The enthalpic role in exfoliation

In the previous discussion, a great deal of time has been spent on approaches to surface modification of the clay nanoparticles in order to render the particles to be more compatible with the polymer of interest. This approach mainly concentrates on the enthalpic portion of the Gibb s free energy of intercalation-exfoliation. In order to realize the maximum benefit from a nanocomposite, the exfoliated state is the ultimate goal, since this will present the maximum interfacial interaction between the nanoparticle and the polymer. In reality, a completely exfoliated system probably does not exist, but a Boltzmann distribution of energy states is more likely which invokes some of the entropic terms. In the following 

The most common view of exfoliation is that if the surface modification of the nanoparticle matches the characteristics of the polymer, then exfoliation should occur. This, however, is too simple a view. A more correct approach is to look at the pairwise interactions between the components of the system. 

An example of this discussed earlier is the comparison of polyethylene oxide (PEO) and PVP. The PEO forms intercalated systems almost 

Neither will the situation where all pairwise interactions are equal give full exfoliation, since the likelihood of having unintercalated clay, intercalates, and exfoliates will be roughly the same, ignoring entropic contributions. Without a driving force for exfoliation, this situation would yield little exfoliation. 

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