Nonsolvent volume fraction, critical

When >0.5, becomes negative (attractive) this, combined with the van der Waals attraction at this separation distance, produces a deep minimum causing flocculation. In most cases, there is a correlation between the critical flocculation point and the 0-condition of the medium. A good correlation is found in many cases between the critical flocculation temperature (CFT) and the 0-temperature of the polymer in solution (with both block and graft copolymers the 0-temperature of the stabilising chains A should be considered) [2]. A good correlation was also found between the critical volume fraction (CFV) of a nonsolvent for the polymer chains and their 0-point under these conditions. In some cases, however, such correlation may break down, and this is particularly the case for polymers that adsorb by multipoint attachment. This situation has been described by Napper [2], who referred to it as enhanced steric stabilisation. 

For example, the emulsion will flocculate at a temperature (referred to as the critical flocculation temperature CFT) that is equal to the 0-temperature of the stabilising chain. The emulsion may flocculate at a critical volume fraction (CFV) of a nonsolvent, which is equal to the volume of nonsolvent that brings it to a... 

The cloud-point titration method (Section 6.6.5) can also be applied to copolymers whose monomeric units are chemically not very different. In this method, solutions of various concentrations are titrated with nonsolvent to the first cloud point. By extrapolation to 100% polymer, a critical volume fraction 3 of the nonsolvent is obtained, which normally depends linearly on the copolymer composition. 

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