Phenyl group associations

The properties of the polycarbonate of bisphenol A are directly related to the structure of the polymer. The molecular stiffness associated with this polycarbonate arises from the presence of the rigid phenyl groups on the molecular chain or backbone of the polymer and the additional presence of two methyl side groups. The transparency of the material arises from the amorphous (noncrystalline) nature of the polymer. A significant crystalline structure is not observed in the polycarbonate of bisphenol A because intermolecular attractions between phenyl groups of neighboring polymer chains in the melt lead to a lack of flexibility of the chains that deters the development of a crystalline structure. 

Sometimes special attractions allow polymers to mix. This is true for the mixture of PS and PPO where the interaction between the phenyl groups allow the miscibility of the two polymers. For many combinations, such preferential associations are not present. 

Fig. 19 Current-voltage characteristics for ITO/donor/Cgo/BCP/Al based OPVs, donor = CuPC or PtTPBP. Images to the right show the structures of the donors and their HOMO and LUMO orbitals in blue and red, respectively. Steric interactions with the PtTPBP phenyl groups prevent close association of the donor and Cgo...

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