Induced Electrostatic Interactions

The combination of electrostatic interaction (induced dipole—dipole interaction) with an increase in entropy resulting from the discharge of bound water is fundamental to PVP s abiUty to complex with a variety of large anions. 

The dynamic yield stress (extrapolated to zero shear rates, Figure 8.15) becomes greater with stronger field, indicating the increase of attractive forces between the polarized particles with applied electric field. This phenomenon is attributed to columnar or fibrillar structure formed by the particles as a response to electrostatic interactions induced by electric field. The stronger the field, the larger shear rate is needed to destroy the structure. 

Consider the interaction of a neutral, dipolar molecule A with a neutral, S-state atom B. There are no electrostatic interactions because all the miiltipole moments of the atom are zero. However, the electric field of A distorts the charge distribution of B and induces miiltipole moments in B. The leading induction tenn is the interaction between the pennanent dipole moment of A and the dipole moment induced in B. The latter can be expressed in tenns of the polarizability of B, see equation (Al.S.g). and the dipole-mduced-dipole interaction is given by... 

Our discussion of elecfronic effects has concentrated so far on permanent features of the cliarge distribution. Electrostatic interactions also arise from changes in the charge distribution of a molecule or atom caused by an external field, a process called polarisation. The primary effect of the external electric field (which in our case will be caused by neighbouring molecules) is to induce a dipole in the molecule. The magnitude of the induced dipole moment ginj is proportional to the electric field E, with the constant of proportionahty being the polarisability a ... 

The electrostatic interaction energy between the solute (represented by the charge distribution Q) and the polarizable medium represented by the induced charge distribution QP° e) becomes ... 

Hertel, C., Terzi, E., Hauser, N., Jakob-Rotne, R., Seelig, J., and Kemp, J. A. (1997). Inhibition of the electrostatic interaction between beta-amyloid peptide and membranes prevents beta-amyloid-induced toxicity. Proc. Natl. Acad. Sd. USA 94, 9412-9416. 

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