Polymer blends unit mixture volume

Flory-Huggins Theory. The simplest quantitative model for AGmx that includes the most essential elements needed for polymer blends is the Flory-Huggins theory, originally developed for polymer solutions (3,4). It assumes the only contribution to the entropy of mixing is combinatorial in origin and is given by equation 3, for a unit volume of a mixture of polymers A. and B. Here, pt and... 

For the assumptions made in the derivation of the above equation, see Appendix 2. A. Equation 2.3 can also be used when both components 1 and 2 are polymers in the case of a polymer blend. The equation can be written in terms of the change in entropy per unit volume of the mixture as... 

We saw in Section 2.5 that the thermodynamic approach used for polymer-solvent mixtures can be used for polymer blends (mixtures of two polymers). For simplicity, let us consider the case of two polymers that have the same molar volume. In the lattice model, this would correspond to chains with the same number of segments. The entropy per unit volume of the mixture given in Equation 2.4 can be written as... 

Getachew et al. recently published an interesting new BHJ composition. The authors reported that PSC blends perform better when a fullerene-deriv-ative (PCgoBM acceptor) is blended with a 1 1 mixture of two thiophene-based polymers, D1 and D2, having the same conjugated backbone but different types and volume fraction of alkoxy side chains on the phenylene-ethynylene unit (Fig. 3.6). 

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