Entropy- and Energy-Driven Nematic Ordering

The same physical picture can be applied to dispersions of spherical colloidal particles. At lower concentrations of the colloidal particles, the system is in an isotropic fluid phase. On increasing the concentration, the colloidal particles contact each other and the space, or free volume where they can freely move, becomes less. The free volume, however, can increase when the colloidal particles form a crystalline 

When the interaction between rods is only a short-range attractive interaction, the Pj of Eq. (2.6) can be given by  

Equation (2.5) can also lead to the McMillan model [32] for a smectic A phase of polymer-rod blends [33] (Section 2.3.5). When the system is spatially non-uniform 

These fundamentals will be applied to construct the free energy for flexible and rigid rod polymer blends in the next section. 

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