a "repeating unit." Therefore biological systems have a mechanism to fold a protein in a certain way.

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At theta temperature, there are no interactions between the polymeric chains and the solvent. This means that the polymer doesn't mix well with solvent (The solvent is qualified as a poor solvent of the polymer). So, every polymer chain behaves as an ideal chain. The importance of the theta temperature and the theta solvent is to measure the characteristics of the polymer chain, such as the bond length and the bonds angle by cancelling the effect of the surrounding molecules of the solvent.

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