Expanded/extended coil conformation

When counterions are removed away from the doped polyaniline chain, the static repulsive interaction of the positive charges on the polymer backbone tends to extend this polymer chain from a more coil-like to a more expanded conformation. We think that solvents such as m-cresol probably work in this way. We note that these solvents are all phenols. The network of hydrogen bonds formed between phenol groups seems to provide an effective proton exchange medium through which the counterions can be removed from the polymer chain. 

As mentioned above, the structure of a polymer depends on the nature of the solvent. In good solvent excluded volume interactions lead to expanded conformations and under bad solvent conditions the polymer forms a dense coil. In a number of simulations the influence of hydrodynamic interactions on the transition from an extended to a collapsed state has been studied, when the solvent quality is abruptly changed. Both, molecular dynamics simulations with an explicit solvent [122] as well as MFC simulations [108,123,124] yield significantly different dynamics in... 

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